* Year of manufacture: Engine technology and designs changed over the years. A 350 from the 1960s will have very different horsepower than one from the 1990s or 2000s.
* Modifications: Aftermarket parts (camshafts, carburetors, intake manifolds, exhaust systems, etc.) significantly impact horsepower. A stock engine will produce less horsepower than a highly modified one.
* Application: The intended use (truck, car, boat) affects the engine's design and therefore its horsepower output.
Therefore, you can't determine the horsepower without more specific information about the engine in question. You'd need to know the year, make, model of the vehicle it's in, and whether it's been modified.
