HP guestimate on this build..
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HP guestimate on this build..

  1. #1
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    Default HP guestimate on this build..

    Ive got a buddy putting together the following combo. 522CI, Edelbrock 315 RPM rect port heads, 242/248 Hyd Roller 112 lsa 633/633 lift. Bottom end is Lunati blower crank, oliver rods, Dart block 8.0:1 compression. He wants to bolt on a 14-71 Blower shop, with superchiller intercooler, and run 12psi on pump gas. So, question, how much power do you think it will make, and do you think that he can do 12psi on pump gas? He had procharger setup on this engine, at 12psi with the procharger it made 1125hp. He's switching to roots for cosmetic and reliability purposes. Just not sure how much peak power he's gonna lose by going to the roots combo.

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    The duration split on the cam will limit that engine on power. At a given rpm range the engine will start to smother as the cam is not holding the exhaust valve open enough to evac the cylinder head.
    Chris Straub
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    Senior Member EVILFORCE's Avatar
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    Never would have guessed 1100 hp on the previous build.
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    Quote Originally Posted by cstraub View Post
    The duration split on the cam will limit that engine on power. At a given rpm range the engine will start to smother as the cam is not holding the exhaust valve open enough to evac the cylinder head.
    so not enough spread is what your saying chris?

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    Quote Originally Posted by Mild Thunder View Post
    so not enough spread is what your saying chris?
    Those heads make the spread even a little worse than say a set of AFRs with the same intake flow. The Eddy exhaust isn't the most active exhaust port out there due to being in the stock location. Then add in less than excellent exhaust system, as opposed to dry headers and it all adds up.



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    Correct. Your forcing air in so the exhaust valve will need more time to get the exhaust gases out. If not that fresh intake charge will mix with left over exhaust in the cylinder making for an "unpaletable" taste for the engine.
    Chris Straub
    Straub Technologies

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    Quote Originally Posted by gn7 View Post
    Those heads make the spread even a little worse than say a set of AFRs with the same intake flow. The Eddy exhaust isn't the most active exhaust port out there due to being in the stock location. Then add in less than excellent exhaust system, as opposed to dry headers and it all adds up.
    Bingo! ball park this thing will need a 20 degree split I would say.
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    Quote Originally Posted by EVILFORCE View Post
    Never would have guessed 1100 hp on the previous build.
    Regardless what it really made, it will be down 100HP easy from a properly setup centrif motor verses a properly setup roots at the same boost. But it better have a stout drive, because it will make enough power at the hit to blow a Bravo XR off the transom in a heavy boat.

    If that's the cam he ran with the centrif, he may get to the same place with the RIGHT cam under the roots. Where ever "that place" really was. Because as Chris said, that cam was costing him some power, regardless the type of blower.



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    Fantastic info guys. Keep it coming! I was shocked it made that power with those edelbrocks. It was with large dyno headers though. He wants to turn the engines to 6000-6300. We are totally not against getting new cams. He actually has his old cams, which were 252/262 114LSA, but with the low compression, longer duration, with the prochargers, they were lacking some low end out of boost and overall low speed driveability. But, he still has those cams on the shelf, would they work better with the roots setup over his current cams? You guys are right on, as we added more boost to the setup, 14, 15psi, the returns on power output weren't that great. Maybe the boost was just stacking up due to the cam/crappy head flow?

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    8lbs is max for pump gas and a 1471. Even with an inter cooler.

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    Quote Originally Posted by PS&B1 View Post
    8lbs is max for pump gas and a 1471. Even with an inter cooler.
    8 to 1, Intercooled, aluminum heads and a boat? It can go 10 easy. The size of the blower at that boost makes little difference over say a 10-71
    I've ran 12 psi with 8 to 1 using a 8 on a 496 in lighter boat.



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    Last edited by gn7; 11-01-2013 at 08:49 AM.

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    Quote Originally Posted by gn7 View Post
    8 to 1, Intercooled, aluminum heads and a boat? It can go 10 easy. The size of the blower at that boost makes little difference over say a 10-71
    I've ran 12 psi with 8 to 1 using a 8 on a 496 in lighter boat.
    I would probably run a 1071 and lose the inter cooler because its in a boat.
    I also realize you could go to 10 but....... Most boost charts are pretty close wouldn't you agree?
    i know "you" run on the edge...... I just don't know how the OP is wanting to run? Or what boat, size of boat, or even better........ how long is he gonna clamp it for? So going by BDS I said 8 lbs.
    Is it conservative..........

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    I agree a 10-71 would probably be fine for what hes doing. We were thinking the 14 turning slower would net a little cooler setup, plus allow for future builds that might go up in cubic inch. Engines are going in a 42 Fountain with SCX drives. 0-60 times aren't important, boat will spend its life at 3000-6000rpm. I personally would rather see him get some better heads, and lower the boost, but, like everything, budget limited. I'd imagine going to some better flowing heads would net quite a bit of power over those edelbrocks and their poor exhaust ports?

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    Quote Originally Posted by Mild Thunder View Post
    I agree a 10-71 would probably be fine for what hes doing. We were thinking the 14 turning slower would net a little cooler setup, plus allow for future builds that might go up in cubic inch. Engines are going in a 42 Fountain with SCX drives. 0-60 times aren't important, boat will spend its life at 3000-6000rpm. I personally would rather see him get some better heads, and lower the boost, but, like everything, budget limited. I'd imagine going to some better flowing heads would net quite a bit of power over those edelbrocks and their poor exhaust ports?
    Better heads will lower the boost.
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