To give an example as in the 80's there was no big block EFI / MPI engines as they did not come into play starting 1993. Anyways all carb 454 HO MAGs were 350 hp and all 454 Mags MPI were 385 hp. This is for model year 1992 thru 1996 for the carb HO MAG and 1993 thru 2000 year models for the 454 MPI MAG.

All carb just plain jane 454 were 300 hp from 1991 to 1996 and the plain jane 454 MPI was 310 and some 330 hp thru out the 90's. In the 80's Mercruiser had different hp for the 454's thru out and again no fuel injection big blocks in the 80's nor 1990, 1991 1992, I'll post the different hp for the 454 in the mid to late 80s when I double check the ratings.

OEM Mercruiser and Volvo dealer -

Never could figure out the deviation on the base 454 carb hp ratings some had webers some had quadrajets some had tbi injection just like the 220 horse pick up version ,believe every one was peanut port ,always wanted to throw a set of 049's with a performer and holly on one just to see . Still might , have a 22 stingray coming in and its a 88-bravo one combo , thru hull exhaust too .New set of head gaskets would practically be scheduled maint on a boat like this anyway lol

in the 80's you had the 7.4L Carb engines. Those were 330HP rated. Then in 1988 came the 454 Magnum carb. Rated at 365HP. Then the MPI engines came out. The 1996 and later 7.4 MPI was 310HP rated. 454 MAG was 385HP rated.

To the original poster, you have a 330HP 454 with cast internals, peanut port iron heads, and low compression.

Weren't the 330HP 454's in front of Alpha's (just a few year run) called Magnum's too ? Or some weird schit like that ?

Yes, I think that was in 1987.

Yeah that's what they're on my pachanga and I could swear they were called magnums that's what started this

Whoops wrong thread

Sweet thanks for the bad news haha. So...Low compression huh? So why don't I slap a turbo on each of them and keep it down to like 5lbs of boost has anyone ever tried that?? With some new head studs and gaskets it might just hold up?

you can do a lot with a 330 hp 454. 450 hp with cast internals is possible and will hold up a LOT longer than those alphas. the best thing you can do with big block-alpha is 2 barrell carbs and economizer cams...

Back in the 80s i think the twin galebanks turboed 475 horse Mecruised was started as just a 330. Could be wrong though . Never here anything about the old 475 turbos good bad or otherwise here.