The Jargon Patrol: Every review or article on automotive issues refers to it, yet the average motorist cannot equate horses with their turbocharged speedster or under-performing banger.
Despite the seemingly natural equation, relating to equine measurements, horsepower is actually a mathematical measurement, linked to the torque, or pulling power of the engine.
In mathematical terms one unit of horsepower is equivalent to the ability to lift 33,000 pounds in one minute. Converting it into other units, 1 horsepower is equivalent to 746 watts per hour. Unfortunately, due to variations on definitions of the size, weight, mass, and so on, the figure is only a rough guide.
All sides agree on what a Watt is, but there is no agreement on hp. In the US 1 hp is 745.6999 Watts. One metric horsepower is 735.499 Watts, while one horsepower in British measurement is 745.7 Watts.
In any event, to measure lift, the torque produced by the engine is measured. The device most commonly used is a dynamometer, essentially a brake - hence the term brake horse power (bhp). High horsepower (or bhp) is an indication of high performance.