How to Calculate a Harley's Horsepower

Harley-Davidson engines are known to be the "Kings of Torque".

Horsepower is the work produced that maintains movement. One horsepower is defined as producing 33,000 foot-pounds of work in one minute. An engine can continue to make more horsepower as long as RPM is increasing faster than torque is falling. Torque and horsepower are the result of frictional losses, volumetric efficiency, engine displacement, BMEP (Brake Mean Effective Pressure) limitations and RPM. As RPM rises, there is less time to fill the cylinder and torque begins to fall off. When torque is measured over time, it becomes horsepower. If you know the horsepower you can calculate the torque.

Difficulty:

Easy

Instructions

Things You'll Need

• Calculator

1. • 1

     Multiply torque by RPM.

   • 2

     Divide your answer by 5252. For example, a TC88 engine produces 84 foot-pounds of torque at 3,500 RPM. The horsepower would be 55.97.

   • 3

     Multiply horsepower by 5252.

   • 4

     Divide answer by RPM. Example: A TC88 engine records a maximum of 78 horsepower at 5,500 RPM. The engine torque would be 74.48.