Why all the hype about horse power and torque?

[i82much]

Originally Posted by 1972RedNeck

This is almost as good what brand of oil is best.

When it comes to horsepower and torque measurements, one is no good without the other.

Technically, power tells us the rate at which work is done. As a consequence, we can calculate the acceleration of a given load knowing only the horsepower without knowing the torque. It does not matter whether we have 200 ft lbs of torque at 1000 RPM or 100 ft lbs of torque at 200 RPM, we simply change the gear ratio and the load accelerates at the same rate.

Practically speaking, knowing both the peak power and the peak torque and the respective RPMs at which they occur gives us a good bit of insight into how much average power the engine makes across a range of engine speeds. This sometimes results in some real confusion over what the word "torque" really means.

If we could have an infinitely variable CVT, we could always accelerate a load fastest by using the engine with the highest peak horsepower we could find and running that engine at that RPM. Engine torque would quite literally be irrelevant. Since we can't do that in practice, we manipulate gearing the best we can to suit the output characteristics of the engine we have, and it is very helpful to have an engine that produces a broad power curve which, when we rate the engine for peak power and torque, will show good low RPM torque numbers and good high RPM power numbers.