Chevy Duramax Turbo Diesel

At the risk of opening the floodgates of previous discussions, let me add a few points on torque and horsepower. There have been many posts on this subject here and on most other RV forums. There is a perception that torque is more important than horsepower. This may be true if the only objective is to move the camper from stopped. Torque is a measure of force  available. For any given engine torque, the final torque (force) available at the wheels is a function of transmission setting, rear end gearing, and tire diameter. That said, any engine can move any trailer but maybe not very fast. Higher torque is nice, but not the determining function.

Horsepower is the ability to move something against a resistance (like gravity or wind) over time. The heavier the trailer, the steeper the hill, and the higher the speed the more horsepower will be required. It takes a certain amount of horsepower to haul a given trailer up a given hill at a given speed. If you want to maintain 60 MPH on a 6% grade it takes horsepower. If you are satisfied with creeping up the hill less horsepower is required. In both cases the torque requirement is the same.

So, engine horsepower is more important than torque for trailer towing. However, newer, smaller engines develop their horsepower at very high RPMs. I’ve seen some small engines with their horsepower specified at 6000+ RPM. All in an attempt to meet Government mandated fuel efficiency. Not good for reliability and engine life. Given a choice, higher horsepower rated at lower RPMs is better. And if the engine develops a high torque at a lower RPM that’s better too, but not at the expense of ultimate horsepower. Keep in mind: Final wheel torque can be adjusted by gearing. Downshift to a lower gear. The ability to maintain highway speeds against wind and grades is built into the engine at the factory.