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How to Calculate the Torque of a Motor

by Soren Bagley

The torque of a motor is the amount of force that an engine generates. This force is used to rotate a lever arm attached to the engine, which in turn propels the entire vehicle. Torque determines the towing force of a vehicle as well as its rate of acceleration. Torque also has a direct influence on a vehicle's horsepower, since horsepower is simply a measure of how fast the motor's torque is being applied. Torque is measured in pound-feet (lb-ft.)

Step 1

Calculate the length of the motor's lever arm from the data you have. The length should be expressed in feet, which may involve converting the units from meters. If necessary, you can use the conversion calculator provided in the resources section of this article.

Step 2

Calculate the force that the motor is capable of exerting on the lever arm. The force should be expressed in pounds, which may involve converting the units from newtons. If necessary, use the conversion calculator provided in the resources section of this article.

Multiply the length of the motor by the force of the motor. The product of the two numbers is the torque of your motor expressed in pound-feet.

Tip

  • A typical v8 engine has a torque between 240-300 lb-ft.

Items you will need

  • Data on the length of the motor's lever arm
  • Data on the force exerted on the lever arm

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