Classic Winnebagos & Vintage RVs

Sent: 5/23/2004

I have an '87 Winnebago Chieftain 22' with a 454 engine. I was getting 10 mpg. It started dropping down to 5 mpg. I have given it a complete tune up, changed the fuel filter and adjusted the carburetor. I'm still running between 5 and 7.9 mpg. Is this normal for this rig? My driving is mixed highway and city with a normal load, water and two people. Tires are also inflated properly and can find no fuel leaks.
Would appreciate any advice on this.

Jim

Sent: 5/23/2004

If thats a carburetored engine, you might check if the vacuum advance is still working. When they get a leak in the vacuum bladder the thing will drive just the same, but the mileage will suffer. Also check that your handbrake isnt dragging. If it has a mechanical centrifugal advance inside the distributor, make sure that mechanism isnt stuck and failing to operature - mileage and power would suffer. It would have an EGR valve, and unless you have replaced it in the last 10,000 miles or 2 or 3 years, I would suspect it of being stuck slightly open. If the engine has TBI, then try getting an extra computer, and swap it out to see if its a failure of one of the computers modes. I have an 87 chevy van with the 350, and I carry extras of all the engine electronics with me on long trips, as spares. I got most of them from ebay, and have swapped them with what was on the motor to make sure they work. If it has an O2 sensor, how long ago was that replaced?
My 1972 winny with the 413 gives me 8 mpg or slightly less.

Sent: 7/27/2004

I did a 680 mile round trip from San Diego to Paso Robles this weekend. Went to Eberle winery for dads 60th B-day. Went up the 5 over the grape vine and across the 46 to get there. Then down the 101 home. Lots of steep grades. On the 5 is the grapevine and the 101 has a couple also. She did 60 to 65 mph on all grades and 60 mph on the flats. I push the hills hard just to see what she will do. Never got above 215 degrees on the climbs and pulled down 8.12 MPG.

This engine is in tip top shape with an excellent tune. I don't baby the gas at any point. I push hard on the hills. I come off the line hard to get to speed when entering the highways. I always floor it when passing on the highway. This was the first trip without towing a trailer and I didn't do any better in MPG. Oh well.....

Sent: 8/1/2004

WW ....... how about a restricted air filter ??... IN a non dusty enviorment - TRY removing the filter completely THEN take a mpg read. I think that you will be surprised.

Sent: 8/4/2004

Un-ohh!  Bad move, Discoverer.  Even a small particle of grit or dirt can do immense damage to the engine.  Besides, a replacement air filter only costs about $5.00 -- cheap enough to just change out even if not really needed.

John

Sent: 8/14/2004

Ive run without air filters for a long ways, 2000 miles once, when I forgot about the filter being out. All on highways. Worst problem was when I had to tweezer an insect out of the venturi inlet. Carburetors get dirty even with the air filter on anyway, just more slowly.

Sent: 6/26/2007

Yea! mileage up! 7.13 over a 200 mile haul, avg speed 55-60 to the pond and back. Ok it's not Excalibur's astronomical numbers but hey it beats 5.4.  I know my tires are about 10lb low all the way around.... Both places I stopped at  the guages didn't go over 80lb nor did they have the attachment that can do the double back tires. Yes I now have a good guage on board as of today.
And no I wasn't hauling a van, water,  or running the genny. As TJ said, Gone is just a heavy old RV....  Still have yet to stop at a scale because I'm either in a rush to get someplace or in a rush to get home to get her cleaned up...oiy.

Tina

Sent: 6/27/2007

Yay Tina!!!

7.13 mpg is GREAT mileage...I think Excalibur is a fluke...lol!  On that note, do you have a vacumm guage on the dashboard?  I pay close attention to the vacumm guage when I'm driving, adjusting my driving style and speed to maximize the amount of vacumm the guage is reading.

The higher the guage reads, the more efficiently the engine is running, and thus the better gas mileage you will get.  It seems to work!

Sent: 6/27/2007

No vac guage on the dash.... I have yet to fully check out the vac system... we disconnected a bunch tubes off the old carburator housing when we dropped in a K and N filter thing... Stoppered up a few and the others my mechanic didn't think were significant... but who knows... 
thanks!
Tina

Sent: 8/19/2007

Never gotten her weighed yet..... but we don't haul full water or tanks etc. Everything is empty 98% of the time. We take on maybe 15gal of water because we usually stop on the side of the PA turnpike for dinner etc....  hmmm. lets see basic poundage calculation... for bodies... 535lb .  All dinner ware is plastic. pots and pans can't be more than 15lb.

So... we filled up at the Heartsgrove BP coming in, that mileage was 5.9 running full genny with 15 gallons of water, all refuse tanks empty. We ran to Sandusky with maybe 5 gallons fresh water, and 30+gallons black and grey water since we didn't pump out.  We didn't run the genny to Sandusky but we did do some serious hills taking a back road by some Ski place.... We tanked up on the way back somewhere on the PA pike last stop before Breezewood.  We ran the genny from the OH PA border home.  Avg mph 55-60 given it was pouring horses, cows, pigs, puppies etc... and calculated 6.6mpg!!!  yipee!! haven't tanked again but probably will this week if I see gas prices going up by even a cent. 

I did notice a bit more energy on the gas. I want to redo the snorkel intake next chance I get... Going to see if I can fit something solid vs the crushed flex thats there even if I have to do a go around so its not in the 1+ inch on the side of the engine by the doghouse.

Question though. Can I put in a Y so some gets in through the rain diverter in front but some gets sucked off the side bottom? Thinkin' to mount a side scoop or something to catch air  up by the engine to the right etc....... any suggestions?

Tina

Sent: 9/5/2007

I've watched this thread with earnest since it was started.  My mileage has been in the 9-11 range since I've owned it.  It drops to the 6-7 range if driving over the mountain passes.  The previous owner did many mods to the 454...headers, dual 3" exhaust with Flowmaster 40 mufflers, and a K&N Air Filter.  Still running the stock intake snorkel.  I always drive in the 60-65mph range, as I find that the most comfortable speed for this rig.

I just had the oil changed and found the K&N to be almost plugged!  Just plain filthy.  I went ahead and put a stock paper element in its place as I am using it this weekend, and on the drive home it seemed to have a little more spunk.  I'll watch the mileage and the vacuum guage this weekend...it's about a 500 mile round trip...maybe we'll see some improvement.  I'll clean the K&N later when I have the time.  I cannot believe how dirty it was after only this spring/summer's use, around 1500 miles!

John - Jazzin112
'84 Winnebago ElanDan 31RT 454 "Ol Snort"

Sent: 9/7/2007

I took off the KN assembly I had bought  mid 2006 and we put back on the original snorkel and all its vacuum tubes (some of which were open to air connecting to inerior engine parts...) with a clean paper filter.  I need to redo the flex tube that runs from a ram intake rain blocker thing as it is crushed and twisted etc. There is little to no clearance between the doghouse and the engine for it so looking into ways to go around/under with a solid or multiple solid tubes.

Filling up before we headed out last weekend mileage was 6.2 running genny  on the PA turnpike then through Breezewood over the appalachians and back home.  Our mileage out was 7.1 over the same roads running full genny.

I put on a new set of plug wires ("best" set not cheap), pulled a couple of plugs.

Our rig has 2" dual exhaust original with original mufflers. Temp runs in the normal range. Had the transmission flushed 3K ago along with the radiator. Oil changed in the spring. Gone just flipped 70K.

Next project is snorkel feeder ram air system.... Need to see what clearance we actually have and what I can fit in.... 

tina

Sent: 9/20/2007

Well, highway speed certainly does effect the gas mileage we are getting in Excalibur!  On the way from Wisconsin to Texas, I averaged about 65 mph, since we were in a hurry...and when I calculated the mileage, we were only getting around 8 mpg!  So, from Salado, TX to Plantersville, TX, about 150 miles, we drove at exactly 55 mph...and mileage was right back up to around 11 mpg.  Lesson learned:  Keep it at 55!

Kev

Sent: 10/8/2007

Just a Gone to the Dawgs update... Took Gone out to Trap Pond for our family fall get together. 100 miles each way and had to run the genny for AC on the way there as temps were nasty especially with 4 dogs panting in unison.....

Gassed up and weighed up on the way back. With a probably 3/4 load of fuel (55 gal or so) all dogs and probably 1/3 food load, empty black and grey tanks... Gone weighed in at 13,185lb. Rear axle was about 8500 and front 4800 or so. She took on 38 gal of fuel for 298 miles of driving. I kept to the 50-55 limit as I have driven her for all of those miles (included in were our trip to "Aqualand on labor day weekend). And..... 7.8 MPG!!! yipee! Figure 8 average due to genny.

No haven't had time to even look at the snorkel ram air intake issue yet. This weekend was all about relaxing, food and friends.

Tina Pat and da pups

Sent: 5/12/2008

i have a 76 brave 22 footer with a 440 in it and i sometimes tow a two place atv trailer and i have never gotten less than 8 mpg. the motor is in fine tune so i think that is the big part. i never loose any power on hills, so far anyway. i do have headers and full duals, i think that makes a big difference. had to wrap the headers with header tape as they were heating the starter up. everything seems to work good though. i could use a good set of plug wires as these have seen better days. any suggestions where in ontario to get plug wires for a 76 440 dodge? in the good old days growing up on the prairies i would just go down to the napa but i ask for parts for a 440 and they look at me as if i am speaking a foreign language. sad.

Sent: 6/9/2008

We got about 10.2 mpg coming up to Kentucky from Georgia up 75...towing the loaded Astro van, without the genny running...Maybe the mountains lowered the mileage a bit...lol!  There were some STEEP long grades on the way up here!  So steep even the 454 was laboring, pedal all the way down just to maintain 55 mph, and then coasting on the downhills...which were too curvy to really coast at full speed with without hitting the brakes and slowing down...which killed our momentum at the base of the next mountain...very pretty trip though!  Even though I kept hearing a SQEEEEELLLL SQEEEKK CHIRRRRRP that had me CONVINCED something was wrong with the rig!!!  It was just the cicadas!!!

Kev

Sent: 6/10/2008

I've noticed, and I might be just imaging it, that not only driving habits, weather conditions, geographic location will effect the MPG'S ...but a large factor could be the type (BRAND) of petro used. At times for me, it has differed 1 to 2 mpg. And 1 to 2 mpg's with our gas classic guzzlers, is a big....big factor.

Here around Louisville, KY during the spring and summer months the comapanies go to a re-formulated gas (KY law...to make some the Greenies happy)
No matter which vehicle I put the re-formulated crap in, fuel mileage goes down, the driving habbits, weather,  etc. stays the same. Now living just a crossed the boarder in Indiana we are not subject to the Kentucky re-formul;ated gas law, but unfortunatly, some stations may carry it from time to time due to the fact that the fuel comes from the same distributors, and I hate it when I get it in my tank....even the lawn mower uses more fuel to mow the same area.

On a trip once,  from NY to Florida, (in 24 hours) I notied that the no name fuels such as Sprint, Econo-gas Big-Foot etc. as opposed to Shell, Sunnoco, Mobile, EXON,  got 1 to 2 mpg better, the drive was all on I - 95 which is a pretty level interstate for most of the way. Except though parts of VA. One driver and the weather conditions did not change.

I was wondering if I was crazy for noticing this, or maybe it was an illusion. Has anyone else noticed a difference in fuel milage by Brand? If you did or do, post it here.

Timmy

Sent: 6/13/2008

Timmy,
I believe you are right. My 02 SS Camaro convertible was finally ready for the dyno last week.

It has always had premium fuel, and only premium fuel from the the "biggest" name fuel supplier around.

When they tried it on the dyno, it made no power above 22 degrees of timing. After hours of tearing things apart, they sampled the fuel quality.

The specific gravity was 798 ( Damn near water ). We pumped out the very full fuel tank and put in 5 gallons of ethanol enriched fuel from the local discount el cheapo gas station, which measured 645 specific gravity.
Instantly, the camaro wanted 28-29 degrees of initial timing and we saw an additional 29 HP and 41 foot/pounds at the wheels.

Jay

Sent: 6/13/2008

Dont forget that fuel for the 'pumps' is refined/blended in different ways, depending on the season of the year and the climate where it is sold (higher volatility in North Dakota in Feb. compared with Texas in August among other factors), and depending on the type of crude oil the refinery is intaking. That is to say, you get different gasoline, -a different mix of hydrocarbons- if the oil comes from different oil fields. (Arabian crude is about the best, Venezuelan crude seems to be the worst) Fuel is also blended differently depending on the requirements of the state it will be sold in, and sometimes different areas within a state.
And of course including ethanol affects the amount of energy a gallon has in it; the more percentage of ethanol, the less BTU's of energy a gallon will have.
But I suspect the variables due to a decades old carburetor and the equally old distributor centrifugal & vacuum advances has as much to do with the miles you get to a gallon.

Sent: 6/22/2008

Ok, new airlifts and new shocks all around... and... the result is... 9.8MPG! yipee! Last tank was 6.2.... go figure... 

Tina

We have a 37 ft. Elanden with the 454 and have never gotten more than 6 mpg, 5 mpg is the standard, this is just a fact I have had to accept. After numerous trips, short, long, flat, mid summer, winter, regardless the mpg never varies much above 5 mpg. I once discovered a fuel leak at the fuel pump and just knew my mileage was going to double, no dice, apparently it only leaked while ideling, I guess at speed the fuel demand from the engine drew the fuel up the line so very little actually was lost. I have never weighed the rig, but we never carry fresh water, or full holding tanks, tire pressure is always monitored, clean air filter, oil changed regularly etc. It just is what it is 5 mpg, thankfully gas is not 4 bucks a gallon anymore.
Rick aka 89Elanden

We have not had our 1984 31' Elandan for that long so don't know what the MPG is yet. I noticed a MPG gauge in the upper left on the dash I wonder if this is just a glorified vacumm guage ??? This is one of the largest vehicals I've driven " aside from a Sub " and it has VERY little spunk and sometimes gives me a back fire.

We average about 7.2 at this point if I'm driving as my foot isn't quite as heavy as  Pat's. We never haul with full water tanks, we may put 10-15 gallons in so that we can pull over on the PA turnpike and cook dinner and use the facilities etc but thats it.

I put a naked KN filter assembly on her in fall of 07 but we got 3.2 driving her in cold snowy wet air... so we reinstalled the old air filter assembly. I still have to get a KN for it so for now its just paper filter. I also need to redo the snorkle from the assembly as the one there leads to a ram air intake near the radiator but the hose is about beat to death.... The carburator leaked like a sieve when we bought her so  new edelbrock has helped but its still running a bit too rich as she will run on sometimes after cutting the engine off and will very occasionally backfire. I added racing level silicone plug wires and made sure all are in thier clips as we had 2 melt on us, talk about no pep! running on 6 cyl vs 8.... Dropped in new plugs as well.

I'd never driven anything as big either other than a big Ford dually tractor. I just take it easy I know I am a land boat.... She weighs in at 13,883 lb with 4 dogs, 1 human and basic supplies.

As I've said many times.. price of RV $$, price of customizing $$, price to fill her up $$ - having your own potty on the road and the joy of being able to escape reality when you need to ... Priceless!!!

Tina

Hey Rick!

I would imagine that because your rig is almost 40 feet long its a LOT heavier than ours.  That said, I would still imagine your should be able to squeeze 8 mpg out of her with some modifications to the carb and intake, and of course the exhaust.  Perhaps ram air induction and the like as well. 

The one thing I've noticed over the last couple of years and I say this as gospel truth is that sticking to 55mph (coasting down a hill excluded of course) will maximize your gas mileage.

Also, getting a vacumm guage and then modifying your driving habits so that you are drawing as high a vacumm as possible in various conditions will also maximize your fuel economy.

These two elements are to me the most critical and crucial means of getting better gas mileage, and they are definately under your control...and they cost nothing to do.

Our gas mileage varies widely depending on terrain, wind direction, and even the road surface.  Provided I stick to the 55mph rule and keep an eye on my vacumm guage (driving habits now at this point), I get anywhere from 11mpg maximum, to as little as 6mpg.  I try to stick to highway driving for the long haul, stay in the slow lane at 55, and plan my trips so that I don't end up in rush hour traffic near any major city.  We've pulled over many times into rest areas if we were approaching a major city and it was near rush hours.

And wind direction does play a major factor.  On the same road going the same speed, I've gotten 11mpg with the wind at my back, and less than 9 into a headwind.

All of the above of course is dependent on keeping your engine in maximum tune with good plugs and wires, cap and rotor, a clean air filter, good current flow from the alternator and coil, a clean and well tuned carb, an exhaust that flows efficiently enough, timing set properly, clean oil to keep the lifters and everything else running smoothly, brakes adjusted properly so they don't drag, driveline greased to keep friction to a minimum, tires inflated to near maximum pressure, etc.

There are a lot of factors involved and even doing everything "right" your mileage will still vary...but at least you have control over most of the factors.  Dave Denison is quite correct though when he states that fuel quality and mixes play a major factor in your fuel efficiency and you can't really control this factor...but you can certainly maximize everything else.

Kev

When I drove my Midas from Dalton, Ga to Harrison Bay St. Park last Oct., I averaged 10 mpg.  Granted it was only 40 miles, but it still gave me an idea what to expect.  1oleman(Ed)

Ok, finally got a preliminary MPG on the 84, 31' Elandan.... 6.19 and that is with basically a new fuel system. Oye... Truth is I don't know when it was last tuned up so maybe I should just bite the bullet and have that done. It has had Air Bags in the past and has the stuff for them like air lines and a set of front and rear pressure gages but a look at the springs shows me just a bunch of corrosion there. Is it worth it to clean that out and have new bags put in??? I mean most of the stuff is there maybe it is salvageable.

The air ride suspension if functioning would improve your ride comfort, but probably not your mpg. Unlike the air in your tires, which definately affects your mpg, the suspension,  affects the bumps, rolls and sways of the cabin and the occupants within. If you can get it operable, you might notice a big difference in the ride. I was amazed at the ride improvement after I installed new shocks and steering stabilizer.
Rick   

My good friend Mick just bought a very nice 25 foot Fleetwood, 1977, with a P-30 chassis, and his front air springs are nothing but hole-infused sponges (he's replacing them soon)...and his ride sucks compared to ours.  Air springs make a HUGE difference in the ride.

I'm not sure how MUCH it will translate into fuel economy, but as far as when I used to race mountain bikes, good suspension made a HUGE difference with rider efficiency, and I'm not just talking about comfort.  You could go faster and smoother with a lesser effort, the better your suspension was.  This was due to your tires and therefore forward momentum always maintaining contact with the surface you were riding on.

I would imagine this would translate to our rigs...if your suspension is maximized for road contact as well as comfort, I would imagine that this would translate to better fuel economy.  Your engine would not have to work as hard, just like the ideal in bike racing.

Kev

The air bags are obvious in their improvement in ride, but you won't see any difference in your gas mileage.  Well, maybe 1/10th of a mile better per 50 miles.  Nevertheless, they are worth it for the safety and comfort of improved stabiliy and handling.

I replaced my swiss cheesed airlifts in the front springs last April (2008), and in sept 08 installed new Bilstien shocks all the way around, and installed a new steering shock... I didn't see an improvement in gas mileage at all but I am a happier camper driving her which is worth it!

Tina

I finally got a good idea of what the gas millage is and it is just over 6.5pmg... Oh well. That is with the genny going and towing a Chevy cavalier and up and down on half and half back roads with some slight " Texas " hills. I was hoping for more as we just had her tuned up " back fires are all gone and she has much more spunk " but it is better than the 4.5 I originally thought she was getting.

As much as I hated to do it I had to put in a new carb...I got it from Summit Racing...professional rebuild by Holley...almost 500 buck...ouch!  It was the only Quadrajet they had with the right CFM (750) and a hot air choke.  I couldn;'t have me old one rebuilt, although I saved it for parts, because the body was actually broken near the filter intake...some PO hade peiced it together with JB Weld and it came apart when I went to change the filter.  Good thing it didn't come apart while driving, eh?

Unfortunately the hot air choke on the new carb was different from the one on the old...it hooks up to the manifold differently...so I had to reuse the old choke and there are minor clearance issues.  I didn't know it was sticking on the way from NY to NC and I only got 6 MPG!

I troubleshot it in NC but ran out of time to fix the issue completely, but by manually freeing up the choke once it warmed up my gas mileage went back up to almost 10 mpg...pretty flat roads. 

While I'm here in Florida I'll fix the problem once and for all...one of the little dohickies on the choke sticks out and barely contacts the carb body...I can free it by barely touching it with a screwdriver.  I've marked where it strikes, so out it comes when I have time and I'll dremel a little bit for clearance off the dohickie.

Kev

Gone got a new carb (edelbrock 4bbl quadra) right after we bought her as her old carb had warped and gas was dripping out of gasket below carb all over the engine... not good. I think it is still running a bit rich but my mechanic looked at it, timing is spot on, have tiny vac leaks in emissions valves.... drive 55-60 easy on the hills etc... and we still only average 7.2 or so. No towing. empty water tanks. Rig is 13,800lb.

I'm contemplating the AirTabs like Frank put on Patricia.  $280 investment as we will need 80 or so.  Frank gets 2-3mpg better since putting them on.. They do look a bit silly and Pat is balking...

I'm hoping to replace all the vacuum tubing this winter with silicone. and at some point we are driving Gone up to Brad's shop in NJ to have new exhaust manifold gaskets (and probably manifolds) put on.....

8-10mpg would be heaven!

Tina

Remember Frank has a 350 not a 454  you have to feed all the horses   104 more CID uses more fuel  Frank

 Sounds like some of those vacumm lines went to something important.

I had my Quadrajet rebuilt last December, but I haven't put it on, yet.  I have an Edelbrock on it at present but I'm not impressed with it's power.  The carb works okay, but it just doesn't seem to put out the horsepower I need to go up simple grades.  I'm hoping putting the Quad back on will help.  It cost $188 to rebuild in Florida and they seem to have done an excellent job, but I'll only know for sure after I reinstall it.  I haven't driven the old Holiday Rambler enough to tell what the MPG is.  I really don't care since I never go very far in it.  180 miles is about as far away as I have gone.  At 6 miles per gallon that would be about 60 gallons round trip.  At $4.00 a gallon that comes to about $240.  Actually, maybe I do care!

Banks Power Torque tubes - check
Magna Flo - flow throughs - check
Full tune up - check (and next time that will include a new ignition coil  W% ) wires, plugs, rotor, cap.

10.2 mpg Freakin Rocks!!!!  :)clap :)clap :)clap :)clap

but warning.. do all the above and there is a ton under the pedal... so even though you can haul proverbial booty up hills... don't... 3.6pmg on first fill up pulling hills because I could... babying her up in "happy" rpm mode... 10.2.... in slow lane 45mph or so on flats 60ish...

wohoo!!! now to fix the radiator fan clutch... its always something!
Tina

Alright!  After the tune up...and remember, we already have Banks headers and mufflers on the muscle car sounding Nautilus...we got 9.1 mpg from Huntersville, NC, to Brunswick, GA's Flying J, where we are right now.  That is fully loaded, towing the Jeep, loaded pretty heavy and weighing in at just over 5K lbs. 

We are still running the quadrajet, since it ain't broke don't fix it.  10w-30 oil.  New wires, plugs, cap, rotor, etc. 

Granted, this probably won't be indicative of our average MPG, since coming out of NC into SC and then GA is coming OUT of the appalacians, and a lot of flats and downhills, and there was very little wind.

But 9.1 is the best we've gotten so far, except when I first bought her and drove her, empty with no extra weight but the fuel, from MA to NY, and got close to 13 mpg.

Oh, and we drive 55-60 mph on average.  We don't push her hard on hills, but try to maintain at least 55.  This trip she had no problem at all keeping that speed on any of the grades that we went up.

Sweet!

Kev

My first mileage check on my new to me 28' 454 SW. New wires, K and N and a light foot.
20 percent highway, the rest in town, lots of idling for AC recharge and stuff, AC on most of the time.
250 miles, 29 gallons for 8.5mpg.
This is what my first RV used to get around town. It was a 24' chassis mount w/283 Chevy, 2 bbl and 4 speed. No power anything.
Flatland road trips should get around 10, in fact that's what the old Chevy would avg on the road with ONE trip at 13mpg!
Works for me!

Are you using a whole K&N setup, or just a K&N filter in the stock air cleaner housing?  I've heard Chevy's don't like it when you change out the air cleaner housing to aftermarket, especially in the cold weather.

Kev

Quote from: ClydesdaleKevin on August 02, 2012, 08:11 AM
Are you using a whole K&N setup, or just a K&N filter in the stock air cleaner housing?  I've heard Chevy's don't like it when you change out the air cleaner housing to aftermarket, especially in the cold weather.

Kev

Just the filter.

Pulled a 5000 lb car/trailer combo 250 miles. Major long grades through the mountains, full throttle about 175 of those miles and got 6 mpg.
If someone would have driven the car the combined avg mpg would be 26 so I really got 13! Howzat for fuzzy math!!  :angel:

Had a partially clogged fuel filter for the first half so I really had to gas it to make headway. Sputter, stumble, pop....

Hi, I am new to this forum.  I have an 22' 86 Winnebago Chieftain on a Chevy P30 chassis with a 454.  I've owned it since 09.  My average mpg is 6.49 over 2200 miles. 

I've averaged all of the mpg's stated in this thread and it is 7.968 for 30 entries. 

So I have a lot of work to do on my winne to gain 1.5 mpg.  Thanks for all of the helpful suggestions.

Thank you!  I never thought to work-up an average.

Quote from: DonD on September 26, 2012, 06:44 PM
Pulled a 5000 lb car/trailer combo 250 miles. Major long grades through the mountains, full throttle about 175 of those miles and got 6 mpg.
If someone would have driven the car the combined avg mpg would be 26 so I really got 13! Howzat for fuzzy math!!  :angel:

Had a partially clogged fuel filter for the first half so I really had to gas it to make headway. Sputter, stumble, pop....

Just returned from the same trip this ti me pulling a dolly with the same car on it. 400lb dolly netted 9 mpg plus. Bye bye trailer. EDIT : I calc'd this mpg by the guage and did drive more miles in varied terrain. Must be honest, the final mpg was 8.

Gotta do something about our current gas mileage.  Went downhill in a hurry, and that was before the Edelbrock, which gets the same poor economy as the malfunctioning Quadrajet but at least has decent power on hills.

Down to an average of 6 mpg.

Not good!

I really need to add a vacuum gauge to the Nautilus to verify good vacuum, although it seems good when you pull a line while its running.

Maybe the EGR valve went bad?

Gonna replace it before we leave Louisiana to see if it makes an impact...cheap enough part.

Distributor moves with my vacuum pump, so the vacuum advance is working.

Might try a new air cleaner setup depending on how my next post's answers pan out.  Edelbrocks work best with open airflow from everything I've read.

Nothing else I can think of to explain the recent drop in fuel economy!  Thought it was LACK of fuel flow to the RQJ since it was rebuilt and tuned to a lower fuel flow from the disconnected in tank pump.

But when I replaced the fuel pump mileage didn't go up at all, power dropped due to the tuning of the carb, and we were running too rich and almost flooding.

The Edelbrock brought the power back so I can climb hills at 55 now, but the fuel economy is still right around 6 mpg.

Some element on the equation changed...just gotta figure out what it is!

Kev

One of the best solutions for gas milage on any carberated 454. Hot rod the distributor.

Pep Boys sells a kit for around 90 dollars.  kit includes high output coil, adjustable vaccum advance ,new weights and springs etc.  This kit changes the timing curve witch increases power and fuel economy.  Install kit and advance timing as far as you can without starter kick back.  Big blocks usually love about 28 degrees lead.

If you dont have a timing light to do this, loosen distributo,r turn counter clockwise untill you hear spark knock. turn back one eighth of a inch and tighten distributor. Test drive if there is bad preignition turn ditributor one eighth inch at a time and retest.  If only minor preignition it can be eliminated by adjusted vaccum advance with allen wrench included in kit.

Another important thing to check is that the vaacum line to distributor advance is from a ported connection on carburetor.  which means you only get vaccum at 1/4 and up throttle. 

This kit also lowers exhaust temperature by up to 6 to 7 hundred degrees which we all know is a huge problem with these rigs no more cracked manifolds or donut burn outs way cheaper than banks exhaust.

One more big thing get rid of the air pump. they never worked on these vehicles, only raise exhaust temperature more and modules are no longer available for them.   As far as enviromentalists go, be happy your rig will burn cleaner and more efficient than it ever did.  At 28 degrees of lead timing the fuel is burning in the cylinder where it should and not in the exhaust manifold where its doing nothing but destroying your ride and the enviroment not to mention your wallet at the price of gas. 

One more thing excuse my typing can make a motor run like a bat out of hell but cant type to save my own butt  Hope This Helps Gary

Just don't want to advance so much you end up burning out valves.  Thanks for the input Gary!  I'll keep that in mind as the modifications continue!

Kev

If theres no preignition or in other words ping your safe.Been doing this for years to our tow vehicles. My Brother and i tow to the salt flats every year Pulling a 45 foot race car trailer loaded to the max. Believe me you will feel the difference.Run amsoil lubricants and use only this performance change never got less than 300000 miles out of a motor. If your into land speed or hot rods check out brothers shop on the web Delaware Chassis works or there land speed track in Ohio  ECTA  East Coast Timing Association . Hey saw that you changed to a edelbrock carb did you modify the stock air filter to fit and duct the the intake back to the grill. Don't run a open filter like they usually try to sell you with these carbs.The design of the dog house and the frame rails will pull every ounce of air away from the motor and destroy fuel economy and performance .actually built duct work from grill to right and left bank on my motorhome secondary fan only comes on now when outside temp goes above 95 degrees and all the vaccum lines plug wires etc. love me for it.  If you don't have any luck with with your Egr plate let me me.I could find some time to build you one at the race car shop.   Gary

Thanks Gary.  Found a block off plate at Summit Racing.  Experimentally I'm going to try the open filter, but I'm keeping the stock one just in case...we'll see how it runs on the way out to San Antonio.  My coach has basement storage, so the engine sits lower in the body of the coach compared to most older motorhomes, so its not boxed in...should be plenty of airflow.  My running temps stay right around 185 degrees unless I'm pulling really steep hills, then it never goes over 200.  If its running fine, I'll leave it alone.  If I'm noticing a lack of air getting to the carb as you suggest, I'll temporarily modify the stock air cleaner and hook it back up to the snorkel hose.  I don't trust the way the spacer sits on the stock filter...makes a crappy seal.  Ultimately Spectre makes a double snorkeled air cleaner housing that would work beautifully, but we'll see how the open filter works first.  The Spectre air cleaners are expensive!

Kev

Kev first chance to get back to you your motorhome is the same as mine except 4 feet longer when i was having trouble with manifolds over heating i taped card board all around motor and used inspection camera drove down rd.when motor home went over 35 miles per hour all air pulled away from motor.The wheel wells on these are a piss poor design and there isnt a firewall air goes through radiator then splits to the far right and left of motor right down the outside of the frame rails.I would have a metal spacer welded to your stock air cleaner also saw on your other posts that you still had charcoal spark arrester in air cleaner pry that piece of junk out of there, you will never get air with that junk.One last thing i know that this is  another big expense but edelbrocks don't work all that well unless there mated with with a edelbrock manifold completely different design from the q jet manifold.but then again Chevy's will run with just about anything.Read up on the distributor upgrade i told you about it completely changes the timing curve witch gives you power through the entire range.  One more dumb thing check your fuel it could be the whole problem there selling some real garbage out there next to water.  Have a good trip Gary

Hip hip horray!!!
After installing an Edelbrock 1411 carburetor with a spread bore adapter and using the stock air cleaner, I was getting about the same poor gas mileage as the messed up Rochester Quadrajet.

I drove from St. Mary's Georgia to Hammond, LA, and averaged 5.9 mpg...ye gads!!!  It was time for some extreme measures!

I took out EVERY unnecessary vacuum line, leaving only the ported vacuum line to the distributor advance, the big vacuum line to the PCV valve, and the full time vacuum line has only one connection to a steel line that goes under the engine, which I imaging has to do with the transmission...I left that one on there.

Pulled out every AIR hose except one from each pump, which I left attached to the manifold AIR boxes.
Pulled out the EGR valve and used a block of plate and gasket.
Removed the hose and gasket from the passenger side valve cover and installed an Edelbrock breather.
And finally, installed a 3 inch high by 14 inch Edelbrock open element air cleaner.

(http://i1114.photobucket.com/albums/k526/ClydesdaleKevin/Projects%202012/DSCF1962rs.jpg)


(http://i1114.photobucket.com/albums/k526/ClydesdaleKevin/Projects%202012/DSCF1964rs.jpg)


Once all these changes were made, I started the engine and let it fully come to temperature, and the idle was now 1000 rpm instead of 700!

I adjusted it down to 700, and then adjusted the idle mixture screws to the side of lean...easy to do on an Edelbrock, just turn them in slowly until the idle drops, then back them out 1/2 turn.  Both screw heads even ended up in the exact same position...gotta love Edelbrocks!

Then I had to increase the idle a bit, since it had dropped to about 650.

I revved the engine, and it droppped to a steady 700 rpm immediately , and for the first time since owning this RV, there was no fluctuation at all in the idle no matter how many times I revved it.

The real test was today's road test!

The first part of the trip was out of the campground in Hammond, Louisiana, and then I-12 West, then I-10 West, almost to the Texas border where we had to stop for gas, since we started out with just at a quarter tank.  We recorded the mileage, how many gallons used...and holy crap!!!

8.8 mpg!!!

Okay, maybe a fluke, or a miscalculation...we set the odometer trip meter to zero, and kept heading West.  When we pulled into a Flying J tonight, exit 789 just east of Houston, I filled up again, and recorded the gallons to fill it up.  Divided the miles by the gallons, and it was

8.5 mpg!

The first figure was an estimate, since we didn't know exactly how many gallons had been used out of the tank before all the vacuum line and air cleaner changes had been made.  The guage was reading 3/4, so we subtracted 15 gallons from what it took to fill up the RV and came up with that figure or 8.8.

The 8.5 is no crap dead reckoning!

HECK yeah!

And there is no lack of power now!  This thing runs better than it ever has before.  It wants to fly up the hills, but I keep her back to save gas.  Almost every single hill/bridge was taken at 50mpg without opening the secondaries!!!    Had I wanted to open up the secondaries, she immediately accelerates up the hills, but for the sake of good gas mileage, I kept the pedal light!

The only bridge where I had to open the secondaries to make the hill at 45mph...and by the time she reached the top she was doing 55...was the big high and long bridge coming out of Baton Rouge, LA.  That's one heck of an incline, so I had to open them up.

This mileage was achieved also in part to a very light foot on the pedal, keeping her at 55, patiently taking the steep hills at 50 so the secondaries wouldn't open, and accelerating slowly...no need to get there fast!  A couple of other times I had to open up the throttle and let the engine have her power, and both times it was because of some idiot on a cell phone coming up an on ramp and not paying attention to the big RV about to turn them into scrap metal.

Okay, so enough rambling.  A solid 8.5 mpg after all the mods I made, with great power up the hills, and smooth quiet performance on the flats.  I ain't gonna complain about that!

Kev

From that improvement, it won't be long at all until you've recouped the cost of the changes and then, feel your wallet staying heavier at the pumps!

:)   :)ThmbUp

Kool sounds like you earned it.Read your plugs one time if there lite gray a little more towards the dark side your not running too lean enjoy   Gary

Thanks Gary.  With Edelbrocks, those screws only effect idle mixture...lean it out and you won't burn as much fuel at stop lights and stop signs or in gridlock traffic.  Pretty much all they do.  If you want to go richer or leaner on an Edelbrock at speed, you have to replace metering rods and jets and springs...which I don't plan on doing at all with the mileage we are getting!


Kev

Mileage report updated:

Got an incredible 8.5 mpg all through Houston...and then it got hillier.  We were leaving sea level, and its all uphill from here!

Calculated the latest mileage at our latest fuel stop in San Antonio, TX.  Elevation gains from now on all the way to Arizona!  Long rolling hills...had to open the secondaries on a couple hills to maintain highway speed.

Still getting an average of:  7.37 mpg!!!

Can't complain about that, especially since I was keeping an average steady speed of 50-55mph unless I was coasting downhill as fast as she wanted to go!

And Gary, great idea about the inspection camera!  That got me to thinking...a webcam and a strong light positioned just right and aimed at well painted timing marks sure would make a one-man timing adjustment a lot easier!

Kev

I found out, through reading the book RV RX for Performance, that gas engines get the best fuel economy at around 38 mph (standard gearing)...go figure! 

Since at higher elevations my fuel economy dropped down to about 7 mpg, I decided to try it out, taking back roads and highways recently from Tombstone, AZ to Safford, AZ, and from Safford to Hot Wells Dunes, and sure enough, my MPG went from around 7mpg, to 10+ mpg!  I can definitely live with that!  I kept it to right around 40mph, coasting down the mountains, easy on the pedal, and avoided opening the secondaries whenever possible.  Sure made the trip more pleasant too...you can actually enjoy the scenery at 40!

There were lots of steep climbs, but rambling along at 40mph was pretty easy to do.  I'll let you all know how she does on the next leg of our journey...Hot Wells Dunes to Apache Junction, AZ, about 100 miles on Route 70 to Hwy 60 and some pretty steep inclines and declines.  I'll also be able to keep the speed down on these roads, so I'll update this report in a couple of weeks.

Kev

That book is available in the Club Store - It's loaded with all kinds of great information and it's written so even the least mechanically inclined individual (like me) can undertand it completely!  It also covers simple, cheap fixes for known, common problems with all the major brand chassis!

http://www.classicwinnebagos.com/forum/index.php?action=store;sa=view;id=184 (http://www.classicwinnebagos.com/forum/index.php?action=store;sa=view;id=184)

This is a very valuable yet highly overlooked publication which I recommend to everyone.  No matter how much you may know, you'll definitely learn more from this book!

This must be some book.  I looked it up on Amazon.com and found you can still get a new copy for $110.  But, Barnes and Noble wants closer to $300 for it.  I happened to find a hard back copy in like new condition for 75cents at BargainBooks.com.  However, it costs $4.00 shipping.  I can't wait for it to arrive.

Its a good read too.  The authors take the time to explain everything in a way that makes it a nice read...technical enough so you don't feel like they are talking to an idiot...but simple enough that anyone can understand what they are talking about.

I'd love to have a hard copy some day (to read outside on the porch, etc.) but the club store here has it for 8 bucks, so its hard to beat!

Worth every penny!

Kev

Just filled up. 50-50 city/hwy. I have recently removed the carbon filter thingy in the OEM air cleaner housing. hopefully helping  my KN get more air.

Did something right..8.9 mpg!

Awesome Don!  Our next voyage is from Apache Junction, AZ, up to Sedona, taking I-17.  I have been told the elevation gain is gradual along I-17, but I'm very curious what our gas mileage will be climbing on a highway where I have to try to maintain 55mph.  I'll let you all know in a few days once we reach Sedona!

Kev

I did a lot of the "fixes" that have been mentioned in this tread; including the ones that you wouldn't think would improve mpg.  Like, 4 new bilstein shocks and steering damper, replaced the front airbags and two in the rear, rebuilt the quadrajet, replaced all vacuum lines, changed the oil and tranny fluid.  Put 60 pounds of air in the tires.  Filled up the water tank, propane and a full tank of gas.  Drove from Meridian ID. to Silver City ID. a 132 mile round trip.  Never exceeding 60mph. No wind rolling hills. 

I got 8.3 mpg. Lucky I guess.

My last 5 fill ups avg is 8.1!   The last tank was up and down I-17 to SR 260 to Dead Horse Ranch State Park pulling my Tracker on a trailer, the mpg was 7.6.

Heading out Fri. for a 2 nighter. the route has some long climbs and I will be dragging the same set up, hope my avg doesn't dip... too much.

8/2/13    7 tank avg= 7.55. All trailer/dolly miles, lots of hills. In Sept we plan to do Grand Canyon w/o towed. Stay tuned.

8 tank avg...8.3.

Some of my earlier mileage figures were based on incorrect info. from a GPS that when compared to a new Garmin, was a bit off. Subtract about 10 percent  :-[ I thought the odo. was off...isn't after all.

With my new unit (matches map and odo. miles) my MPG is about like everyone elses....About 7. I did get 10 on a short run (90mi) with 2500lb 4x4 on 14ft car trailer on FLAT roads.
My last 4 tanks avg. is 7.3, excluding the 10 mpg run...that's too short really.

"Takes what it takes"!!

Poop. When was last tune-up done?

Averaging very low 7s lately, but the K5 Blazer is 900 lbs or more heavier than the old Jeep YJ, and the rear suspension shock mounts on the RV were broken.  Gonna fix the mounts before our next trip to Oklahoma in April, and I'll let you all know what it is then.  If its not much of an improvement, then it might be the intake I installed restricting air...might have to do a double snorkel intake.  Or headers.  Or both...lol! 

Kev

The last tune up WILL be done soon :) (None done since I've owned her)

EDIT: The number 8 plug boot was melted. I used 2 gal. more last trip than the same trip in October and this time I was towing about 1000lbs less wt. Now I know why it used more and didn't seem "quite right". I haven't found an OEM boot cover so off to Napa tomorrow for a new aftermarket one and a new neutral sw. The wire was not making contact, as I pulled the boot it came apart.

The in-laws last trip a couple weeks ago...averaged 6.75 mpg, staying at 55 mph's, towing a 2,800 car. We were happy, it's been as low as 5.75 in the past. How much more you really going to get with a stock 454, pulling 15k? If your getting 7 +, Thats great!! :)

Someone on this site a few weeks ago said "I just figure on 30 dollars an hour to operate the rig"....thats pretty right on.

Yup...50 cents per mile.

I always figure its a dollar a mile....as its not just gas  that gets ya down the road....

On our new (to us) 1989 Winne Warrior (454 carb) we had calculated an average mpg of 5.5 mpg in mixed highway (55-60 mph) and secondary/curvy/hilly roads over six tanks of gas. After reading some of the suggestions here, the easiest suggestion seemed to be to to adjust the parking brake. (This despite the fact that I had paid the shop to do this three months ago.) So I parked on a small hill and set the parking brake. Transmission in neutral and slowly let my foot off the brake. It didn't move. So I started loosening the adjustment which is right there on the p brake handle. I must have turned it twenty times before the p brake started to release. I continued to loosen it by two turns. Then I started turning it back tighter by about a half a turn at a time until the brake held the RV on the hill. Then I turned one more half turn.

Subsequently, on the trip just completed yesterday from Martinez CA up to Salt Point State Park and back, (about 250 miles) the mpg was 7.8 mpg. (mixed highway (55-60 mph) and secondary/curvy/hilly/very narrow roads) and an imaginary egg between my foot and the gas pedal.

There are a number of other things I want to look at re. mileage but this one small thing is going to save me $$$. Thanks everyone.

I finally got a road trip out of mine last weekend  :)clap .  About 200 miles and averaged 6.96 .  Fairly flat terrain here in Ks  W%   and pulling my boat around 3500 lbs.  Planning to lean out the primary side of my QJ, but won't get to that till this fall probably.  Will have a 520 mile round trip in a few weeks.

I just filled up after our Labor day trip and YEE HAW! 11 MPG while towing a trailer! That was filling up at the beginning of Rt. 29 in Virginia and going down to Syria and then back to NJ while towing a trailer with a 4'000 lb. Jeep on it. Trailer and Jeep about 6,000 lbs.. I couldn't believe it so I ran the route through he GPS to be sure the mileage was correct and it was. I still have the touch. :)clap :D ;)

I just installed a glass filter at the carb. That handy thing was the only way we could be certain that we were making any headway addressing our fuel delivery issues. We recently replaced the thermostat, and the engine doesn't seem to get hot at all, so I am not sure we are at risk of the vapor-lock issue I've read about on here. Should I take that filter off anyways?

I have a 413, not a 454, but it sounds like the consensus is that these glass cased filters are no good at the carb regardless of the vehicle.

I wouldn't mind that formula for 11 MPG! Heck, I am going to be excited to get past 6 with this rig.

I am not going to get really exited about the mileage since it was one trip. the tank before that was 7 MPG but I had two lengthy breakdowns with my trailer where I was idling for long periods so I cannot say anything yet about the mileage for sure. As far as the filter, a filter in that location is good, just not THAT filter. I had a major issue with one of those clogging up and did not look it at all. Turned out the plastic media in the filter melted due to the alcohol in the gas. Never again. A good name brand clear plastic one is good if you want to see what is in it or a metal one for ultimate safety. Be aware that the clear plastic ones never fill all the way up with gas due to the position of the inlet and outlet. It is not uncommon to look almost empty and be running just fine. A lot depends on the position it is in.

Looking back over my mileage logs for the past 2 yrs..... Banks headers, Edelbrock quad, magnaflow mufflers, KN filter inside stock snorkel, AIR removed but EGR etc still on. 7.4 is my overall average.  This past tank which was only topping off after 225 miles was a measly 6.4 but those miles were in chilly damp (mid/low 60F's rain) air which she doesn't like. Avg speeds 50-55 fairly flat runs no generator running, waste water tanks empty.  Also depends on who fills the tank, and slight angle Gone is parked at and if I'm patient enough to really top it off to the last drop.  I made a note last fill at where the pump read when the auto cut off happened, and then where it stopped after I allowed the fill pipe to settle and stopped and started the pump to allow it to completely top off.  The difference in mileage calculations was 0.7mpg....  so that additional 2+ gallons made a pretty big difference.  Calculations based on the odometer reading.   
    And yea at current $3+USD prices/gal... $30 per hour or so is dead on, more if you are billy goating hills and towing etc.  do have to add with the headers on etc.. having that extra power when you need it is nice though I know she drinks from the McDonalds milksshake large bore straw when I need those secondaries open.... :-)
Tina
   

Tina, The air you describe is actually the best air for making power. Cool damp air is dense and packed with moisture which creates lots of power. I think some of my gain was due to the fact that I had a vibration which I did not know what it was, Still don't, and I was really pussyfooting the gas. I did not need another breakdown on the way home. I am going to go over all of my figures all the way back for a couple trips, I gave the last mileage to my wife to write in at the last stop before this one and I am wondering if she got the figures wrong. I have to admit that does sound too good to be true. It will be easy enough to backtrack and check, just need time which is in short supply when I am working.

Mine is a stock 454 and my uncle swears that he was getting 7.5 mpg and 8 when he was pulling his 1/2 ton Chevy. The only mod done was a Gear Vendor. When I go down the road and turn on the Gear Vendor everything gets quiet and it feels like driving a car. So the cost of that unit compared to engine mods and balancing fuel and air mixtures. I'd go with the Gear Vendor.

Cold and damp is great for making power.. just drains the gas tank.  Worst mileage ever was 3.2mpg had put on a naked K&N assembly, figured more air the merrier.. drove in driving snow 32F... the K&N didn't have the hot air return for the carb.... probably had some icing going on.  Thus K&N inside original snorkel and Banks accommodates the exhaust back to carburetor.   

If you are going to be driving in weather that is below 40 degrees you have to have the hot air intake or you will have carb icing in damp weather. That is just like driving with the choke on.

just repaired the factory cold Air-Intake at my 454.

They had already installed a really big pipe from the front over the radiator to the Air Filter housing. It was only fallen off and had to suck behind the coolers.

Mileage: the former owner told me something of about 10mpg if I stay under 60. My first fill was around 10, the last one (with Horsetrailer through the hilly country) at around 7.5 mpg. (without the cold air)
I've still got some issues with filling up.


First, all the Fuel stations stop after $100 on my cards :P I could pay cash, but the cheapest fuel station is BJs (like Costcos) which are 10 cents cheaper and there is nobody to take green.  annoying...
Next, after the first auto shut off, when I wait just a little bit I can get in another 10 gal ? till the next shutoff occurs.
So I don't know really when my tank is full or if I got a hyper sensitive fuel pump...
And my Fuel gauge is no help either, the first 10-15 gal it doesn't move a bit.

I purchased a K&N filter to fit into original canister.  Replaced ram air intake hose too as its a tight fit and old one was shredded due to friction point routed into doghouse....   I love the K&N, brush it off, spray it with cleaner, hose it off, shake out, let it dry, spray with the oil... done.  Have them in all of my vehicles.

As for filling up... yes patience is a virtue.... the fill tube is long as the tank sits in the middle of the chassis so it will stop and start if the flow is too fast as it backs up.  Sometimes if I can get the fill handle in at a 45 angle it will stay on for most of fill. usually I have to baby it depending on if someone else is filing up or not what the fill rate is from the pump.  Too fast it cuts off the fill etc.  I try to wait until I literally can hear it gurgling in the fill tube of the rig.  yes on the cc limit... yes I put in the card again if stopped at $100 until It really stops (and yes may only be a couple dollars more) ... though most places have at least raised the limit to $150+ now thankfully. And I love Costco fill ups.. additional 3% off  if using the Costco Amex card.
Tina
 

Yes for fuel gauge as well.  Mine is full way over full mark pegged to right side, first 100+ miles makes no dent, but at half is in reality down 2/3 or more to 25 gal or so. 80 gallon tank.  Keep track of miles....  Once mine clicks below half I look to fill up....

K&N E1500 seems like matching. I had always a K&N in my cars. Like them.

the next fuel stop was once again 7.5 mpg but since then the fuel prices dropped from $3.2 to $2.30 (with my discount card) the cost per mile dropped significant.
And for this low price I can get the rig fueled up in two session without sliding the card three times: :)clap

Yesterday I cleaned the Air-Intake and ordered the K&N Filter, about $45 at amazon. The normal paper filter would be $20 with shipping, and had to be replaced after 12k miles. the K&N only after 50k cleaning. Will probably never drive this far with this Motorhome so - lifetime investment and the option to clean it on the road instead of carrying a spare-part.

I have to get the whole thing on a scale. The MH should have about 12000lbs empty + 6000lbs for the full load trailer

My old Itasca pulling my race car trailer only got 4 to 6 mpg, and that was with a good tune on the engine. It had 4.56 gears in the rear end and 16" wheels. The best I ever got on that rig was 8 mpg not pulling a trailer. It had duel exhaust put on it by the PO and was in very good shape. My currant coach does so much better, 8 to 10 mpg pulling the same trailer, on the same roads, about the same speed. This coach likes to travel at a faster speed than the older coach, don't have a tach so I don't have any idea what the rpms are. This coach has a tbi injection,overdrive trans and 5.38 gears in the rear, with 19.5" wheels but is about the same height as my Itasca. It takes off from a stop so much better, and seems to coast forever when letting off the throttle. I've never weighted either coach but I think this one is liter, as it has an aluminum frame compared to the steel one on the Itasca. Now my buddy has a 96 Storm with the same engine and trans, but his is almost a foot taller, and about 4" wider, he gets 1.5 to 2 mpg less than I when not using the generator. He normally has to run his generator because his wife is in poor health and he has to run the ac, so he's back down to 6 to 7 mpg. Wind resistance is the largest factor with these things but so is rolling resistance.

Tina, if your coach looses mileage when the weather is cool, putting a free flowing filter may have hurt more than helped. That tells me your coach is running lean, and that will kill the mileage too. Most coachs from the mid 70s to the late 80s were calibrated to the lean side for emissions, and using enhancements just make it leaner. I'd almost bet that if the carb was richened up the fuel mileage would increase.   

I've also got the 19.5 tires and the Overdrive transmission, It's really nice to drive and like you said coasts forever.


I tell my navigator (wife) to tell me about one mile before we have to turn to say it to me, and if there is no traffic behind me , I just release the cruise control and coast it.
This thing is rolling still about 30 mph when I'm coming down from 55 in flat terrain.


Yesterday I installed the E-1500 K&N and will keep logging how it affects the mpg. Since I'm living and driving in Flat South Florida there should be some measurements possible.

I actually got carb icing using the naked KN assembly... the Banks Torques headers on now as well as the original manifold have a backfeed pipe from exhaust to carb just to correct that... we had blocked it off since the naked assembly although very cool looking did not have an input for it.   Gone came with a Holley carb but it was warped so was immediately replaced as first on check list in winter of 2005 with a new edelbrock which has been adjusted and the engine retimed when we put the original snorkel with the KN on.  6.4-7.4mpg with an 8 here or there are the best I've done.  Easy on the gas pedal and I don't open those secondaries too often unless need serious billy goat power.    19.5" tires.. tranny I don't believe has over drive though. 

Do you have one of these? https://images.search.yahoo.com/images/view;_ylt=A0LEVjGXJYtUmdsA6ocPxQt.;_ylu=X3oDMTBsa3ZzMnBvBHNlYwNzYwRjb2xvA2JmMQR2dGlkAw--?p=edelbrock+calibration+kits&back=https%3A%2F%2Fsearch.yahoo.com%2Fyhs%2Fsearch%3Fp%3Dedelbrock%2Bcalibration%2Bkits%26ei%3DUTF-8%26hsimp%3Dyhs-001%26hspart%3Dmozilla&w=555&h=371&imgurl=www.carid.com%2Fic%2Fedelbrock%2Fengine-components%2F1480_1.jpg&size=29KB&name=1480_1.jpg&rcurl=http%3A%2F%2Fwww.carid.com%2Funiversal-fuel-systems%2Fedelbrock-calibration-kit-for-performer-series-carburetors-21720233.html&rurl=http%3A%2F%2Fwww.carid.com%2Funiversal-fuel-systems%2Fedelbrock-calibration-kit-for-performer-series-carburetors-21720233.html&type=&no=8&tt=120&oid=8acfca3121249c6719fafedf95849f82&tit=Edelbrock%C2%AE+-+Performer+Series+Carburetor+Calibration+Kit+for+1407+...&sigr=13khp2uln&sigi=11n1apjr3&sign=10a7qfkpt&sigt=103vg5ole&sigb=136gtuirc&fr=yhs-mozilla-001&hspart=mozilla&hsimp=yhs-001 (https://images.search.yahoo.com/images/view;_ylt=A0LEVjGXJYtUmdsA6ocPxQt.;_ylu=X3oDMTBsa3ZzMnBvBHNlYwNzYwRjb2xvA2JmMQR2dGlkAw--?p=edelbrock+calibration+kits&back=https%3A%2F%2Fsearch.yahoo.com%2Fyhs%2Fsearch%3Fp%3Dedelbrock%2Bcalibration%2Bkits%26ei%3DUTF-8%26hsimp%3Dyhs-001%26hspart%3Dmozilla&w=555&h=371&imgurl=www.carid.com%2Fic%2Fedelbrock%2Fengine-components%2F1480_1.jpg&size=29KB&name=1480_1.jpg&rcurl=http%3A%2F%2Fwww.carid.com%2Funiversal-fuel-systems%2Fedelbrock-calibration-kit-for-performer-series-carburetors-21720233.html&rurl=http%3A%2F%2Fwww.carid.com%2Funiversal-fuel-systems%2Fedelbrock-calibration-kit-for-performer-series-carburetors-21720233.html&type=&no=8&tt=120&oid=8acfca3121249c6719fafedf95849f82&tit=Edelbrock%C2%AE+-+Performer+Series+Carburetor+Calibration+Kit+for+1407+...&sigr=13khp2uln&sigi=11n1apjr3&sign=10a7qfkpt&sigt=103vg5ole&sigb=136gtuirc&fr=yhs-mozilla-001&hspart=mozilla&hsimp=yhs-001) If you play with the calibration you should be able to get your mileage up to at least ten if you are driving lightly. It would also help to put in an air/fuel meter so you can see how it is running all through the driving range and to help you set it up.

since I've got no Carb - no issue with that.The TBI is a nice system, noisy but good. Going to somewhere - where it's cold - no thanks, I love Florida and only travel North in Summer when it's warm.


I never had a car with Carburetor and I think I don't want one.  They make injection since the 40s, why should I bother ? Even electric injections is around since the 50s.

Rick... no I don't.. hmmm guess I have to figure out which kit I need though.. or is the one you hyperlinked the one I need?  1987 454?  I'd be in uber heaven if I could pull 10 out of her... then I could extend trips as we budget one tank out one back... $3.87 is as high per gallon as paid thus far... and she is full up right now of course now that gas in MD is $2.47 paid today at Costco...

With a carb you have to be spot on for decent fuel mileage, and when the weather changes, you're not spot on anymore.

With injection the pcm constantly makes changes so it is much closer. By adding more air you have to add more fuel so the mixture is correct, don't matter if it's carb or injection. I know when I added the cold air kit to my Corvette the performance increased, but my fuel mileage went down a bit. That didn't bother me too much because it does real good on mileage anyways.

On my MH I just make sure it is tuned up, and let the pcm do the rest. Changing the dist cap and rotor at least every other year to me is a must. If your cap is more than a year old, check it, I'll bet it has corrosion on the terminals. I use the brass terminal cap from NAPA, but they still corrode. GM has always had this problem, but I suspect all manufactures have the same problem. They can be taken apart and cleaned, but if you take too much off it'll cause a misfire, so I just replace them.

Tina, the kit I linked to was for the 1407 Edelbrock which is what you should have on there along with a Edelbrock Performer manifold. An Edelbrock is infinitely adjustable in all of the power ranges so the oxygen sensor makes sense for setting it up absolutely perfect. It is not al all required but just a nice edition and not all that pricey. Your Banks headers may already have a boss for the O2 sensor.

For those of you with deep pockets, the new TBI style Fuel Injection system might interest you

http://www.quickfueltechnology.com/ (http://www.quickfueltechnology.com/)

Dave

Okey guys, there is no way that our rigs can get every 15mpg,

There are two things which are in the way, the quadratic size of the front which is in the wind the and the drag (http://www.dict.cc/englisch-deutsch/drag.html)coefficient (http://www.dict.cc/englisch-deutsch/coefficient.html) (0.4) . Both are simple old and not aerodynamic.
Why have the newer rigs better mpg ? It is most likely not the engine, it's the much better aerodynamic.

Just did the math and with our rigs it is pretty much impossible to get better then 10 mpg @ 55mph  (cruise speed)

The one thing you can not change is the quadratic surface of the front,  but we could play around at the drag coefficient.
Do you all see the surface of all the new rigs ? no awning is standing out, no tires are mounted to the back, everything nice an flat.
Even the underbelly is completely clean.  (Diesel pusher setup)

So if someone is running near 10mpg, that's the best what a natural aspirated engine can do. If you getting more, then you are most likely driving under 55mph.

Ah ha I have a class C chevrolet frt end (fiberglass) Also have vortex generators on the rear to elimiate drag , The flat part of the frt is sloped and smoothed (window removed) I have not done anything to smooth the undercarriage but thats not impossible . Actually  12 MPG would be acceptable   that would equal 600 miles per tank full of fuel  . (see veh pics in projects )  Frank

I agree, I think 15 mpg is just a dream even for a class C. They may even be worse for the areo than a class A. Every one I've ever owned handled much worse than my class As, and I've had 4 of them by the 3 manufactures. The Ford chassis was by far the worst. I would not go thru all the trouble going to FI and overdrive on an older coach as you could not possibly recoup the cost to do so. TBI does indeed improve fuel mileage no matter what some people think.  Try to remember back before FI, most 1/2 ton pickups and cars didn't do much better than 10/11 mpg. Plus drive ability  is so much better. I have never spent much trying to get better mpg on any vehicle, I just make sure they are in the best tune they can be.

With 4:10 gears you are already ahead of most of us with 4:56 gears. On my last trip I got over 12 MPG towing a 7500 lb. trailer in hilly country at 60 MPH. It can be done. That is with all of the stock equipment, I haven't changed anything out yet but I will be. That mileage was figured by hand and on a GPS.

So my last tank had been: 7.32 mpg  withhorse-trailer, fully loaded through hilly terrain and unfortunately a lot of stop and go, three hours of idling to recharge the batteries because my generator quit working, A/C on most the time.


After this tank-stop I installed directly the K&N Air-cleaner. The old one was pretty dirty. We will see how the next tank will be.

If your getting 12 mpg Rick, I wouldnt touch that motor W%

so the K&N starts doing it's wonder:


8.65 MPG

Just kidding, was driving without the horse trailer - but much faster 65 mph.

Quote from: 89Elanden on February 26, 2009, 10:13 AM
We have a 37 ft. Elanden with the 454 and have never gotten more than 6 mpg, 5 mpg is the standard, this is just a fact I have had to accept. After numerous trips, short, long, flat, mid summer, winter, regardless the mpg never varies much above 5 mpg. I once discovered a fuel leak at the fuel pump and just knew my mileage was going to double, no dice, apparently it only leaked while ideling, I guess at speed the fuel demand from the engine drew the fuel up the line so very little actually was lost. I have never weighed the rig, but we never carry fresh water, or full holding tanks, tire pressure is always monitored, clean air filter, oil changed regularly etc. It just is what it is 5 mpg, thankfully gas is not 4 bucks a gallon anymore.
Rick aka 89Elanden

Thanks for the honesty

Our 32 ft Elandan gets 6.5 mpg (and only because it is 5 ft shorter)  Head wind..... Tail Wind .....55....65....75...up hill .....downhill its always the same. With a low geared rear end ratio you can drive any way you like........you cannot change the MPG. I disagree with the notion that driving habits make a difference.

Ohh by the way just for the purpose of full disclosure........the 6.5 was on the US Gallon. On the Canuck gallon which is 160 oz to the US 128 I get 8 :)

since I'm from europe I grow up with how many lites per 100km.
miles per gallon makes it hard to compare since its a equation which goes to indefinitely around zero.


6 mpg equal 39L (11 gallons) per 100km (70 miles)
7 mpg equal 33L per 100km
8 mpg  28L
9 mpg 25L
.
.
14 mpg 15L
.
.
24 mpg 10L


we got on 5000 miles with our 18 ft Horsetrailer about 7.5 miles a Gallon with 19000  lbs total on the scale. I did open up the factory cold Air intake and installed a K&N airfilter. Plus good spark Plugs and 8mm silicon cable.
Fres Oil every 4000 miles.

the only Motorhome in Europe I have driven was a Class C Type and it needed about 14mpg  15L/100km and we could drive this thing with 100 mph !
For Europe it was huge... here It would be not even a Mini Winnie :P  Over there I would need a Semi/Commercial drivers license to drive a MH big as they are here.

Just returned from a 3000 mile round trip after having Head Gaskets and Waterpump replaced. Best Gas mileage I have ever had. Between 7.5 and 8 .....8 on the flats.1985 32 ft Elandan.

about normal.. 7.4 is my average.... Banks, no AIR, full tune up.  28ft. about 14K loaded with empty waste tanks and 10gal FW.  60+ gal fuel in 80 gal tank.

I'm tracking the mpg's for my 31' HRC Aluma-Lite XL here: 


http://www.fuelly.com/car/chevrolet/p30/1990/tmsnyder/454843


This is a 1989 454 with two air pumps removed, distributor re-curved, exhaust flow restrictions removed, Edelbrock 1406 carburetor.

With my RV and trailer boat with gas 8.5 mpg and with LPG 7.8 mpg, in Italy gas = 1,5 â,¬/litro and LPG = â,¬ 0,5 â,¬/litro

Quote from: coltronicola on September 09, 2016, 01:05 AM
With my RV and trailer boat with gas 8,5 mpg and with LPG 7,8 mpg, in Italy gas = 1,5 â,¬/litro and LPG = â,¬ 0,5 â,¬/litro

How many liters are in your gallon in Italy?

hi Tmsynder, 1 litro = 0,26 gallon

'89 HR and we have put 10,000 miles on it since the 2.5yrs of owning it.  It has a total of 35,000 miles on it and still has the AIR system.  I've rebuilt the carb, new wires and plugs. 

We have 6 kids and tow a 4 X 10 trailer for 5k of those miles.  Spent two months and 15 states living out of it and have documented every gallon of fuel used.   

Highest 8.6mpg
Lowest. 5.3mpg
Average 6.8mpg


I drive around 65-70mph wife does 55-65mph. 

yup.. highest was 10.1 I think (downhill in a hurricane) LOL... difference between how its parked when filled up and who does the filling....
lowest 3.2... freezing conditions with snow had put a naked KN filter assembly on with no exhaust recycle to carb.. iced up....

Average... KN, no AIR, edelbrock quad, Magnaflows 2.5" dual, silicone racing wires, new cap/rotor, 2 ignition control modules, 7.2mpg avg.. no toad, kids have fur about 300+lb of them on board every trip.  88K or so on the ODO now.  10 yrs of mileage data every gallon in calculated, bought it with about 67K on it.   MD, VA, DE, NC, PA, OH is the limit of where we have taken her.... 

AVG is 6.6 over the appalachians MD to Breezewood but 7.6 from there to OH... and 7.4 haul back... 

It would be interesting to see others log their fuel mileage on fuelly.com as I did above.   That way we can see all the data.


Fill ups are super easy, just one text into fuelly and it updates the logs.

Thought I'd look into this topic again,... but it's been rather quiet.

I do keep full 100% records of fuel and mileage. And for last 4000mi of this year in Cruise Air II,... a high of 6.6mpg and a low of 5.6mpg. those extremes are of long durations of relative speed. Lower speeds of duration,... higher mileage.

Now,... the trends I see myself, here among others, and those elsewhere.

The greatest influence in mileage, is SPEED! Seems nothing affects your mileage more,... the frontal load of wind may vary a bit among styles, but speed increases the frontal load inversely for everyone. Seems the variations of frontal designs have only a small effect on mileage. And EVERYONE has a similar drag since there's very little variation here. How much drag??? Enough to easily suck up a small car right up to your rear bumper!!! And the same power is holding ya back as speed increases. The combined load of wind resistance and drag can easily exceed the vehicle weight. Short light "boxes" see little difference if any, from longer heavier "boxes". It really doesn't take much to get an RV rollin',... a couple strong backs can push 'em a few feet in neutral regardless of size. But at speed,... your engine is gonna work hard and eat fuel!!!

Biggest improvement for mileage? Newer computerized fuel injection systems! More than any other modification of gear ratios, exhausts, intakes, trans, overdrives, or anything else.... seems obvious that those with fuel injection can see an EASY 10-20% or even greater improvement of mileage over an identical carbureted model with an unskilled pedal-pusher. NOW,... many mods will significantly affect and generally improve POWER, but it takes the same amount of power to move your RV against the resistances encountered. And that means no real improvement in mileage. A 700hp engine will require less pedal effort and can attain a higher speed against load resistances,... but mileage at a set given speed will still be the same as an OEM stock model. Drive at 7mph for an hour, and most will use about a gallon of fuel (unless your AC is on for that hour,.. then you'll use another gal!). Tow the same with your 20hp garden tractor for 7mi,... and you might be surprised to see the same mileage!!!

And diesel vs. gasoline,.... that's apples n' oranges!!!! The available energy in a gallon of each is significantly different, but it still takes the same energy to move a given load. Per gal,... diesel has a lot more, and you'll generally see a greater mpg.

Oh,.... and a good tune-up, can significantly affect mileage. Ya got a plug fouled and missing,... then the fuel mix running thru that cylinder is doing nothing but creating an added load. Subtract the mileage it was capable of.

Anyone see differently???? How many see a difference depending on WHO's driving??? Lol!!!

We completed a 1100 mile round weekend trip and as I stopped for gas, I calculated mileage as I had never done this before. Were driving a 1994 Winnebago Warrior 25' with the 454 and 4l80E
At roughly 12,000 pounds or a little more, and mostly flat terrain at 70 mph, I averaged 10.51 mpg.
At 60 mph and hilly terrain (rolling hills South of Rolla, MO - not mountains), I averaged 9.31 mpg.
Lastly, at 75 mph and mostly flat terrain I averaged 9.56 mpg.

KC

What type of Fuel injection do you have And what is the RPM @ ea of those speeds ?  That is pretty fantastic MPG  Frank

Quote from: lexadmn on April 02, 2017, 08:11 PM
We completed a 1100 mile round weekend trip and as I stopped for gas, I calculated mileage as I had never done this before. Were driving a 1994 Winnebago Warrior 25' with the 454 and 4l80E
At roughly 12,000 pounds or a little more, and mostly flat terrain at 70 mph, I averaged 10.51 mpg.
At 60 mph and hilly terrain (rolling hills South of Rolla, MO - not mountains), I averaged 9.31 mpg.
Lastly, at 75 mph and mostly flat terrain I averaged 9.56 mpg.

KC

I have a 1994 winnebago  warrior   22 foot 454 engine ..is your engine fuel injected ? I wonder what type of gas mileage   I will get

Yes, the 454 is injected, just a throttle body with no smog.
I use the cheapest fuel I can find - 87 octane. I am not loyal to any fuel company, just what is available - Pilot, Flying-J, BP, etc., whatever is close to the Interstate.
No idea of the rpms, I have never done the math. I do know I have 4.31 gears, 16" wheels with P235 tires.

4.30:1 is a ratio I have not heard much of. 4.11, 4.27, 4.56, 4.88. are the most common gearing's. 4.27 was used mostly in older Jeeps.

I guess the 4.30 is something they are using to match up with the overdrive transmissions and apparently it is working. That is some good mileage figures for 12,000 lbs. and at those speeds.

We was told it was fuel injected ..but my husband said it looks like a carburetor . .is there a carburetor  and fuel injected   ? Somewhere we saw where it said it is a 93 chevy but somehow the body is a 94 so not sure what that classifies it as ..lol so all 454 chevy chasing are fuel injected or just certain ones

Quote from: lexadmn on April 02, 2017, 08:11 PM
We completed a 1100 mile round weekend trip and as I stopped for gas, I calculated mileage as I had never done this before. Were driving a 1994 Winnebago Warrior 25' with the 454 and 4l80E
At roughly 12,000 pounds or a little more, and mostly flat terrain at 70 mph, I averaged 10.51 mpg.
At 60 mph and hilly terrain (rolling hills South of Rolla, MO - not mountains), I averaged 9.31 mpg.
Lastly, at 75 mph and mostly flat terrain I averaged 9.56 mpg.

KC

This is GREAT!!!!
Your figures clearly show the importance of speed,... jus 5mph can mean a difference of 10% in mileage. At higher speed, drag is HUGELY significant, and jus can't be overcome or effectively reduced.


And you gave good figures for others to compare in regards to fuel injection, given a similar engine, vehicle size and weight.


If I were to have guessed,... I would have expected you would have about a 20-30% improvement over what get, all considered, and would have estimated 7-8.5mpg. Your mileage is GREAT and slightly better than I would expect, especially at speed.

Quote from: Winnebago Warrior 94 on April 03, 2017, 10:12 AM
We was told it was fuel injected ..but my husband said it looks like a carburetor . .is there a carburetor  and fuel next ? Somewhere we saw where it said it is a 93 chevy but somehow the body is a 94 so not sure what that classifies it as ..lol so all 454 chevy chasing are fuel injected or just certain ones

Our chassis is a 93 as well and the coach is a 94 (like yours) and it is fuel injected. As DaveVA78Chieftain posted, I suppose the throttle body could be mistaken as a carburetor to someone that is not at all familiar between the two.
I posted a pic (above) that shows what the fuel injection throttle body would look like.

KC

Actually my Challenger with the throttle body injection did better on fuel than the Daybreak with port injection. It also had more pep from a stop sign, not that I pushed them much. I would have thought just the opposite looking at the body shape. The Daybreak sat lower to the ground and had the slanted nose, so I thought that it would have cut the air better. The Challenger had 35,000 less miles on it too. 

Thanks for yalls help ..I hope my winnebago  warrior  gets as good of  gas mileage   or or a little better being as mine is a 22ft ..my hubby didn't open the top on what he said looked like a carburetor . .he just noticed it when he was changing the air filter..I don't know alot of proper mechanical  terminology . .but I don't mind getting  my hands dirty and I like to know and find out info about things ..I did change out the wiper blades ..lol :)clap 

That's probably the most important. It doesn't matter how well it runs if you can't see where yer goin'   :)

Quote from: Elandan2 on April 05, 2017, 07:33 AM
That's probably the most important. It doesn't matter how well it runs if you can't see where yer goin'   :)

good one  :D  and true story ...lol.I also called Chevrolet  and they said it is fuel injected I'm ready to check out the gas mileage . .I need to get insurance  and get it inspected   

A lot of lessons learned here, summed up nicely regarding mpg's:

https://rv-roadtrips.thefuntimesguide.com/rv-gas-mileage/

We went on a 1600 mile trip and averaged 7.23 MPG. I don't think that's too bad as there was 4 of us and we were loaded up pretty good.

That seems about right, but I don't put much faith in anyone's numbers unless I can see all the data.   Mine are here: http://www.fuelly.com/car/chevrolet/p30/1990/tmsnyder/454843


Set up an account and every time you fill up, send a text to fuelly with the odometer reading and the # gallons.  It's very easy, and free.   And then we can all see what fantastic mpg's everyone is getting LOL  Otherwise I'm a skeptic.  Mid 7's is realistic.  But double digits? Show me the data.


It's very common for someone to calculate their mileage based on one fill-up after driving only a few hundred miles, gently, downhill, with a tail wind and all the tires fully inflated.   Then claim that that's their mileage while they hammer down the road at 75mph, into a headwind, with tires they haven't checked in months still claiming  'Oh yeah, I get 13mpg!'

We took our first long road trip just before Christmas in our 1995 warrior 23. 1367 miles RT.  Used 140 gallons of fuel which works out to about 9.7 MPG.  ~Flat roads and 90% interstate. Cruise set  mostly on 65mph. 15-20 gallons fresh water. Two people and a 20lb dog.  Prior to the trip all plugs/wires cap/rotor were replaced. TBI system cleaned and serviced. Tires ~77 psi.

Quote from: RickNC on January 03, 2018, 12:08 PM
We took our first long road trip just before Christmas in our 1995 warrior 23. 1367 miles RT.  Used 140 gallons of fuel which works out to about 9.7 MPG.  ~Flat roads and 90% interstate. Cruise set  mostly on 65mph. 15-20 gallons fresh water. Two people and a 20lb dog.  Prior to the trip all plugs/wires cap/rotor were replaced. TBI system cleaned and serviced. Tires ~77 psi.

At 23' your weighing in around 10k?? I would say your at the "optimal" mpg for a P30 chassis rig, due in part to not weighing a lot and having TBI and you probably have overdrive?
But on 14,000lbs +/- a 1,000, a carburetor, and a TH400, your back to 5-6.5 mpg depending on how/where you drive and what you are towing. That's been my experience anyway, out in the wild west.

1994 23’ Brave with 454 Chevy and Banks Power Kit and going from Vegas to Chicago I was able to get 11.6 MPG and when I ran the foothills in Missouri I was at  10.2 MPG ..... For sure my best mileage came when I traveled about 55 MPH

Quote from: legomybago on January 03, 2018, 05:54 PM
At 23' your weighing in around 10k?? I would say your at the "optimal" mpg for a P30 chassis rig, due in part to not weighing a lot and having TBI and you probably have overdrive?
But on 14,000lbs +/- a 1,000, a carburetor, and a TH400, your back to 5-6.5 mpg depending on how/where you drive and what you are towing. That's been my experience anyway, out in the wild west.

I'm still curious what the gross weights are, and if these rigs have overdrive with fuel injection. At least overdrive?....

Overdrive can be a double edged sword. It can give better mileage on flat ground with no headwind but it is generally dropping the engine down pretty low in the power band so you will be lugging the engine on hills and into the wind and therefore using more gas there.

My 94 Winnebago warrior is fuel,injected and not sure about the overdrive ..not sure about the gas mileage but I will be finding out soon ..I got my belts changed today and I got my new awning installed and transmission fluid and filter changed ..I drove it. Around 65 miles and used less than a 1/4of a tank .. :) ..I do need to get me some new tires especially on the front ..mine are 2007 ..so time for new ..next will be,my paint job ..ylpee

hat is only 260 miles per tank roughly according to the gauge so don't get your hopes up to high. That said you cannot base your mileage on the gauge, you have to go by fill ups and true mileage ideally from a GPS. And you have to do it over several fill ups. On a 94 you probably do have overdrive.

And you may have to correct for your odometer.   Easy to do, just note the odometer reading as you pass a mile marker.   Then after 100 miles or more, see how far off you are .  Then correct your odometer reading.   Especially if you changed tire sizes (diameter) it can be off.



Biggest factor though is you have to drive some significant miles, not just a couple hundred.

We just did a trip to Florida and back to Buffalo, over 2500 miles and got the following on all my fill-ups. 


6.76 mpg
7.32
7.79
7.73
7.76
7.43
7.80
7.38
7.53


This is a 454 chevy, edelbrock carb, recurved distributor, towing nothing, 40 gallons of water in the tank, and I drive between 60-65 mph.  All except the first one was highway, pretty hilly along some sections of the route. 


All the data are here: http://www.fuelly.com/car/chevrolet/p30/1990/tmsnyder/454843 (http://www.fuelly.com/car/chevrolet/p30/1990/tmsnyder/454843)


Average over the 13,458 miles for which I've logged every drop of gas is 7.3 mpg.

Just as a sanity check to put my mpg numbers in perspective, I was wondering what is the Maximum possible mpg I could ever expect from my motorhome.  It's actually a fairly simple calculation.  I assumed:


Air at stp
No other hp losses, just air resistance.
8' wide by 9' tall front area
Flat road


Different shapes experience different resistance to air flow, and this is quantified as a drag coefficient.  I  considered worst case though best case.  Worst case = a brick shape, Cd=1, this is pretty much what I have.   Modern cars can get down to 0.3 or so, my RV is nowhere near that, it does have a little bit of a sloped nose.  Best case, I only took it down to 0.6.  I can't imagine an RV having a better Cd than 0.6.


For engine efficiency, there are published values for how many lb/hour of fuel are burned per hp made by the engine.  For gas, they vary from 0.45 to 0.50.  This would be for an engine that is in tune and well maintained.   If not, all bets are off obviously.


By my best SWAG (scientific wild a$$ guess), I'm thinking my Cd~0.8, and engine is about 0.47 lb/hr/hp, I could only ever see 8.5mpg at 60mph.  That's the max mpg I could ever get from the rv just considering air resistance, no other frictional losses.  I'm getting 7.5mpg now, so even if I spent a bunch of money on engine mods, I'd be running up against this hard limit to fuel economy.  I was thinking about installing a wideband oxygen meter to check on my carburetor tune, but now I'm reconsidering it.  $200 to try to eek out a few tenths of an mpg doesn't seem worth it.


It resulted in an interesting plot that came out of the analysis, I'll try to post it.   It verifies as mentioned many times in this thread that if I'm willing to drive slower, the mileage can increase. 


One way to change the Cd of the motorhome might be to change the shape of the air flow around the back end of the coach using airtabs.  They are about $200 for a set.  Without them, the whole back end of the coach is a large low pressure area, pulling back on the coach.  Airtabs are supposed to disrupt this and create a shape behind the coach similar to the trailing edge of an airfoil.   Kind of like the fold-out shapes on the back ends of tractor trailers that you find on the interstates these days.  Might be worth trying them out, there are some threads on this website that claim that they do actually work.

They do work but make SURE you put them on in the right direction!! They do NOT go the way you would think they do.


And that drag coefficient is figured at sea level and 75 degrees and 45% relative humidity and no wind so transfer all of that to real world figures where you will very seldom, if ever, see those conditions your figures are probably pretty close to the mileage that you are getting right now. I am impressed with the consistency of your mileage, it is very close on every tank.
I have to start from scratch on my distributor and timing settings again this year. I also need to buy a new advance timing light. I like the quadrajet but I think I am going to go with a Performer manifold and carb, That carb is just so much more adjustable. And that way I also get rid of the EGR and all of the associated passages and crossover heat.

That sounds like a fun project! 


I want to play with my edelbrock too, with an O2 sensor to try to milk some more mpg's out but based on my fluids calculations there's not a lot to gain there just based purely on wind drag. 


Maybe a Duramax swap, or that 7.3L you have .... :)

Fuel Injection... 94 Brave, 23’ ..... 464 with Banks Kit ..... Best mileage at 60mph 11.6 ..... Average in Mountains of Missouri 10.2

Kept it 60 mph or less and drove another 660 miles this weekend.  Usually I ran it at right around 58 mph.  From Buffalo to Syracuse (flat), down through the Pocono mountains with some pretty good hills, and back.


8.6 mpg
8.2 mpg  (some of this was running the generator about an hour)

Fleetwood Southwind Storm 28ft 454 TBI w/4L80E trans


Renton Highlands, WA. to Blaine, WA. I netted 8.75 mpg with an average speed of 58mph. Overdrive in these rigs is a bit of an oxymoron. I usually just keep it in D due to the hills here. It does just fine MPG wise. No towing.


The best I netted was from Renton Highlands to Medford, Or. with a 10.04mpg. A lot of flats. Speed again at 58mph. No towing.

I have to say I've enjoyed reading this thread, and can't wait to reveal my MPG when the fuel system is back together.


Something not many of you have mentioned is what Octane rating are you all running? In Colorado, we have 85-87-89 available at most pumps. Now check this out, the label of a lot of P30 Chevys strictly say, FUEL REQUIREMENTS - USE 89 OCTANE OR HIGHER" This from the P30 Chassis manual page 7-92. My 89 454, and many others I'd assume says to run 89 octane!


What say you? I've always put 85 in to save a few bucks but this could be relatively important right? I suppose it depends on your locale. 

The cheapest stuff available!  Yes I ran a bunch of 85 octane last summer on our 8000 mile loop out west and back.

You mean 87 Octane?


There's no way I would run E85 in one of these. I couldn't imagine it would run at all well, and if it somehow did, you would ruin the fuel system in short order. These were not designed for ethanol fuels. 10% ethanol is pushing it already, any more and you're just asking for trouble.

Oh yeah, 85 octane all day long.  Cheapest stuff they had.  Makes no difference in MPG, only problem would be preignition and I never heard any of that.  These are low compression engines, it doesn't need high octane. 


I do worry about the ethanol attacking fuel system components, so when I get home I arrive as empty as possible and fill up with ethanol-free, drive it around a bit, run the generator, and park it. 


Ethanol actually _increases_ the octane of gasoline, it's 113 octane on its own.   So if they are selling 85 octane with 10% ethanol, it would actually be lower without the ethanol, about 83 octane.

Quote from: 87Itasca on August 09, 2018, 01:47 PM
You mean 87 Octane?


There's no way I would run E85 in one of these. I couldn't imagine it would run at all well, and if it somehow did, you would ruin the fuel system in short order. These were not designed for ethanol fuels. 10% ethanol is pushing it already, any more and you're just asking for trouble.

Definitely like to avoid ethanol based fuels. What you're saying is Ethanol is being used to affect the octane rating of gasoline?  oh wait, I see. No, definitely not running E85 AT ALL!

Quote from: tmsnyder on August 09, 2018, 02:37 PM
Oh yeah, 85 octane all day long.  Cheapest stuff they had.  Makes no difference in MPG, only problem would be preignition and I never heard any of that.  These are low compression engines, it doesn't need high octane. 

That's what I thought!  Hm?  Why do you think the label specifically says run 89 or higher?

I'm no 454 expert, but..


You should get better gas mileage and more power with the lower octane gas..


In gasoline the octane is artificially increased with additives..
The additives serve to slow down the burn of the fuel and increase it's resistance to ignition..
Higher octane gas is harder to ignite and burns slower.. This is needed for high compression engines and forced induction engines.


Ethanol burns even slower, has a much lower energy density, and is much more resistant to ignition..


Ethanol burns so much slower that flex fuel applications run a lot more ignition advance with high ethanol content to get peak cylinder pressure back near TDC.. You have to fire the sparkplug earlier to get it burning right before the piston gets to the top vs straight gasoline..


Ethanol contains much less energy..
""
A.  76,000  = BTU of energy in a gallon of ethanol[/size]B.  116,090 = BTU of energy in a gallon of gasoline
""
""[/size]Ethanol[/size][/font][/size] and fuels like E85. 1.5 gallons of [/size]ethanol[/size] has the same [/size]energy[/size] content as 1.0 gallon of [/size]gasoline[/size]. A flex-fuel vehicle will experience about 76% of the fuel mileage MPG when using E85 (85% [/size]ethanol[/size]) products as compared to 100%[/size]gasoline[/size].[/size]""
So all else equal you will get worse MPG on ethanol than gas because of the energy content difference..


Ethanol requires a different Air Fuel Ratio for a proper burn compared to gasoline..
(http://paulsvang.com/mylife/wp-content/uploads/2016/04/air-fuel-ratios.jpg)


As you can see gasoline has a stoichiometric ratio of 14.7 parts air to 1 part gasoline while ethanol's stoichiometric ratio is 9.8 parts air to 1 part E85..


So you need more ethanol for the same amount of air to get a proper fire than you do with gasoline..


Flex fuel engines have a computer that sees the ethanol content of the fuel, via a flex fuel sensor, and sees the AFR of the burnt exhaust, via O2 sensors, so the computer can add more fuel at the same amount of airflow to get back to stoichiometric with changing fuels..


Carburetors don't do that, they are tuned for a specific fuel type..
If you run ethanol in a carb tuned for gasoline then you will be mixing the same amount of fuel when you should be adding more and you will be lean..


You can tune a carb for ethanol though, but then it will be pig rich on gasoline.


Back to octane, octane is the measure of resistance to ignition.. It's easier to catch low octane fuel on fire basically.. E85 having an octane rating somewhere around 100-110 octane, so it is harder to catch on fire..


High performance engines at times need high octane fuel to keep it from catching on fire before the sparkplug catches it on fire on purpose..
Sometimes the fuel mixture can catch on fire in the cylinder way too early and then you have a huge explosion while the piston is still coming up, fighting it, and can cause catastrophic engine damage..
This can be from a glowing hot spark plug or just too much heat in the air when it is being compressed.. So you need higher octane to make sure it doesn't catch on fire on its own before you want it to by firing the sparkplug..




Regular gasoline displays these same features with increasing octane rating but to a lesser extent than going from gasoline to ethanol..




If you don't need high octane to keep your fuel from catching of fire before it is supposed to because you have you engine so hopped up, then you will get more power and better MPG with the lowest octane fuel your engine can handle..


the lower the octane the better unless you have a problem and need to make it harder to ignite..
Modern high compression engines and turbo/supercharged engines (which really just increase the dynamic compression ratio, FI)




So yeah, run that low octane crap in your low compression 454 for the best MPG and power..
Unless you hear it pinging/knocking, then you probably have carbon deposits on your head/piston top/valve surfaces that keeps glowing hot in between power strokes and/or increasing your compression ratio (taking up volume)..
In that case pull your heads and clean the carbon out of there, or try some magic that may or may not work like seafoam..
An engine will usually knock at peak torque RPM and lower..
You know that sound when you turn your distributor too far and it starts firing against the engine.. That's the sound to watch for..


Water injection is a darn good way of cleaning carbon too.. Steam clean..

A good way to clean the carbon out of the cylinders is to force feed it water. Take the air cleaner off and get a 2 liter bottle of water. Warm the engine up to operating temp and then holding the water bottle in one hand and operating the throttle with the other, start raising the rpm and as you do start pouring the water down the carb. You will be trying to maintain the engine running at a around 1200-1500 rpm but you want to keep increasing the throttle and increasing the water as you do. This will keep the engine at the rpm mentioned. You don't want to open the secondaries but you do want to be close to full throttle on the primaries. Do this for about 15-20 seconds and taper off the water as you bring the throttle back. Then let it idle for a while to dry out the condensation that will have formed in the exhaust. Go for a ride afterwards to finish the drying. You are done. If you were to take the heads off at this point the pistons would look brand new, as would the heads. The one thing you have to be careful of is to not dump a whole bunch of water in and stall the engine. If it starts to stall stop the water. If it stalls and you keep dumping you can hydrolock the engine.

Isn't that a form of torture? :)rotflmao :)rotflmao :)rotflmao

Right from the manual. W%

Quote from: fasteddie313 on August 14, 2018, 02:20 PM
I'm no 454 expert, but..

learned something new today!

Quote from: Rickf1985 on August 14, 2018, 05:30 PMA good way to clean the carbon out of the cylinders is to force feed it water.

umm, wow that sounds crazy. my engine seems pretty tip top shape currently at 54,000mi

https://www.livescience.com/58117-does-gasoline-go-bad.html




Google 'companies being sued for selling water contaminated gasoline'... They are messing with the gas, they know what they are doing and they are getting busted but not near enough and the media is hush-hush about it... The gas we buy today stinks! I have a 97 Expedition, a 98 Mustang V6, a F150 v6, and none of them run like they did years ago. Since that gas crash of 08 the American people have been getting scammed and robbed blind. There was one time I actually literally pumped several dollars worth of air! I didn't hear the gurgling of fuel entering my gas spout and decided to pull the nozzle out a little bit and still didn't hear anything I pulled it out some more until I knew there was nothing coming out and I pulled it all the way out and held it up in the air with the trigger pulled as I was watching the dial on the pump rack up dollars! We are being sold watered-down gasoline, gasoline 'cut' with ethanol (which draws water) who knows what other kind of fillers are being used to rip us off, we are just being ripped off. Just like in family law, CPS, got taxes for everything under the sun, cops waiting behind every corner to give you a ticket or find some fault with you or try to take your kids away inviting your wife to divorce you and rob you blind so they can get their cut. Anyways don't get me started. I wouldn't automatically suspect something wrong with your machine is what I'm saying.


Sorry about the rant guys, I know it's my first post and it's probably tacky but I've had it with three-piece-suit-wearing badge-flashing scam artists and feel it's my duty to call them out at every opportunity.


Thank you Jesus.



By the way I thought I might add this is in no way any kind of response to mr. Ricks post above, which I thought was interesting I've never tried that... If I do try it and it works, well I'll shut my mouth LOL

PS nice to meet you guys. I have a 93 Pace Arrow that I intend to do some work on and stumbled across this forum. :)

Quote from: Rickf1985 on August 14, 2018, 05:30 PM
A good way to clean the carbon out of the cylinders is to force feed it water. Take the air cleaner off and get a 2 liter bottle of water. Warm the engine up to operating temp and then holding the water bottle in one hand and operating the throttle with the other, start raising the rpm and as you do start pouring the water down the carb. You will be trying to maintain the engine running at a around 1200-1500 rpm but you want to keep increasing the throttle and increasing the water as you do. This will keep the engine at the rpm mentioned. You don't want to open the secondaries but you do want to be close to full throttle on the primaries. Do this for about 15-20 seconds and taper off the water as you bring the throttle back. Then let it idle for a while to dry out the condensation that will have formed in the exhaust. Go for a ride afterwards to finish the drying. You are done. If you were to take the heads off at this point the pistons would look brand new, as would the heads. The one thing you have to be careful of is to not dump a whole bunch of water in and stall the engine. If it starts to stall stop the water. If it stalls and you keep dumping you can hydrolock the engine.

I did not intend for people to just go out and do this just to say they have a clean engine. This is something you do if you have symptoms of excess carbon in the cylinders like pinging when it shouldn't be or a cylinder with higher than normal compression.


Just running E10 gasoline will clean most of the deposits over time. Ethanol does have that one redeeming factor, it is a fantastic solvent. It is the main ingredient in all of the over the counter gas treatments so keep that in mind if you ever want to add a gas treatment to your car, you are probably already running it in the form of the gasoline.


Wkdemers, we have been getting ripped off by the gas companies since 1976. Ask Google to tell what happened then.  They own the government, not only here but in most oil producing countries so you are going to have to live with it.

Quote from: tmsnyder on September 06, 2016, 11:01 AM
I'm tracking the mpg's for my 31' HRC Aluma-Lite XL here: 


http://www.fuelly.com/car/chevrolet/p30/1990/tmsnyder/454843 (http://www.fuelly.com/car/chevrolet/p30/1990/tmsnyder/454843)


This is a 1989 454 with two air pumps removed, distributor re-curved, exhaust flow restrictions removed, Edelbrock 1406 carburetor.

Interesting. 86-87 Elandan, 28ft. Otherwise almost the same but no mods (yet). I think I get around 400 miles on a 55gal tank. That's about 7.2mpg. Just an estimate.

Thanks, I do like that free website and if set up with texting it's easy to send it the odometer reading and the amount of gas pumped in.   Does all the math for you and keeps track of honest fuel mpg.   I think it's interesting how it varies.   That last fill-up was actually two lumped into one b/c I didn't fill it completely on the way home, tried to arrive completely empty so as to fill with non-ethanol fuel before parking it. 


Texting is just A B C D where A is the vehicle ID (a or b, I'm tracking 2 vehicles), B is the odometer reading, C is the gas price, and D is the gallons added.   Super easy and it immediately texts back the mpg for that tank.   They are trying to push a smart phone app, but I'm sticking with text messaging.



I've since changed to a 750 cfm Edelbrock 1411.  It climbs hills a lot better now than with the 600 cfm 1406.

Thanks for replying, also from the other fellow. I appreciate it.  :)clap (forum needs a Thank You button)


I am on my way from Montana eventually down to TX, and I haven't quite made it to Colorado yet.


For you slow-goers on 80mph freeways: I really do drive around 45mph. I didn't want any idiot saying he couldn't see me. So on the top back of the Elandan, I put NAPA part... ugh NAPA's website is terrible. Insists on a a YMM/VIN before I browse the catalog. Ok, shoes on, climb up... Truck Lite part 22004Y. It's the 22-series with a gasket (to conform to the curved outer plastic) and the matching fitting for the wiring harness. You put the light up into position - use the 2nd screw down from the top vertical to reference position (see photo), mark the two fastener holes with a mechanical pencil with the lead extended (careful not to break, you only need a dot), pull it away, reduce your lead pencil to normal, and mark it better/cross it, drill a 1/8'ish hole. Drill a 1/2-3/4" hole in the middle for the wiring, and also, extend the kit wiring by 4 1/2 ft using B/R/W-colored wire (16 or 18 gauge). For drilling the center wiring hole, I use the fattest bit from the kit of those unstepped hole cutters (3x kit) from Hazard Fright, then angle it down when I've gotten to the bottom (the 'bottom' is the RV surface behind the plastic corner you are drilling through), so the 6' fish-tape will travel down more easily and pull through. See photo if I can get one uploaded. You'll run into an issue at the bottom where the beige plastic shroud inner-lip may block the fish-tape/wire, because of the clearance between it and the RV (take off the turn/brake 6x screws first, to remove the entire lighting assembly, and you'll see what i mean). Bring the tape around to the outside to bypass this, and you should be able to grab it and pull it through.


Once you do the above, check your grounds underneath, below on the chassis frame and replace the connectors if necessary. Also run new crimp wire loops (I also solder and liquid tape mine) to the end of the green ground wire, then to the screw on the back of the stock lighting assembly, not the original strip inbetween. Get rid of the strip and run another wire over to the backup light screw. The stock wiring on these is terrible. You lose ground and then the lights don't work.


But I digress. The crack-head way this was designed, means no one can see your stock red brake/turn/hazard indicators if you are towing anything or have bikes hanging off the back.


Eventually I will pull another wire from the front cab to the back, from the brake light switch, and take the brake-light system off the turn signal system, and the amber flashers will be just turn/hazard, with the stock red highs being only brake, and put a 3rd brake light below the 5x red clearance lights in the rear. I will also add the 22004R's (the red version of the amber ones I have installed) just below the amber ones, and those will be for brakes. [The clearance lights are not grounded right now until I figure out which of the original sockets is shorting to ground]


I've got the stock 16" steel wheels. I will inflate them to 75-80psi all around today. Also, I wonder about bag pressure.


I never ran with air in the bags. It was a comfy ride. When I did try air, it got too stiff, bouncy and crazy to handle. However, when I brought it into have it professionally re-aligned (prior to this I removed the dog-bones, the inner/outer tie-rods, cleaned them so they were easy to adjust, then approximated the setting just prior to having it done with the computer at the shop), I said there is too much weight in the back, but that I would be building a rack in the front, and moving weight to the front (spare tires with rims, not inflated), and otherwise some of the stuff in the back was for repairs/improvements on the RV, so as they got installed I would be losing weight/shifting weight, as well as giving a few things away.


So I'm sure he put air in the rear bags. I can check to see how much pressure is in them with a gauge. How do I know how much pressure I should have in them, though? I suspect he raised the back to get the chassis level prior to doing the alignment, and I don't want to throw the alignment off.

You will have to get it realigned once you get the weight redistributed. Any change in front ride height also changes both the camber and also the toe in. And if you change the angle of the coach from front to rear too much that will affect the castor but not too a great degree. That would just be something that would be addressed if a complete realignment was done.

Thanks.


Can you comment: I looked at the plate on the inside of the driver's door, and it says 60PSI.

I am thinking about going to 75PSI based on what I have read here.


Thanks for the information about the alignment issue. It will just have to wait until I have another $100 to sink into a re-alignment (that's how much I was charged in Billings). It took them less than 10-15 minutes, because I had done all the cleanup work, the de-rusting, greasing etc. But it's a flat rate for them. Rapid Tire in Laurel would have been cheaper (suburb of Billings).

Getting to a 14:1 or 15:1 ratio instead of 'dumping gas' at a 11 or 10:1 http://www.superchevy.com/how-to/engines-drivetrain/0510ch-carburetor-tuning-gas-mileage/ (http://www.superchevy.com/how-to/engines-drivetrain/0510ch-carburetor-tuning-gas-mileage/)


Requires merely a $600 diagnostic tool.


Other than that, parts are cheap.


Anyone handy near Boulder?

Also, I am a big fan of the NGK Iridiums. Besides pulling an existing plug, do you know what the stock/suggested plugs are in here, so I can look up the iridium replacement?


Edit: Rockauto lists 3 different NGK/Denso's: 5330 POWER, 4517 TT, and  7516 IX


Ah, it looks like the TT. The IX is the original iridium design, while the TT has a tougher ground electrode.

John, I can tell you from many years of experience that those plugs will work great in small foreign engines but for the most part they will run no better and a lot of the time they will run worse in big American engines. Ever try putting those plugs in a 4.0 Jeep engine? It will not idle and no acceleration, never fails. I run 75lbs in my tires all the way around. That is where I found that they like to run and stay at a decent temperature. I run the Samsons which do not list a weight to pressure chart but most big tire companies will give you a chart that tells you what pressure to run the tire at based on the scaled weight reading. I guarantee you are not running 10 or 11 to 1 anytime other than hard acceleration. If you were you would be belching black smoke. I don't know what diagnostic tool you are talking about but you can buy a wide band A/F meter for 100.00 and install it on your dash so you can see your mixture in real time. A 454 moving a barn down the road is never going to get anything better then 8-10 MPG and to get that you are going to have to change the cam, intake manifold, carburetor and add headers. The money that is going to cost you will buy a LOT of gas at 8 MPG so how much do you actually drive and will you drive enough to earn back that money at the extra 2--3 MPG you will gain?

Well said Rick :)ThmbUp

I started tracking my mileage on 7/7/16.   Since then I've driven it 15,738 miles.  I've spent $5730 in fuel at an average of 7.4 mpg. 


If I could get that to 8.4 mpg, it would have resulted in a $682 savings in gas.  A $200 A/F meter is on my to-do list, b/c I would like to tune the carburetor but I'm stuck at getting the exhaust pipe off and welding on the bung.  Just can't seem to get myself under there to do it.


I'm also thinking about folding up some DIY air tabs and see what that does :)


My tires are load range F, 110psi tires, I run them at 90psi.  I'm afraid to run them any lower b/c I don't want them to get hot.  The coach sticker says to run them at something low, like 50 or 60, but it originally had load range D tires.  Try finding 8R19.5 tires in LR D, good luck!

Quote from: JohnM on August 20, 2018, 07:02 PM
Getting to a 14:1 or 15:1 ratio instead of 'dumping gas' at a 11 or 10:1 http://www.superchevy.com/how-to/engines-drivetrain/0510ch-carburetor-tuning-gas-mileage/ (http://www.superchevy.com/how-to/engines-drivetrain/0510ch-carburetor-tuning-gas-mileage/)


Requires merely a $600 diagnostic tool.


Other than that, parts are cheap.


Anyone handy near Boulder?

I have the innovate MTX-L
https://www.ebay.com/p/Innovate-3918-Mtx-l-Plus-Wideband-O2-AFR-Air-Fuel-Ratio-Gauge-Kit-Bosch-Lsu4-9/2214678600?iid=272697199421&chn=ps (https://www.ebay.com/p/Innovate-3918-Mtx-l-Plus-Wideband-O2-AFR-Air-Fuel-Ratio-Gauge-Kit-Bosch-Lsu4-9/2214678600?iid=272697199421&chn=ps)


$160 and has a gauge..


If I am to ever trust the old carb'd 454 on a very long trip surely I will put the wideband on it.. For reliability reasons..


For one, if you are too rich in mixture not only will you be getting terrible gas mileage and less power (for the same air), but a very rich mixture, especially at long idles, can really decrease the lifespan of your piston rings..


The cylinder walls are supposed to keep a nice oil film on them but you can run too rich to where the gasoline washed the cylinder walls clean constantly and basically it will wear out your rings..


For two, lean can kill your engine.. You could be pulling a big hill and not know how lean you are, and melt pistons, burn valves, get hot, etc..


The 454 will probably run with a wide open throttle at 16:1 and not miss or chug but have crap power and suffer possible engine damage..


If you try to pull a big hill with an engine that isn't running right, that is a good way to blow an engine..


For three, yeah I would want to get good gas mileage so I would want to know what my cruise AFRs are..
If they are too lean then thier is a problem that needs to be fixed, leaner than 15:1..
If it's overly rich then you would just be throwing away gasoline..


I expect a carb to run just on the rich, safe, side, everywhere..


I think a nice 3/8 intake manifold vacuum line to a ball valve for an on-the-fly unmetered vacuum leak would be a good way to lean out your cruise real-time..
If your cruising at 13.5:1 open the valve a crack until you are 14.5-15:1 and cruise away at a nice AFR adjustable to elevation and everything.. Just close it when you go to put down power..
That's your crazy idea for the day..




Do you just trust your carb? I don't.. For all I know it's just good enough to make me think it runs fine but in secret it is conspiring to blow up my engine if I ever need to floor it for more than a few seconds..


I don't think I would trust it without knowing my AFR..


I think a 454 is going to be more resilient to poor AFR than most engines.. It probably isn't going to knock and blow up just due to poor AFR like some engines will, but a poor tune, bad AFRs, decrease the lifespan of your engine in general..


A good tune VS a poor tune could mean the difference between a 75,000 mile 454 life to a 150,000 mile 454 life.. 

Spark plugs to my understanding..


Iridium and other fancy metals are for extended service life..
If you want your plugs to last 50,000 miles, 100,000 miles? or so in your low maintenance grocery getter, iridium is for you.. 
Or if you have one of those vehicles where you have to move the engine to change your plugs, iridium yep..


Good old copper plugs..
They transfer heat the best which is important if you need to resist detonation.
They transfer electricity the best.. They are the best for performance engines..
1,000 LS engines and 500HP honda engines will be running copper plugs..
Racers will be running copper plugs..
But they last something like 10k-20k miles.. Less than iridium, but iridium electrodes will glow red hot and cause detonation in at-the-limit applications.. The hard tips sometimes break off and destroy cylinder walls, scratch it all to heck..


Some engines just hate certain plugs.. No real reason..
I tried some split electrode bosh plugs in my M3 and they instantly ruined the idle.. Put the old plugs back in and all was well again..


Spark plug heat range.. Pretty much a balance of how clean your plugs stay VS how cold they stay.. How well they transfer heat from the tip to the head so they don't overheat..


If you don't transfer enough heat out of the end of the spark plug then it will glow red hot and cause detonation/preignition/knock..


If you trasfer too much heat out of the spark plug to the head then it will stay too cold and never get up to a high enough tempature to burn the carbon off of them, and foul out..


It really depends on how hot of a condition you are creating in your cylinder..
If you have just small port heads you aren't getting that much air for that big of an explosion so it's never going to get all that hot.. Maybe a 5 6 or 7 NGK heat range plug?
Put a big valve head on the engine then  your getting more air.. Run boost then you are adding more air.. More air more power more heat.. Probably an NGK 7 for a big valve 454 up to 8s 9s or 10s if you run a turbo or supercharger..


I don't know what they recommend for the 454 stock, am I close?
NGK says YR5 plugs for 1981 P30 7.4.. Heat range 5..
That's a pretty hot running plug for a pretty cold running engine, the right match.. For a hot engine you need a plug that runs colder, sheds more heat..


(https://i.imgur.com/7LBJ6kt.png)

Common knowledge is to run the coldest plug you can without them fouling out..
I'm not sure if/how that applies to a very low tuned engine that needs hot plugs though.. Probably just do what NGK says..


As far as pouring water in the carb to clean out carbon..
I don't doubt a bit that it will work but seems pretty dangerous to hydrolock if you pour too much.. IDK how much is too much..

I would probably atleast try to spray, mist, or steam in into there.. Start small checking your spark plugs and you will know when you have added enough water enough when your spark plugs look brand new..

454 might be able to chug through quite a bit of water.. Boiling water may be better?

I think the cleaning mostly comes from when the water is gassed into steam when the cylinder fires..


I cleaned the carb and put a new gasket and choke on my 454 but I haven't really dug into the BBC specific education yet..
I just like talking engines..

Ok I got the bung welded on the drivers side exhaust and a new AEM Air Fuel Ratio meter is on the way.   Hopefully I'll have some interesting mpg data to report for the 454 after seeing how it's actually running at cruise speed with the stock 750cfm Edelbrock setup .

When it comes tuning with a wide-band tune to the same AFR regardless of fuel type used. The wide band does not know type of fuel ran. Also a 16:1 AFR vs 14:7 is cooler running. So long as you are not under excess load/WOT. No lean cruise tuning with a centrifugal only distributor. You want to run hot? Run the AFR 14:0-15:0 that is where it is the hottest under load/WOT.

Load = Throttle position

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