AMS, Google search "SAE hp ratings". Summerized below from Wikipidedia:
Prior to the 1972 model year, SAE gross hp
American automakers rated their engines in brake horsepower (bhp), frequently referred to as SAE gross horsepower, per SAE standards J245 and J1995. SAE gross hp was measured using a stock test engine, generally running with few belt-driven accessories and sometimes fitted with long tube (test headers) in lieu of the OEM exhaust manifolds.
1972 - 2004 SAE net horsepower
Automakers began to quote power in terms of SAE net horsepower in accord with SAE standard J1349. Like SAE gross and other brake horsepower protocols, SAE Net hp is measured at the engine's crankshaft, and so does not account for transmission losses. The SAE net hp testing protocol calls for standard production-type belt-driven accessories, air cleaner, emission controls, exhaust system, and other power-consuming accessories.
2005 on, SAE certified hp
In 2005, the SAE introduced a new test protocol for engine horsepower and torque. The new protocol eliminates some of the flexibility in power measurement, and requires an independent observer present when engines are measured. The test is voluntary, but engines completing it can be advertised as SAE-certified.
