The previous owner blew the original engine and swapped it for a reman. '95 corvette LT1. my question is: is there truly a difference in power between the f and y-body LT1's? I know the y-body LT1 is rated at 300/335 as opposed to 285/32X. If it's the same engine designation, is the f-body simply underrated?

 

Engines are rated by the factory based on the specific configuration when installed in the car, including intake, exhaust and standard accessories. The Corvette had a cleaner intake system, and dual exhaust. Basically, its the same engine with a different accessory bracket on the front. Minor differences like dual knock sensors in the Corvette, 4-bolt mains, oil pressure switch interlinked to fuel pump, etc. - but nothing that affects HP. The 93-95 F-Body LT1 was rated at 275HP. 96-97 was 285HP, supposedly due to the dual cats. I suspect GM may have understated the rating on the F-Body LT1 down a bit, to avoid making it look like a better deal than the Corvette.

 

The Corvette engines also had a better exhaust manifold, which was basically a small tube shorty header. Not a cast manifold like the F-cars had.