masterplumber said:Man, your just feeding the fire over here, with me wanting to build a medium duty. Besides the cool factor, you have excess capacity and get a mile or 2 to the gallon better mileage. Do you think it will improve when you go to a manual trans? Do you have any experience with the DT466 or the bigger Cummins motors, as far as mileage? I'm just wondering what the perfect drivetrain combo would be, as far as power vs efficiency. I imagine my theoretical vehicle would weigh about what yours does, but I also need to be able to tow up to an additional 12,000 lbs and I travel through the Rocky Mountains a lot.
The manual gear box will have an overdriven, where as this tranny is a 1:1 in high gear. The tranny I am considering is a 0.74:1. If I had it to do again, I would have gone for the 466. They are great engines, lots of power, easy to work on, and parts are everywhere. It would use more fuel (8 to 10 mpg is what my buddies box truck with a 466e gets). I will have to get a bigger turbo and a set of bigger injectors to get up to stock 466 power. I am not power hungry, just a few more ponies would be nice at times. I will be adding a water/meth injection to keep it cool on long climbs and hard towing. For now I think the tranny is my major concern. Then I will start other modifications to make it just right.