Gas Mileage: 454

[RayCameron]

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.

[89Elanden]

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   

[ClydesdaleKevin]

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

[Oz]

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.

[tiinytina]

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

[RayCameron]

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.

[ClydesdaleKevin]

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

[tiinytina]

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

[Froggy1936]

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

[jimbo16720]

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

[HandyDan]

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!

[tiinytina]

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!!!! 

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

[ClydesdaleKevin]

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

[DonD]

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!

[ClydesdaleKevin]

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

[DonD]

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.

[DonD]

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!! 

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

[jackd40]

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.

[Oz]

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

[DonD]

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!! 

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.

[ClydesdaleKevin]

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

[gary19734]

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

[ClydesdaleKevin]

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

[gary19734]

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

[ClydesdaleKevin]

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