Imagine if you will somebody (me) wondering if we can improve both the performance and mpg of our rig. The Endeavor we used to have was the F53 6.8 V10 with 4spd and I believe weight came in around 25,000lbs and our current rig is 16,400 give or take. We know they are slow because they are moving houses after all but a big part of the problem is drivetrain loss and zero programming from RV companies. I imagine a 460 back in the day had about 220hp, with drivetrain loss knock that down to about 110hp making it to the actual wheels.
😱 I know right? The V10 was perhaps 30 to 40hp better and Godzilla is maybe another 20 or so but probably not as delivered by Ford on the F53. What really gets these behemoths going is TORQUE and it's why diesel pushers, even the low horsepower ones ruled the roads and always will. Even the 260hp ones had 600ftlb and that moves big things easier than 250ftlbs. Some of the mid 2000 and up have 600+hp and 1,800ftlb, I've driven a few, it's like a silky smooth push in the back that just keeps pushing (it's amazing) but the cost is hundreds of thousands.
Can a Class A ever get to that kind of power? Yes, kind of, however in torque the cost would be prohibitive and the engine not very reliable. A turbo would help down low grunt big time (a turbo would be fantastic!!) but it would swallow even more gas, yes, it could get worse than 7 mpg, try 3 or 4. Oy. 😭
So the best we can hope to do is to tune the engine to get some more horsepower and torque, perhaps route cooler air into the intake to help the tune?
Short answer, YES!! Peak HP and TQ are important but in the run up to peak is the most important factors. Over 100ftlb of TQ gained at 2100rpm is something that can be felt! 40hp gain at 2350rpm's is also nice.
Gains are measured at the wheel, Fleetwood claims 362hp so crank hp gain of around 65 plus approx 130lbft gain at the crank = 427hp / 592ftlbs plus the changes in transmission programming meant to be a motor home, not a basic tune from Ford that none of the manufacturers are changing turns the combo into something you can see a meaningful return on investment over a short period of time.
I should have this by tomorrow or Friday in time to test it out myself. I've done this with my previous Mustang's and my 2018 Mustang GT ran a 12.1@116 stock, with a tune it ran 11.7@123 and a gain of 4mpg on the highway when driving nicely.
I doubt I'll see much MPG improvement but drivability improvements should be very noticeable.
Here is a video showing the combo from 5 Star.