Horsepower does motor 455 Oldsmobile have?

Answer 1

Varies depending on year engine was built, as well as compression ratio. The most powerful factory 455 was installed in the 1970 Toronado (W30?) and is quite rare--that engine is rated at 400 hp--455 Olds engines installed in vehicles with the Police Apprehender Pursuit package (exceedingly rare) were rated at 390 hp--Be advised that these engines were all produced prior to 1972 when compression ratios dropped, and were rated at the flywheel. 1972 and later engines were "SAE net" hp--measured at rear of transmission with ALL accessories (Power Steering, alternator, A/C operating.
These engines excelled at torque output rather than horsepower due to their undersquare bore and stroke configuration--that is--their stroke is longer then their bore.