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Author Topic: Chevy 454 gas mileage experience?  (Read 11449 times)

detectivedrew

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Chevy 454 gas mileage experience?
« on: August 01, 2012, 07:27:04 PM »
I have a 454 hauling a 22ft class a motor home. Engine cooling is fine, new coil, cap and rotor, need to change the plugs. I am averaging about 5mpg which seems a bit low. Can anyone out there with a similar set up let me know what you are averaging.

The last trip was hilly, that probably made a difference.

Thanks
Drew
1984 Winnebago Chieftain 22RC
Chevy 454
Onan 4.0
Malvern, PA

SeilerBird

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Re: Chevy 454 gas mileage experience?
« Reply #1 on: August 01, 2012, 08:12:05 PM »
My last RV was an 27 foot 85 Allegro class A and my current one is a 32 foot 94 Damon class A. I have been full timing in both of them. I get much better than 5 mpg but I can't tell you exactly how many mpg I get because I never fill the tank and check the mileage because I don't really care what my mileage is. 5 seems ridiculously low. I would think you would be getting at least 12 mpg.
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brasstownbald

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Re: Chevy 454 gas mileage experience?
« Reply #2 on: August 01, 2012, 08:58:25 PM »
YES YOUR MILEAGE IS LOW! I own a 1993, 34 foot Allegro Bay, my mileage runs between 7.2 & 8.2 towing a 2000 Saturn and running about 65 miles per hour. Things like how fast you drive, how much weight are you carrying, are you towing & what are you towing, what type of terrain are you driving, all factor into your mileage. You did not mention the year of your rig? Do you have a carburetor or TBI throttle body injection? If you have a carb, when was the last time you had it rebuilt? Changing over to TBI, if your not mechanically inclined might hurt your budget. My old 1984, 27 foot  Allegro had a carb. and I averaged over 8 mpg.

Good luck.
George

mnmnutswer

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Re: Chevy 454 gas mileage experience?
« Reply #3 on: August 01, 2012, 09:02:25 PM »
I have a 1991 38Ft FULL and get 7-9 mpg depending on the hills..........
Terry & Kathy Weller
Direct Sales Jewelry
It goes where you are.

detectivedrew

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Re: Chevy 454 gas mileage experience?
« Reply #4 on: August 01, 2012, 09:05:31 PM »
YES YOUR MILEAGE IS LOW! I own a 1993, 34 foot Allegro Bay, my mileage runs between 7.2 & 8.2 towing a 2000 Saturn and running about 65 miles per hour. Things like how fast you drive, how much weight are you carrying, are you towing & what are you towing, what type of terrain are you driving, all factor into your mileage. You did not mention the year of your rig? Do you have a carburetor or TBI throttle body injection? If you have a carb, when was the last time you had it rebuilt? Changing over to TBI, if your not mechanically inclined might hurt your budget. My old 1984, 27 foot  Allegro had a carb. and I averaged over 8 mpg.

Good luck.

Hi George, it has a 4 barrel carb. I assume the carb was never rebuilt- The year of the rig is 1984 and the engine is an 84. Thanks
Drew
1984 Winnebago Chieftain 22RC
Chevy 454
Onan 4.0
Malvern, PA

Water Dog

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Re: Chevy 454 gas mileage experience?
« Reply #5 on: August 01, 2012, 09:18:08 PM »
I think if the plugs are due for changing, they could significantly affect your mileage. Also, how does your air cleaner look? Our last mh was a 454 26 footer, and it got about 7.5 to 8, but it was fuel injected, so although 5 sounds low, for a carbureted engine, I'm not sure that it's that low.
Dennis

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detectivedrew

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Re: Chevy 454 gas mileage experience?
« Reply #6 on: August 02, 2012, 04:59:45 AM »
I should do the plugs and wires- There previous owner added a high flow K and N and it needs cleaning......
Drew
1984 Winnebago Chieftain 22RC
Chevy 454
Onan 4.0
Malvern, PA

Gary RV Roamer

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Re: Chevy 454 gas mileage experience?
« Reply #7 on: August 02, 2012, 06:47:54 AM »
5 mpg is quite low, but don't expect the 8 mpg that others are quoting either.  A carbureted 454 pushing a heavy load isn't ever going to see 8 mpg. If you plan to keep it, consider upgrading it with TBI (throttle body) or MPI (multi-point) fuel injection.

Meanwhile, try all the basics: plugs, timing, maybe wires too. Have you ever watched the wiring in the dark to see if there is obvious leakage?
Gary
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detectivedrew

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Re: Chevy 454 gas mileage experience?
« Reply #8 on: August 02, 2012, 09:43:07 AM »
Hi Gary,

I never checked the wires. I am going to purchase new wires, plugs, and clean the air filter prior to our next trip- I will provide an update. Thanks again.
Drew
1984 Winnebago Chieftain 22RC
Chevy 454
Onan 4.0
Malvern, PA

Bob Buchanan

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Re: Chevy 454 gas mileage experience?
« Reply #9 on: August 02, 2012, 10:22:12 AM »
Over the past 15 years of RVing I have had a MH with a 454, pulled a TT then a 5thW with a 1/2 ton GMC pickup, a Class C with a ford V10, and now drive a MH w/a ford 460. My mileage on all combos has been 6.5 to 8.5.

Have always been pulling something along the way -- either a toad behind a MH or TT/5thW behind a pickup. Also, being in the West, a day on level will give me better mileage than going over one of our summits. The oldest truck engine I have had was a '94 Winnie Brave w/a 454.
Bob (fulltimer - Rocklin, CA residency)
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ironrat

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Re: Chevy 454 gas mileage experience?
« Reply #10 on: August 02, 2012, 10:41:13 AM »
Fuel mileage can and does vary substantially from one person to another as well as the Terrain you drive in. Some drive with the throttle either push well down or off and nothing in between. Some leave from a stop almost if not on the floor, all this takes a lot of fuel. Be sure all is in good shape and then try driving it as if you have an egg between your foot and the gas pedal and keep top speed down to no more than 60, try it I think you may see an improvement. That being said I do think you are low, my race car hauler being an 79 chevy one ton crew cab with the 454 and a carb pulling a 38foot fifth wheel loaded (heavy) pulls 8.5 to 9 on a regular bases.
Manuel & Denise
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detectivedrew

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Re: Chevy 454 gas mileage experience?
« Reply #11 on: August 02, 2012, 10:45:27 AM »
Thanks, Bob. I am not too far off- My calculations were based on one trip and any statistician would shame me- If I truly want to calculate my MPG I would calculate the median. I would accurately write down MPG for various trips over different terrain. I would need to vary my route times (i.e. traffic vs. non-traffic) for each trip to truly get an accurate number.

I think the plugs and wires will help. 
Drew
1984 Winnebago Chieftain 22RC
Chevy 454
Onan 4.0
Malvern, PA

ChiefM

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Re: Chevy 454 gas mileage experience?
« Reply #12 on: August 02, 2012, 10:45:43 AM »
Run some Seafoam thru it after you change the plugs and wires. That will clean the inside of the Carb. That stuff is amazing.
1986 27RT Winnebago Chieftain

detectivedrew

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Re: Chevy 454 gas mileage experience?
« Reply #13 on: August 02, 2012, 10:47:23 AM »
Fuel mileage can and does vary substantially from one person to another as well as the Terrain you drive in. Some drive with the throttle either push well down or off and nothing in between. Some leave from a stop almost if not on the floor, all this takes a lot of fuel. Be sure all is in good shape and then try driving it as if you have an egg between your foot and the gas pedal and keep top speed down to no more than 60, try it I think you may see an improvement. That being said I do think you are low, my race car hauler being an 79 chevy one ton crew cab with the 454 and a carb pulling a 38foot fifth wheel loaded (heavy) pulls 8.5 to 9 on a regular bases.

Hi, you are correct. I was replying to another post while we were both thinking about physics-
Drew
1984 Winnebago Chieftain 22RC
Chevy 454
Onan 4.0
Malvern, PA

Paul & Ann

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Re: Chevy 454 gas mileage experience?
« Reply #14 on: August 02, 2012, 10:54:43 AM »
One thing to check on the carburetor is the linkage for the secondaries to make sure they are not opening too soon, and also that they are going all the way closed.

Paul

Bob Buchanan

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Re: Chevy 454 gas mileage experience?
« Reply #15 on: August 02, 2012, 01:31:38 PM »
My calculations were based on one trip and any statistician would shame me- If I truly want to calculate my MPG I would calculate the median. I would accurately write down MPG for various trips over different terrain. I would need to vary my route times (i.e. traffic vs. non-traffic) for each trip to truly get an accurate number.

I think the plugs and wires will help.

Most likely that is the case. I recently had mine "really" tuned for the first time and am amazed at how well, and smoothly, this 460 is running now. Will be doing a trip from Sacramento to San Jose in a few weeks and will be doing a close check on the mileage since the tune up -- plus it will be my first test w/o my Jeep in tow.

As to statisticians -- they insist on being wrong 50% of the time. But my favorite stat joke:

A CEO in SF asked his statistician to plan a route to NY that would have the least probability of him being on a plane with a bomb/bomber. After a few hours he came up with a route that had him changing planes 7 times and traveling thru Texas, South Dakota, Florida, and several other states en route to NY.

When asked how reliable it would be, he responded the route will lower the probability a great deal - but, I also want "you" to carry a small bomb in your briefcase. Reason being, the probability of two bombs on the same plane would be close to zero.
Bob (fulltimer - Rocklin, CA residency)
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detectivedrew

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Re: Chevy 454 gas mileage experience?
« Reply #16 on: August 02, 2012, 03:59:48 PM »
Hi Bob,

I love the joke. I am currently working on my thesis- I needed a break from writing.

Drew
Drew
1984 Winnebago Chieftain 22RC
Chevy 454
Onan 4.0
Malvern, PA