Diesel more sluggish than gas?
New to the site, so hello to everyone. Will be moving into the motor home world soon. I had pretty much settled on DP or large super C, but I've read several posts here where some folks said some di...
Forum Discussion
I am probably the only one on this forum that has driven THE SAME COACH with both gas and diesel engines. My coach originally had a Chrysler 440 and a Loadflte 3 speed tranny. I upgraded the gas engine from a carb to Edelbrock MPI fuel injection. I upgraded the 3 tranny to a 4 spd Allison 545. My "off the line" improved greatly as the technology advanced the basic engines performance and the lower first gear got it to the wheels.
But I wanted more! So I removed the 440 and put in a Duramax 6.6L turbo diesel with a 6 speed Allison. The first 4 gears in the 6 spd are the same as the 4 gears in 545.
So what was the difference? With the gas engine when I switched trannys with the better gearing at the lower end, it leaped off the line much better than with the 3 spd (2nd and 3rd were the same as 3rd and 4th). Now since a diesel has its power at lower rpm, I needed those other two gears to keep my rpms down at highway speeds.
Bottom line, for the first 30 ft the improved gas engine MAY have beat the diesel engine (primarily due to turbo lag), but beyond that the diesel runs away from what the SAME coach did with the "improved" gas engine.
An added bonus is because the coach stayed the same length and almost the same weight, I have a good fuel mileage comparison when everything else stays the same. The difference: with gas I got 7.5 mpg on average, with diesel over 25,000 miles I have gotten 14.2 mpg.
And its more fun to drive!
But I wanted more! So I removed the 440 and put in a Duramax 6.6L turbo diesel with a 6 speed Allison. The first 4 gears in the 6 spd are the same as the 4 gears in 545.
So what was the difference? With the gas engine when I switched trannys with the better gearing at the lower end, it leaped off the line much better than with the 3 spd (2nd and 3rd were the same as 3rd and 4th). Now since a diesel has its power at lower rpm, I needed those other two gears to keep my rpms down at highway speeds.
Bottom line, for the first 30 ft the improved gas engine MAY have beat the diesel engine (primarily due to turbo lag), but beyond that the diesel runs away from what the SAME coach did with the "improved" gas engine.
An added bonus is because the coach stayed the same length and almost the same weight, I have a good fuel mileage comparison when everything else stays the same. The difference: with gas I got 7.5 mpg on average, with diesel over 25,000 miles I have gotten 14.2 mpg.
And its more fun to drive!
