INTERNAL ENGINE MODIFICATIONS Valvetrain |Heads | Strokers | Design | Assembly

Compression

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Old Dec 27, 2011 | 07:20 AM
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Question Compression

My buddy threw together a 6.0 over the past few days. It consists of a fresh hone, new bearings, stock crank and rods, a set of coated lq9 flat tops, all with stock bolts. Cam is a comp 220/220/114, with a set of home ported/cleaned up 241 heads from his 02 camaro with stock mls gaskets. What kinda compression ratio and power you think this will make?

It's got a built 60e(good clutches, trans go, vette servo, sun shell) stock converter with 4.56 gears.

It's in a 99 ext cab z71 with 33's. Stock exhaust with a borla xr1 exiting in stock location. Stock intake and throttle body and stock air cleaner and tube.

Thanks
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Old Dec 27, 2011 | 03:21 PM
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im gonna guess 11.5:1?! anybody
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Old Dec 27, 2011 | 04:48 PM
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From: JunkYard
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Well the factory 6.0 heads are around 71 cc with the 317 heads and the 241 heads are around a 66 cc
Every 7cc is 1 full point of compression so with around 10:0-1 that would put him around 11:0-1

Gasket thickness and any milling would also affect this.
The LQ9 put out around 345 horse at the fly wheel on a stock tune from the factory so it will easily be over 400 at the fly wheel.
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Old Dec 28, 2011 | 07:09 AM
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LQ9 with 243 heads (basically an iron LS2) is 11.0:1. 243 heads are 64cc.

LQ9 with 241 heads with 66cc chambers is probably around 10.7:1-10.8:1 according to calcs.
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Old Dec 28, 2011 | 07:49 AM
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Thanks guys.
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Old Jan 6, 2012 | 02:03 PM
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7cc per compression point is not always correct, it vary by how high of compression youre actually at. a 16:1 compression engine will change half a compression point with 2cc less combustion chamber...to change an 8:1 compression engine half a compression point it takes 8cc less combustion chamber. not always a good rule to follow
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Old Jan 6, 2012 | 02:28 PM
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From: JunkYard
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Originally Posted by bmd_CL
7cc per compression point is not always correct, it vary by how high of compression youre actually at. a 16:1 compression engine will change half a compression point with 2cc less combustion chamber...to change an 8:1 compression engine half a compression point it takes 8cc less combustion chamber. not always a good rule to follow
There are several variables to consider but it works for most of this stock stuff. It always best to measure everything for the most accurate number.
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