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Old Jan 23, 2011 | 11:05 PM
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Default Compression Estimates

I currently have an LQ4 factory shortblock with 243 heads on it. I was offered a good deal on a factory LQ9 shortblock. What would my resulting compression be with an LQ9 and 243 heads, and would it be too high for pump gas? Thanks
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Old Jan 23, 2011 | 11:41 PM
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Compression will be excellent, 11:1. And not too much for pump, I might be wrong but you have to be around twelve to one to start worrying about race gas lol.
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Old Jan 23, 2011 | 11:54 PM
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What he said.. It should be right at 11to one if you use a stock headgasket. And will be fine with 91or 93 octane I have heard ppl say over 11.5 to one is where you start running into problems on pump gas but no real experience there.
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Old Jan 24, 2011 | 01:21 AM
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10.2:1 is where it starts on a non computer controlled locked out timing engine with iron heads. these LS motors are a thing of beauty between the computer controlled timing the aluminum heads and chevy magic they can get up to about 11.5 sometimes 12:1 static with a big cam before you have the first issue. sounds like a cool build, good luck
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Old Jan 24, 2011 | 10:43 PM
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I am running carb, but think I should be fine @ 11:1, thanks!
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