Are my 454's magnum's??
 

On my boat the stickers say 1988 Sea Ray SRX 7.4 LITER 330.
I know back in the day 454's started at 315 hp so are these magnums? It's my under that most pachanga ' s had magnums. If so...can anyone tell me the difference in the motor's?? Any info is appreciated greatly

No they are standard 454 with cast internals. Mag motors have forged internals and better flowing heads.

So are the mag's all 365 ' s then? And could it really be as simple and throwing some new pistons in and magnum heads on mine to get the power?

I could be wrong, but for some reason I was thinking the Mags are 385 hp.

Buck

Oh see I dont know. Realistically there's not such thing as to much. But there's also no reason to repower a boat with less than 300 hour's on her right

Carbed mags were 365. MPI mags were 385 if I'm not mistaken.

Too change yours to mags you would be pretty much changing everything except the block.

Actually, he would be changing the block too. The mags are 4 bolt blocks.

Well shiot that's not worth it on this boat at this point in time I was searching through the numerous posts about ways to get more hp out of the 330s and it sounds like pistons ported head better intake.

They seem to max around 4450Rpm which I'm told is the right rpm factory for these motors turning 21 pitch cleaver props I can break 60 but I was also wondering...If I ran 23 pitch props...what we'd my rpm drop to probably 4000 or less huh

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.

Please explain I'm sure I don't get it. Why would I want to dump less fuel with I'm gonna assume less of a cam? Wouldn't I lose power then? I'm not sure it just seems like it would?

Alphas must go if you plan any engine upgrades.

I agree alpha drives will not hold up in a heavy boat. Are yours white? The other hold back you have is exhaust on the pachangas

Mine are black were replaced like 90-100 hours ago . What the problem with the exhaust on the pachanga the manifolds or the rest cause I'm pretty sure it's all 5 inch after the risers

Good thing you asked and good thing I thought out loud huh ? LOL.

Bad news for modifications though - but good news you atleast you know what you have and don't waste big $$$.

So what I'm getting is unless I want to repower and find a steal of a deal on bravos it's not really worth it to try with this set up. Maybe I'll just try going up a prop pitch and see if that makes me feel better haha

Lugging the engines puts more stress on the drives. So, really not wise.

If looking for more prop performance see what the others are using for props (Manufacturer, Model, Diameter, Pitch , etc) with success with your same year/make/model/engine/drive equipped boat.

what i was saying in post 19 was you are already flirting with the breaking point with these drives. and more pitch will also stress them more as SB says. i am surprised they put alphas in an 88. i guess they probably had a hard time keeping up with demand for bravos in the first year of production. best way to get a pair of bravos is to shop for parts hulks over the winter. pick them up for a grand, sell trailer for 500, scrap hull for 100 and get another 100 back in aluminum and scrap engine weight. might even find somebody wants the hull for free.

And don't forget that if you do a straight Alpha to Bravo swap, you end up with some new issues. For instance, although your new drives will handle significantly more power, the Bravo gear cases have greater hydrodynamic drag than Alphas. That means you'll need more power to go just as fast (or slow) as you're going now. Then when you add more power, you'll find that the Pachanga hull wasn't built to take much of a pounding anyway. Translation: Sell the Pachanga as is and buy a faster boat.

If you truly have a nice 300 hour boat in good shape enjoy it and save money for gas the boat has an Excellent hull and handles Great in rough water. The boat has alpha drives because the bravo came out in 1989. Last these boats like mirage plus props. Contact Brett at a blades you can prob pick up a couple mph by changing props