Compression ratio

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Jan 27, 2019 | 12:29 AM

jus1975

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Heel & Toe

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Compression ratio

Does anyone know what is a stock ls3 compression ratio. I'm reading 68cc and 70cc

Jan 27, 2019 | 09:14 AM

Patriot Six

Drifting

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From: Temecula, CA

68cc combustion chamber and 10.7:1 compression ratio.

Jan 27, 2019 | 10:24 AM

jus1975

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Heel & Toe

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That's what I thought but now I'm seeing 70cc in a few books I have. And specs on the heads are advertised with 70cc at summit and jegs and a few other places

Jan 27, 2019 | 11:09 AM

Patriot Six

Drifting

Joined: Jun 2016

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From: Temecula, CA

That’s probably aftermarket heads.

Jan 27, 2019 | 11:29 AM

jus1975

Thread Starter

Heel & Toe

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Nah. It was gm

Jan 27, 2019 | 11:54 AM

veneno

Racer

Joined: Sep 2013

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From: coconut creek, fl

I sent me heads to texas speed earlier in the week and asked them to mill the heads down to 66cc
He said the stock ls3 heads are 70cc

Jan 27, 2019 | 12:00 PM

jus1975

Thread Starter

Heel & Toe

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see what i mean. 2 different sources. 2 different measurements. Im confused. SPS says they are 68cc. Im dying over here

Jan 27, 2019 | 01:10 PM

Turbo6TA

Race Director

Joined: Mar 2011

Posts: 13,262

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From: SW Florida

2021 C6 of the Year Finalist - Modified

LS3 Cylinder Heads . . . .(0821 Casting)

Intake Valves: . .. - . 2.165" Hollow Stem Stainless

Exhaust Valves: . .. . 1.590" Solid Stem Stainless

Head Chambers: .. .. 70cc

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Jan 27, 2019 | 01:24 PM

old motorhead

Le Mans Master

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From: Southeast TX

What's the end game here? Why does it matter? If you remove a similar amount during the milling process or add a thinner head gasket, the results are not going to differ that much.....whether 68 or 70cc.