Engine/Transmission (1998.5 - 2002) HP/Torque Differ with rear end ratio?

[Dkevdog]

Ok I've got an interesting question. Picture two identical trucks, with mods they way you'd like them. The only difference being the rear end gear ratio. If you dynoed both trucks would there be a difference in HP/Torque between a 3:55 and 4:10 setup? If so or if not, then why?



Kev

 

[DavidC]

The only difference is that the hp and torque would be at different rpm levels if measured at the rear wheels.



Dave

 

[Loren]

The 4. 10 differential will produce more torque at the wheel than a 3. 54 differential for the same torque produced at the engine. This is because you are running in a lower gear with the 4. 10. It is essentially the same thing as selecting 4th gear instead of 5th, for example. You will get more torque but lower RPM.



The horsepower will be equal with each differential. This is because the higher torque produced by the 4. 10 differential is offset exactly by the lower RPM at the wheel. Power equals torque multiplied by rotational speed. The torque is higher (at the wheel) because of the lower gear, but the rotational speed (at the wheel) is lower for the same reason.



Loren