The 1971 Ford Mustang Boss 351 was rated at 330 hp.
Its power came from Ford’s high-output 351 Cleveland V8, identified by the R-code engine designation. The 351C used four-barrel induction, solid lifters, high-compression forged pistons, four-bolt main caps, and Ram Air, making it the most powerful small-block Mustang engine of its year.
The horsepower figure reflects the SAE gross rating system used in the early 1970s, measured under less restrictive test conditions than the later SAE net system. That is why modern comparisons can show lower numbers without indicating a different engine.
Ford built the Boss 351 for the 1971 model year only, producing 1,806 examples. It is sometimes confused with the Boss 302 or the optional 429 Cobra Jet, but 330 hp specifically identifies the Boss 351’s advertised output.