What was the horsepower output of the 1965 Shelby GT350?

The 1965 Shelby GT350 produced 306 hp from its modified 289-cubic-inch V8.

Ford asked Carroll Shelby to turn the Mustang into a competition-capable sports car for SCCA B-Production racing. Shelby American strengthened the suspension, upgraded the brakes, added headers and a high-rise intake manifold, and fitted a larger Holley four-barrel carburetor. These changes raised the engine’s advertised output from the Mustang’s 271 hp to 306 hp.

The 1965 GT350 was a lightweight fastback rather than a luxury grand tourer. It had no rear seat, a four-speed manual transmission, distinctive blue stripes, and a production run of only 562 cars, including racing versions. That limited output is part of its appeal today.

A common mix-up is confusing the street GT350 with the GT350R competition model. Racing versions could be tuned for substantially more power, while later Shelby models used different engines and ratings. The 306-hp figure is the canonical factory rating for the 1965 road-going GT350.