cr on pump gas

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Dec 21, 2006 | 06:21 PM

osolow

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Posts: 170

cr on pump gas

how much compression can i run on a 6''rod 381 and still use super unleaded? I will probly be running an le4 or gm 847 if this matters.

Dec 21, 2006 | 07:59 PM

osolow

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Posts: 170

any1?

Dec 21, 2006 | 11:12 PM

grammerman

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Joined: Jun 2006

Posts: 196

From: Birmingham, AL

Search for DCR or dynamic compression ratio. Conservatively you might want to stay around 8.5:1. There are DCR calculators (google it) that will take specs from your cam, engine and your static compression ratio and estimate the DCR. I'd guess that static compression might somewhere between 11 and 12:1 but DCR is what you really need to figure out.

Dec 21, 2006 | 11:43 PM

Wild1

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Joined: Oct 2002

Posts: 2,277

From: Orange Kounty, Kalifornia

Absolutely, it's all about the Dynamic Compression Ratio. You can find calculators on the internet, I like this one.

http://www.empirenet.com/pkelley2/DynamicCR.html

The article talks about thresholds between 7.5 and 8.5 but that is for non-reverse cooled heads. With an LT1 you can be safe around 8.5 to 9.0 (limit pending gas quality)