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thinking about LS swap from twin 454???

Old 10-27-2018, 09:28 PM
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Does anyone make an affordable LS exhaust manifold yet?
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Old 10-27-2018, 09:48 PM
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I’m dying to see a 650+ 454 cu in engine live in a boat. There is someone in the swap shop and on Facebook selling a pair of LS marine engines. Think they were in a sunny. Might be a good person to talk too

here it is

416ci LS3 motors 25k

Last edited by Crude Intentions; 10-28-2018 at 12:28 AM. Reason: Wrong number
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Old 10-27-2018, 10:15 PM
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Originally Posted by Crude Intentions
I’m dying to see a 600+ 454 cu in engine live in a boat.

416ci LS3 motors 25k

I ran 600HP 454's for 6 yrs with no issues.(cruise@4800 RPM, 6500RPM@WFO) I then detuned them to ~550-575Hp for another 5 yrs. Fully refreshed them this summer and I run 87 octane.

416ci LS3 motors 25k

And Dennis's engines are a good package.

Last edited by Rookie; 10-27-2018 at 10:22 PM.
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Old 10-27-2018, 10:22 PM
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Interesting. N/A? I mean naturally superchargers would live. If N/A please share the specs and do tell what exhaust you ran. Also I will correct but I meant to say 650+.
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Old 10-27-2018, 11:37 PM
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Originally Posted by Alwhite00
Does anyone make an affordable LS exhaust manifold yet?
I mentioned KEM's many times many years ago. They where like $700-800 back then, Sure they are more than 1k now,but have not checked in a few years. Give'm a call.
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Old 10-27-2018, 11:47 PM
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Originally Posted by XtremeCFM
Hey guys, i have a scarab panther 30' that i have the twin 454ci motors out of it, i was going to build them up NA to make about 680ish hp.
Originally Posted by XtremeCFM
combo would be basically 11:1, hyd roller cam (thinking something in the 234/242ish), aftermarket alum heads (ported), leaning towards dual plane intake with hp950 carb and dry exhaust should do it
You think or know that combo will make that hp ? Any sheets of yours (not Chris/Scott/or Mark's) if you have done this ?
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Old 10-28-2018, 01:38 PM
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680 is a stout number for a NA 454/468. Your asking for almost 1.5hp per cubic inch. I doubt that setup will be very user friendly.

Most marine high performance endurance builds, are usually in the 1.0-1.2hp per ci range. I certainly dont see 680hp with that cam, dual plane intake, and marine exhaust manifolds. At least not on a dyno thats actually calibrated.
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Old 10-28-2018, 01:46 PM
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Originally Posted by MILD THUNDER
680 is a stout number for a NA 454/468. Your asking for almost 1.5hp per cubic inch. I doubt that setup will be very user friendly.

Most marine high performance endurance builds, are usually in the 1.0-1.2hp per ci range. I certainly dont see 680hp with that cam, dual plane intake, and marine exhaust manifolds. At least not on a dyno thats actually calibrated.
you just have to use the right correction factor and they make all you want.
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Old 10-28-2018, 02:55 PM
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Originally Posted by compedgemarine
you just have to use the right correction factor and they make all you want.

that seems the way to do it here. Awesome power claims but boat is no faster than another one with a 500efi. Of course they have all the excuses in the world as to why it isn’t as fast. Lol.
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Old 10-28-2018, 04:23 PM
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After doing the 600HP to now ~550-575HP my boat is faster with less HP. I believe this is because I brought my pk TQ and HP down and closer together. I couldn't believe how far the splits would be on a 680HP 454. When cam testing in the race boat the highest HP dyno "King" camshaft wasn't always the best or fastest in the real world boat.
Oh, and my 454's are so far 4mph faster than the 500efi's that were original to my boat.
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