Motorhome Gas Engines

Tools Josep Ma. Rosell

July 26, 2012
Filed under RV Tech Q&A

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I am looking for an impartial opinion from neither a Ford nor a GM/ Workhorse fan. I am considering buying a used 2005 or newer motorhome and would like an honest opinion about which engine is better on both flat and mountainous terrain (Ford 6.8-L or GM 8.1-L). I don’t think the Ford has enough torque for the mountains.

Mike Mathis | Via email 

Anytime we have a GM versus Ford question, we’re bound to get a lot of comments, but here it goes. High torque at low rpm is helpful for getting a heavy load moving away from a stop. With an engine, you can’t have torque without rpm, and you can’t have horsepower without torque. However, horsepower is the unit of work that can best be used for comparison for hill-climb speed capability. Horsepower (hp) is a measure of work over time: hp = torque x rpm/5252. The 2005 Ford F-Series Super Duty 30-valve SOHC V-10 is rated 362 hp at 4,750 rpm and 457 lb-ft of torque at 3,250 rpm. The 2005 Vortec 8100 V-8 16-valve pushrod engine is rated 330 hp at 4,200 rpm and 450 lb-ft of torque at 3,200 rpm.

Both engines are fairly close in specs, but the Ford’s three-valve-per-cylinder SOHC design is a little more rev happy, while the pushrod two-valve-per-cylinder Vortec reaches its peaks at lower rpm. Assuming that two engines are pulling the exact same loads, and their gearing is ideal for the task, the engine with more true hp (not brochure hp) will get you up the mountain faster. But in real-world comparisons, the engines don’t always have gearing perfect for operating conditions, and there are other factors like fuel mileage, engine sound in the cab and engine feel to the driver. Therefore, I suggest you test drive motorhomes with both engines and decide for yourself which one you prefer.

– Ken Freund


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5 Responses to “Motorhome Gas Engines”

  1. Steve Rubelmann on July 26th, 2012 4:49 pm

    I will stick with my Chevy (GM) 5.7L in a class B. It is the second GM built motorhome I have owned and have had no problems with it. It seems whenever I hear of a catastrophic engine failure in a gas engine it is a Ford product. I know my 5.7L won’t run up a mountain like the old 460 or a current V10, but it consistently give far better fuel mileage and little or no problems. I’m not trying to be first up the hill anyway.

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  2. Bill Forbes on July 26th, 2012 7:45 pm

    We had a Ford chasis (97 Cruisemaste with the 460 V-8) for several years, until we started carrying too much “stuff” and moved up to a diesal. No complaints about the Ford, although we did warp an exhaust manifold. But the other two things to consider are how much you can tow and how fast you can stop. When we were shopping, we noticed many of the Chevy engine chasis had a CVWR only a few hundred pounds above the GVWR, which means you can’t tow much. The Ford chasis generally had at least 5,000 pounds difference to allow towing a reasonable sized car or trailer without unloading everything from the motorhome. We also saw a lot of letter to RV sites about Chevy engines overheating. Just saying -

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  3. Wallace Twigg on July 30th, 2012 8:11 pm

    The tie breaker is the Allison transmission which is paired with the 8.1 on the Workhorse Chassis. My opinion..

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  4. Doug Holmes on August 8th, 2012 1:05 pm

    I have owned two coaches with Chevy engines. One with the 454 another with the 8.1 and the Allison transmission. I have no complaints both were excellant engines. I put over 80,000 miles on the 454 with no issues. I have friends who have owned Ford engines. Half of them praise the engine, the other half curse it and have had horrible issues.

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  5. frank kasper on August 16th, 2012 10:39 am

    Hi
    I do run the 460 Ford in the Class C and found the issues with the exhaust manifolds warping. After repairing the manifolds (resurface and install larger maniflod studs and bolts that hold the manifold to head), I now let the engine idle at about 1000 rpm for 2 or 3 minutes before shutdown. This allows the engine and manifolds to gradually cool down which has prevented the dreaded warpage and exhaust leaks.
    My coach has just over 120,000 miles on it and still runs like a trooper!

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