Engine specs can be confusing. A review may describe an engine as "packing 400 pounds of torque" or "making 350 pound-feet of torque," and this will mean nothing to you if you're used to working with horsepower. Learn to convert between units so you can actually understand what you're dealing with and compare engines meaningfully.
Find your torque. Torque measures the ability of a force to rotate a body. The standard torque unit is the newton-meter (Nm), but if your specs mention "pounds," it lists engine torque using the imperial unit of pound-force-feet. It may refer to the unit as "pound-feet," "pounds-foot," "pounds-feet" or some similar combination of the words. Some reviews even refer to the unit as "pounds," even though pounds actually measure mass or force.
Find your engine speed. Specs uniformly measure engine speed in rotations-per-minute, or RPM.
Calculate power. Multiply torque and engine speed to calculate power. For instance, if your engine gives 350 pound-force-feet of torque at 4,000 rotations-per-minute, you will get 1,400,000.
Convert to horsepower. Multiplying torque and engine speed gives you power in a unit no one ever uses. Divide this answer by 5,252 to convert it to horsepower. Thus, 1,400,000 pound-feet-per-second is about 267 horsepower.
