* Horsepower (hp): This is a measure of an engine's *theoretical* power output. It's a calculated value based on the engine's design and specifications, often determined from formulas or estimates. It doesn't account for power losses within the engine itself (like friction).
* Brake horsepower (bhp): This measures the *actual* power delivered by the engine's crankshaft. It's measured using a dynamometer (also known as a "dyno"), a device that puts a load on the engine and measures the torque and rotational speed. The bhp accounts for all power losses *inside* the engine – friction, internal resistance etc. It's the power available *at the crankshaft* to drive the rest of the vehicle or machinery.
In short: Horsepower is a theoretical maximum; brake horsepower is the real-world power available at the crankshaft. Bhp will always be lower than the rated horsepower.
