* Year of manufacture: Engine technology has improved significantly over the decades. A 350 from the 1960s will have significantly less horsepower than a modern one.
* Manufacturer: Different manufacturers (Chevrolet, Ford, etc.) tuned their 350s differently, resulting in varied power outputs.
* Modifications: Aftermarket parts like camshafts, carburetors, intake manifolds, and exhaust systems can dramatically alter horsepower. A stock 350 will have less horsepower than a highly modified one.
A stock 350 from the late 1960s might produce around 250-300 horsepower, while a modern crate engine (a new, pre-assembled engine) could easily exceed 400 horsepower. Highly modified 350s can produce far more.
