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Old Nov 2, 2018 | 06:22 PM
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Fletcherj1's Avatar
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Default Ls1 heads

Hi everybody.
just looking for some advice.
I know standard 5.7 heads have a combustion chamber of 66.67cc with the engine having a compression ratio of about 10.1:1. I want to up my compression ratio a wee bit. I have an intake that will flow 2500cfm of air. And the heads I am looking at have intake runners that flow 310cfm of air. Anyway back to the question I want to know what my compression ratio will be with 65cc, 64cc, or 62cc combustion chambers on standard internals. By standard internals I mean standard size stuff but brand new. I have tried using an online calculator to work it out using standard measurements I found online but couldn't even work out the standard CR to 10.1 properly. Anyway if anyone has any info to help me out abit would be great.
cheers

Last edited by Fletcherj1; Nov 2, 2018 at 06:28 PM.
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Old Nov 2, 2018 | 07:24 PM
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01CamaroSSTx's Avatar
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Originally Posted by Fletcherj1
Hi everybody.
just looking for some advice.
I know standard 5.7 heads have a combustion chamber of 66.67cc with the engine having a compression ratio of about 10.1:1. I want to up my compression ratio a wee bit. I have an intake that will flow 2500cfm of air. And the heads I am looking at have intake runners that flow 310cfm of air. Anyway back to the question I want to know what my compression ratio will be with 65cc, 64cc, or 62cc combustion chambers on standard internals. By standard internals I mean standard size stuff but brand new. I have tried using an online calculator to work it out using standard measurements I found online but couldn't even work out the standard CR to 10.1 properly. Anyway if anyone has any info to help me out abit would be great.
cheers
Just some rough calc's

Bore: 3.898
Stroke: 3.622
CH volume: 67cc (241 heads)
Effective Dome volume: 0.00
Deck clearance: 0.00
Compressed gasket thickness: 0.05
8 cyl.

______________________________
10.2:1 (stock 241 heads 67cc)
10.4:1 (stock 243/799/823 heads 65cc)
10.6:1 (64cc)
10.7:1 (63cc)
10.9:1 (62cc)
11.0:1 (stock 703/862/895 heads 61cc)

https://speedmaster79.com/tools/engi...ression-ratio/


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Old Nov 6, 2018 | 12:46 PM
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From: columbus,ohio
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Originally Posted by 01CamaroSSTx
Just some rough calc's

Bore: 3.898
Stroke: 3.622
CH volume: 67cc (241 heads)
Effective Dome volume: 0.00
Deck clearance: 0.00
Compressed gasket thickness: 0.05
8 cyl.

______________________________
10.2:1 (stock 241 heads 67cc)
10.4:1 (stock 243/799/823 heads 65cc)
10.6:1 (64cc)
10.7:1 (63cc)
10.9:1 (62cc)
11.0:1 (stock 703/862/895 heads 61cc)

https://speedmaster79.com/tools/engi...ression-ratio/
823 are not 65cc and will not work on 3.9 bore so those are not an option. Has anyone seen 895 castings ?
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