How much horsepower does a 1978 454 have?

The horsepower of a 1978 454 Chevrolet engine varied considerably depending on the application (car, truck, marine) and the specific options. There wasn't a single horsepower rating. You'll find ratings ranging from approximately 230 hp to over 270 hp, and even higher in some performance versions. To know the exact horsepower of a specific 1978 454, you'd need to find its original documentation or a vehicle identification number (VIN) decoder that specifies the engine code.