What is the equation that is used to determine break horsepower?

Answer 1

In the English system, one horsepower equals 33,000 foot-pounds of work per minute — that is, the power necessary to lift a total of 33,000 lbs a distance of one foot in one minute.
This value was adopted by James Watt in the late 18th century after experiments with strong dray horses and is actually about 50% more than the rate an average horse can sustain for a working day.
The electrical equivalent of one horsepower is 746 watts in the International System of Units; the heat equivalent is 2,545 BTU per hour. The metric horsepower (see metric system) equals 4,500 kg-m per minute (32,549 foot-pounds per minute), or 0.9863 horsepower.

Answer 2

This is the definition of BrakeHP from wikipedia:

Brake horsepower (bhp) is the measure of an engine's horsepower without the loss in power caused by the gearbox, generator, differential, water pump, and other auxiliary components. Thus the prefix "brake" refers to where the power is measured: at the engine's output shaft, as on an engine dynamometer. The actual horsepower delivered to the driving wheels is less. An engine would have to be retested to obtain a rating in another system. The term "brake" refers to the original use of a band brake to measure torque during the test (which is multiplied by the engine RPM and a scaling constant to give horsepower).

Answer 3

If you knew how to spell the type of horsepower you could look it up.

Answer 4

Gosh, the first yahoo search result for "horsepower" explains it.