approximate horsepower!
#1
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Location: Louisville, KY
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approximate horsepower!
Hey all you engine guru's, I have a question for you. I had my engine rebuilt year before last by a mercruiser master mechanic. It's was a Mark IV 330 HP 454and I upgrade to 461 CI with speedpro coated hyperutectic pistons, Isky flat tappet cam with 230 intake and 236 exhaust @.050 with 515 lift on 110 lobe separation angle. It is topped off with Edelbrock RPM oval port aluminum intake and edelbrock 750 cfm marine carb with GM large oval port heads, (230cc I think) with stock valves. It also has crane roller rocker arms and us still using the stock exhaust straight out the transom. I know it's not a race motor and I don't treat it like that but I was just courious about how much HP it may have if I go to sell it in a year or two.
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Does not matter it will not last long with that cam and stock exhaust. You need aftermarket exhaust with long risers or you will be sucking water back in. You may even need dry exhaust with the 110 LSA.
I just saw you have run it a whole season with that setup. What did the oil look like when you changed it?
I just saw you have run it a whole season with that setup. What did the oil look like when you changed it?
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I'd be surprised if that cam didn't revert water with the stock exhaust. Even if it does not, the stock exhaust will choke down the better flowing intake manifold, cam, and heads you have. No point in putting that combo together then running stock exhaust. That cam is also a bit large for a 461CI with cast internals, like the 330HP has. You really want to keep the rpm 5000 or below, and that cam will probably not make any more power below 5000rpm than one with about 10* less duration. Less cam would probably make more usable power, idle better, and not revert.
I'm guessing here, but with your stock exhaust, and specs you have given, Im gonna say 350-370HP at 5000.
I'm guessing here, but with your stock exhaust, and specs you have given, Im gonna say 350-370HP at 5000.
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I'd be surprised if that cam didn't revert water with the stock exhaust. Even if it does not, the stock exhaust will choke down the better flowing intake manifold, cam, and heads you have. No point in putting that combo together then running stock exhaust. That cam is also a bit large for a 461CI with cast internals, like the 330HP has. You really want to keep the rpm 5000 or below, and that cam will probably not make any more power below 5000rpm than one with about 10* less duration. Less cam would probably make more usable power, idle better, and not revert.
I'm guessing here, but with your stock exhaust, and specs you have given, Im gonna say 350-370HP at 5000.
I'm guessing here, but with your stock exhaust, and specs you have given, Im gonna say 350-370HP at 5000.
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Not suggestion that a "Merc master mechanic" is a bad thing, but reminds me of the guys working at midas, being ASE certified techs. Doesn't necessarily make you a engine builder by being a mechanic.
I went to General Motors training school for 18 months when i was younger. I can still F-up a spark plug swap.
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Dont get me wrong, nothing better than a great sounding cam idling, but nothing worse than a crankcase full of nestle quick!
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I don't think that cam size and duration is a high probability reversion candidate, the LSA is close to it but not quite. I do agree that the engine should make 400-425HP with this combination-EXCEPT FOR THE EXHAUST!-
As others said here, a good breathing power making engine needs to breathe on the exhaust side so invest in a good exhaust upgrade and get the power the engine is capable of making.
Best Regards,
Ray @ Raylar
As others said here, a good breathing power making engine needs to breathe on the exhaust side so invest in a good exhaust upgrade and get the power the engine is capable of making.
Best Regards,
Ray @ Raylar