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How to lower compression on stock ls1 ?

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Old Jan 18, 2006 | 05:26 PM
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Default How to lower compression on stock ls1 ?
I want to lower my compression a little because im going to boost,. I was told if you swap lq9 heads on it will lower it. Is there any other ways you can besides getting into the bottom end, maybe different head gaskets ???
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Old Jan 18, 2006 | 05:31 PM
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A thicker head gasket will change the compression but not sure how much
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Old Jan 18, 2006 | 05:47 PM
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Can anyone help me out with what thickness i should get. Ig going with the 6.0 lq9 heads, i was told 54mm will bring it to about 9.2-9.4 to 1.
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Old Jan 19, 2006 | 10:04 AM
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Search in here, there was a Sticky with head CC's vs compression. Also there are compression calculators to help with the info you need.
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Old Jan 19, 2006 | 10:47 AM
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6.0L heads from a GM truck will lower ur CR

2002 LQ9 Aluminum found on 2002+ 6.0L High Performance trucks will make the compression ratio about 9:1...this head is alsmost the same as a LS6 head with imporved intake and exhasut ports

2001+ LQ4 Aluminum found on 2001+ Low Performace tucks with 6.0L will also make compression ratio about 9:1
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Old Jan 19, 2006 | 10:54 AM
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Every .005" thicker head gasket you use, the combustion chamber volume increases 1cc.
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Old Jan 19, 2006 | 11:45 AM
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thicker headgaskets is the worst way to lower compression IMO because of the effect on the squish/quench area.

I would consider unshrouding and polishing in the chamber before anything else.
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Old Jan 31, 2006 | 12:34 AM
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Originally Posted by white2001s10
thicker headgaskets is the worst way to lower compression IMO because of the effect on the squish/quench area.

I would consider unshrouding and polishing in the chamber before anything else.
I would buy the 6L heads, and have some headwork done to those. Run stock gaskets and call it a day. I was going to do exactly that but I'm going iron 370 real soon and a set of after market castings.
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Old Jan 31, 2006 | 12:51 AM
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http://www.diamondracing.net/cocalc.htm
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Old Jan 31, 2006 | 02:37 AM
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i dunno if you want to do it but since your lowering the CR i imagine you are going to be wanting to make some serious HP so might want to even consider a forged bottem end.
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Old Jan 31, 2006 | 03:54 AM
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Limit on stock bottom end is about 10# of boost and you can make that with stock CR, intercooler, good tune and water/meth injection on 93 octane pump gas.

Post it in FI forum for more feedback.
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