Improving Fuel economy on a carbureted 454 ?
 

My area of knowledge is British sports cars, I race one vintage.

I have just bought a 1984 Winnebago 22ft Chieftian with a Rochester Quadrajet carbureted 454. It is my tow vehicle for my race car
/trailer. Can I swap out the carb for something modern that will give me more fuel efficiency?

Thanks in advance.

you can swap to a tbi unit (off a stock 454 tbi) but the difference wont be real dramatic and it wont pay for itself. in pickups they generally only see 1-2 increase and most times you can get that with how much you use your right foot

Keeping your foot out of it is the only way to get better mileage. You could go with a 2 gc, but I think your mileage will be better with a quad. I don't know the drive train, but just towing, and the winnie itself, might look at a rear differential change.

they do make Overdrive units that either bolt to the back of your trans or are divorced but im not sure what type or weight rating they could handle

I think gearing is going to be your best.

I personally cannot stand the Quadrejet but
am in no way claiming that a different carburetor will increase your fuel milage,
but if I had a Q-jet carb, I'd put a Holley on
in a New York second. I grew up in the age
of vehicle's that did not have fuel injection
motors, and have rebuilt lots of carbs in my
time. The Carter-Edlebrock is also a good
choice in 4-barrel carbs as well.

not really sure what a Winnebago would be geared at, thinking either 4.56 or 4.10 as most 1 tons are but then if you go to 3.73s (if they fit) then the engine would have to work harder just to get up to speed canceling out the highway mpgs you would be saving and it wouldnt really be much. saying that i would think also hearing is your best bet just not in the read but your transmissions final gear

not saying its going to be the best bet for you but in my 91 v3500 crew cab it came with a 350 tbi 4/80e/205 and 4.10 ratio. i got 12 mpgs with that setup and a year later i got 16 after swapping in a 5.9 cummins and everything else was the same. but dodge paired the cummins up with 3.55s to save on highway mpgs so i could in theory see better mpgs if i change to a lower ratio.

What about bolt on EFI conversions?

efi would be a tbi. (electronic fuel injection) you can find them in chevy trucks 87-96ish and some other applications. after that youre talking about a different block and each cylinder getting its own injector.

the fuel savings vs cost of any swap will end up with the swap not paying for itself unless its a DD. lets say you do increase your mpg up 4 and now you get 12 mpgs and a 20 gal tank will get you 80 more miles per fill up. which will save you 24ish dollars a fill up and if you can keep your conversion under 2k thats still around 100 fill ups which is around 24k miles. now these numbers might be a little high if you can keep the swap down but you have to think about the end game. look at trucks now days that have more efficient and more powerful motors and they are between 14-20 mpgs empty.

i dont see a 454 getting that and even 12 might be pushing it. the main idea imo about motors is the 454 while cruising at 2k rpms has a cfm rating of 233 while a 5.9 cummins (360) only has 177 cfms. so while cruising you still need to have the proper air/fuel mixture to feed that 454 vs feeding the 5.9 or even a 350 of 172. imo if you really want to help your millage you need to keep the cfms low while cruising but keep the Tq numbers hi at low rpms to be able to push the beast. i really wish chevy would put a turbo on most their cars like ford does to help with the mpgs but keep the power when you need it (i.e turbo boost).

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