Thread: 350 Winnie 20' 1981 motor home

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the cummings 94-98 is th most powerful of the 12 valve non electronic engines It would be a good combo but a job to put in. Might be pretty loud inside you probably will have to do something with rear gearing
I have a 76 18 ft m/h with a stock 454 400 combo i get about 10 mpg when hauling my 18 ft trailer and car 55 mph max. can always want more power but works ok. they are a brick with wheels

Heres a suggestion keep it simple pull the 350 stroke it as big as you can go , vortec heads good towing torque cam headers etc . maybe an extra 100 hp out of your original if your lucky dont have to change any gears or anything else keep it cool and run good oil and it should go a long time. a cummings or built big block it wont be but it should do the job. My preference would be a hd 5 spd manual but not practical in a m/h.
just my 2 cents and suggestion

I have a 2000 37 foot motor home with a 320hp turbo cat and a allison 6 speed transmission..rig is about 25,000 pounds and get consistent 11 mpg pulling a car trailer with a 5,000 pound truck on it, turning less than 2,000 rpm.

I think for longevity you could use a diesel and get the best possible fuel mileage and reliability.

I would use the one that fit the best, there are many good diesel engines out there.

The simplest and cheapest would be to build that 350 for low end torque,calculate rpms at drive speed and match that to the largest torque numbers you can at that rpm....no reason to have it do much past the rpm you will be cruisin at anyway...when you hit a hill it will slow down and down shift anyway.

I dont see why you could not get very close to 400ftlbs out of that engine and that would be plenty....

Any gas engine will get less mileage than diesel, but between the more expensive fuel and the greatly increased cost of a diesel engine.....

It`s a hard choice.........for about 2,000 bucks you should be able to get 50,000 trouble free miles out of the gas one....or more miles....since you have a good running base to start with anyway.

I would not worry about the rpms much.......my 460 with 4.11s and a c-6 went 250,000 miles with no problem and at 65 was at about 3,200 to 3,300 rpm all the time and at about 9 to 10 mpg no matter what.


From my experiance driving a huge motor home and now having more than enuff power 1,000 ftlbs or so ...I can honestly say it really only comes into play on the long steep grades and then I just mostly slow down to 45 with the big rigs and take it easy to prolong the engine anyway.

On the flats, guys with the same size or bigger motor homes and the gas engines...454,460,v10s etc maintain the same speed or pass me.....I usually keep her at 70 or less even when the speed limit is 75...even though it has no problem at all going way way faster than that...

I am sure your rig would do fine with a 350/383 towing build.....no wheel stands or passing everything on the road going up a steep grade, but will still be just fine in a 20 footer with a trailer behind it and be the cheapest easiest option..the 383 being more expensive of course than a 2,000 dollar tow build on the 350.......

Hope this helps some in making your descision......