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Thread: supercharge a 11.5 to 1 engine?

  1. #1
    Club Member wikdsvt's Avatar
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    Default supercharge a 11.5 to 1 engine?

    Lets say I have a 347, stock block, running 11.5 to 1 compression.

    without lowering the compression, can I slap a supercharger (centrifugal s/c) on it?

    To lower compression, can I go with a multi-layer head gasket and then s/c it? Will the head gasket hold up? I prefer not to swap out pistons. any other ideas
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    Club Member AutoRoc's Avatar
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    Those thick copper head gaskets might work. I remember seeing someone use a .250" gasket for what you are doing and it worked. Honestly i would try it as is. As long as you keep the boost cold, compression shouldnt matter. 11 degrees of additional air temperature per pound of boost is the rule of thumb. My inline 6 is 10.3:1 stock compression and it sees 15psi on 93 octane. It has a tiny meth kit and an ambient temp A/W cooler. It has run without meth just fine and it also has run with the meth and no intercooler just fine. Now....if you are running a big cam, that probably bleeds off a bit of compression vs. a stock cam.

    Do it. I would feel fine trying 8psi on 93 octane, pull 8 degrees of timing out of it to start.
    Denny Villemure
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    Club Sponsor ReiKo's Avatar
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    Your only restriction will be what fuel you can use or what to use...
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    Forum Member soap's Avatar
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    Use good fuel for the amount of boost you want to run and keep your timing in check, shouldn't have any issues.

    --Joe

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    Club Member DRAG-ULA's Avatar
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    I'd also try it as is. You don't want to run a 1/4" think head gasket as a crutch. You lose all your quench in the head & it'll become more prone to detonation, which is bad.
    I used to be 'with it'. Then they changed what 'it' was. Now what I'm 'with' isn't 'it', and what's 'it' seems weird and scary to me.......



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    Club Member The Man's Avatar
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    The common read threshold for a stock block is 400 HP before it cracks the valley....just an fyi. Google it and see some cool carnage.

    I have a 10.5 to 1 327 with 10 lbs of boost tuned with 93....




    Sent from my XT1254 using Tapatalk 2
    Last edited by The Man; 09-23-2016 at 07:11 PM.
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    Club Member Beigg's Avatar
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    What is the LSA and duration of the cam?

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    Forum Member MYSTICAL's Avatar
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    E85 ftw!

  9. #9
    Club Sponsor 347convert's Avatar
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    Quote Originally Posted by The Man View Post
    The common read threshold for a stock block is 400 HP before it cracks the valley....just an fyi. Google it and see some cool carnage.

    I have a 10.5 to 1 327 with 10 lbs of boost tuned with 93....




    Sent from my XT1254 using Tapatalk 2
    I've broke a 302 block in half lol. 11.1 to 1 and 7600 rpm.

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