Gross Horsepower is defined as the amount of power generated prior to the loss from auxiliary systems.

• A. the usable horsepower after losses
• B. the amount of power generated prior to the loss from auxiliary systems
• C. the horsepower at the wheels
• D. the horsepower rating at rated speed

Answer: (B)

Gross horsepower is the engine’s power at the crankshaft before any parasitic losses from auxiliary systems are subtracted. The statement you’re evaluating matches that idea exactly: it describes the raw output generated prior to losses from things like the water pump, alternator, and other accessories. The power you actually use is after those losses (net horsepower). Power at the wheels is brake horsepower, which includes drivetrain losses, and the horsepower rating at rated speed refers to output at a specific RPM, not to parasitic losses.