Think of pushing a car, torque is the force you apply to the car and rpm is the foot steps you take to move that car
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Both are needed linked and just as important as one another.
What I'm trying to get through is, a dyno cannot measure HP. PERIOD. End of discussion. It MUST have a torque spec in order to "figure" HP. Torque is the DIRECT measurement and THEN the dyno "figures" HP based on torque.
Now, if you're talking about a horse pulling weight X amount of distance then that's a horse of a different color. That IS a direct measurement of HP, but a dyno cannot do THAT. It MUST see torque FIRST.