Well if you read all the ads for performance parts and add up all the claims you can easily come up with 300+ horsepower. They do it all the time in the magazines, right?
But the reality for a stock 250 in good condition internally goes more like this..... original 155hp, a better intake and the right carb or carbs along with a better exhaust system, good street cam, and a decent and accurate ignition system should bring it to about 200hp at the flywheel. That's about the end of the story for parts that just sort of bolt on.
The big horsepower maker is in the cylinder head and compression ratio. This requires going inside the engine and doing what it takes to build compression and get the head flowing well. The big money gets spent on the head but the end result should bring you to a very realistic 250 - 270 hp at the flywheel on a street driven 250 with pump gas and no steroids ( Nox ).
The key to all of this is to plan it all from the start and select both parts and machine work that all works together. Bolting on a drag only intake manifold and carb to an otherwise stock engine and exhaust won't do much in terms of added horsepower or driveability.
Mike G
