Gas Mileage: 454

[72-d24]

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.

[Rickf1985]

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.

[tiinytina]

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
   

[Rickf1985]

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.

[circleD]

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.

[tiinytina]

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.   

[Rickf1985]

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.

[eXodus]

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 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.

[tiinytina]

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....

[eXodus]

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

[eXodus]

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:

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

[bluebird]

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.   

[eXodus]

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.

[tiinytina]

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. 

[Rickf1985]

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 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.

[eXodus]

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.

[tiinytina]

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...

[bluebird]

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.

[Rickf1985]

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.

[DaveVA78Chieftain]

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

http://www.quickfueltechnology.com/

Dave

[eXodus]

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 dragcoefficient (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.

[Froggy1936]

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

[bluebird]

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.

[Rickf1985]

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.

[eXodus]

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.