Defining Torque and Horsepower

Let’s start with some definitions. Torque is the twisting force produced at the heart of the engine, its crankshaft. Torque is measured in pounds-feet. One pound-foot is equal to the twisting force produced when a one-pound force is applied to the end of a one-foot-long lever.

For example, if you placed a wrench on a horizontal bolt and exerted one pound of pressure on the handle one foot from the center of the bolt, you would produce one pound-foot of torque, or twisting force.

The key word here is force; torque is a measure of an engine’s ability to apply twisting force to the vehicle’s crankshaft.

Horsepower (HP) is a general expression of an engine’s ability to do work, expressed as a rate. Horsepower is calculated using factors of force, time and distance. The key word here is power. One horsepower is equal to the amount of power it would take to lift 550 pounds one foot in one second.
The phrase horsepower came into use in the late 18th century, when steam engines started doing work previously performed by horses, and potential steam engine buyers needed an easy comparison to understand a machine’s capabilities. Although we’re a long way from comparing horses to automobiles, horsepower’s scientific definition continues to be the standard for defining an engine’s power.

In vehicle specifications, the torque and horsepower ratings are usually followed by the @ symbol and a number indicating the engine’s revolutions per minute (RPM). For example, in its specifications,the Nissan Titan has 305 HP @ 4900 RPM and has 379 lb-ft of torque @ 3,600 RPM
Just so you know the difference