[cdawzrd]

Not really, depending on the engine. Some engines are built sturdily enough that they can make that power without anything other than bolt-on modifications. For example, the Saab B204L turbo engines make 185 HP stock. Just by changing the mapping in the ECU, you can raise that to 225 or so. Add a new exhaust and intercooler, you're up to 280. Bigger turbo, now you can hit 300-330. Bigger fuel injectors, now you can hit 400. Keep adding more air (bigger turbo) and more fuel (bigger injectors) for as long as the engine can take it. I think the record is currently around 700 HP, which may have been done on an engine with aftermarket pistons, but still, 400HP or more is possible with only bolt-on modifications, no rebuilding of the engine internals.

[justin66]

That's impressive. How many miles would you expect to get out of a B204L motor making 400HP, assuming you were just keeping it on the street?