SAE gross horsepower definition
A production engine's actual power available at the flywheel or output shaft (usually crankshaft ) as tested with an absorption dynamometer . It differs from SAE net horsepower in that many of the accessories (such as alternator , water pump , etc.) are not attached. Engines before 1973 were primarily measured with these "gross" numbers. Since 1973, "net" figures were published. This confusion caused many people to suppose that their engine had been seriously de-tuned when they saw that the same engine in 1972 had 400 hp but in 1973 had only 235 hp. (This example is from the Cadillac 500 cubic inch engine). Compare SAE net horsepower . Also see brake horsepower and horsepower .