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Are my 454's magnum's??

Old 08-28-2014, 09:21 PM
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Default 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
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Old 08-28-2014, 09:25 PM
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No they are standard 454 with cast internals. Mag motors have forged internals and better flowing heads.
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Old 08-28-2014, 09:28 PM
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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?

Last edited by slowmo32; 08-28-2014 at 09:31 PM.
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Old 08-28-2014, 09:41 PM
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I could be wrong, but for some reason I was thinking the Mags are 385 hp.

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Old 08-28-2014, 09:51 PM
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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
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Old 08-28-2014, 09:52 PM
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Carbed mags were 365. MPI mags were 385 if I'm not mistaken.
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Old 08-28-2014, 10:02 PM
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Originally Posted by slowmo32
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?
Too change yours to mags you would be pretty much changing everything except the block.
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Old 08-28-2014, 10:06 PM
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Actually, he would be changing the block too. The mags are 4 bolt blocks.
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Old 08-28-2014, 10:47 PM
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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.
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Old 08-28-2014, 10:52 PM
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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
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