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Lowering my compression

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Old Aug 10, 2009 | 01:05 AM
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Default Lowering my compression

Hi, considering adding a blower to my H/C/I ls6 in my Zo6. My compression is approx 11.2:1 and I would like to lower it. I am running AFR205's milled .024 and a .040 cometic gasket. How thick of a gasket can I run? I would like to at least bring it down to 10:1
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Old Aug 10, 2009 | 07:17 AM
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Originally Posted by 69dodgecharger
Hi, considering adding a blower to my H/C/I ls6 in my Zo6. My compression is approx 11.2:1 and I would like to lower it. I am running AFR205's milled .024 and a .040 cometic gasket. How thick of a gasket can I run? I would like to at least bring it down to 10:1
Your not going to make it to 10:1 with a gasket change. Are you still on a stock bottom end? You could always sell your heads to off set the cost of some new 72cc heads, that would get you down in the 9.5:1 range.
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Old Aug 10, 2009 | 08:23 AM
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sell your heads and buy some 317s.
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Old Aug 10, 2009 | 08:34 AM
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Get a thicker head gasket. Keep those heads and just replace the pistons if you do not have a built bottom end already. Everyone will say well since you already have it out just replace everything like rods, bearings etc...It's up to you what you want to do. I would get a piston that will lower compression and can take some abuse. Replace the rod bolts while you are at it.
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Old Aug 10, 2009 | 10:31 AM
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Flucut .080 intake and exhaust and run a .060 gasket, that will get you 10.4x>10.5 and you'll be able to run 7>8 psi safely with premium (more if meth used)
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Old Aug 10, 2009 | 12:43 PM
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selling the AFR's is an option, just really didnt want to since they are a nice head and I got them for next to nothing from a friend. Changing pistons at this time is not going to happen. Its in the plan but just not yet because when I tear it apart I am going to do it right. Studs, rods, pistons ect ect.....
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Old Aug 10, 2009 | 01:04 PM
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You can run boost on the compression your at just dont get greedy. Keep it low with high octane fuel, meth kit if you have the $$$ and a safe tune. Then save up and build a nice forged, head/cam moter with 9.5:1 (+-) compression and turn up the boost. Also dont skimp on the fuel system... If your master plan is to make 550 + to the wheels go for a dual pump set up right away.

https://ls1tech.com/forums/forced-in...rocharger.html
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Old Aug 10, 2009 | 02:03 PM
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My plan was 5-7 PSI, with a meth kit. Probably going to use a racetronix pump with a BAP and 60lbs injectors for now, then I will install a custom boost referenced fuel system using a A1000 or somthing along those lines.
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Old Aug 10, 2009 | 06:38 PM
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What would my compression be with the 317's?
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Old Aug 10, 2009 | 06:45 PM
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Open the chamber up a couple, add thicker head gasket and maybe flycut a hair if needed.
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Old Aug 10, 2009 | 07:56 PM
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Originally Posted by 69dodgecharger
What would my compression be with the 317's?
I'm running a flat top piston with -4cc dish, 72cc 317 heads and a .052 cometic gasket and I'm around 9.4:1 compression. So with a flat top pistion you'll be in the 9.6:1 compression.
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