Higher compression on 4G63
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Higher compression on 4G63
So I see that some shops are starting to do slightly higher compression on 4G63's (10.5:1).
My head has to get shaved so I was wondering.....number one is there a formula for how many thousandths the head gets shaved when put back together with a OEM head gasket how high the compression is (IE: Lets say its shaved forty thousandths would that make compression 10:1.......I'm no mechanic and even further from being an engineer so hopefully someone understands what I'm asking).
And two is that ok to do on a relatively stock block? I come from Honda's so I'm used to high compression and I always like how high compression high boosted motors performed but since this seems relatively new to the Evo world not sure if this wise.
My head has to get shaved so I was wondering.....number one is there a formula for how many thousandths the head gets shaved when put back together with a OEM head gasket how high the compression is (IE: Lets say its shaved forty thousandths would that make compression 10:1.......I'm no mechanic and even further from being an engineer so hopefully someone understands what I'm asking).
And two is that ok to do on a relatively stock block? I come from Honda's so I'm used to high compression and I always like how high compression high boosted motors performed but since this seems relatively new to the Evo world not sure if this wise.
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A general rule of thumb is 1mm changes the compression ratio by 1.
0.004 in. is 0.101mm so it shouldn't raise the ratio that much.
I've never done it, but if I ever did do it I'd feel better with forged pistons, rods, and head studs.
0.004 in. is 0.101mm so it shouldn't raise the ratio that much.
I've never done it, but if I ever did do it I'd feel better with forged pistons, rods, and head studs.
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There is an easier way to achieve your desired compression ratio...
JE Pistons offers off-the-shelf pistons that provide a 10.0:1 compression ratio: http://www.jepistons.com/Catalogs/Sp...i/4g63_22.aspx
To answer your question, you'd have to calculate the volume loss in the chamber after machining the head .040". Then you can proceed with CR calculations as normal.
JE Pistons offers off-the-shelf pistons that provide a 10.0:1 compression ratio: http://www.jepistons.com/Catalogs/Sp...i/4g63_22.aspx
To answer your question, you'd have to calculate the volume loss in the chamber after machining the head .040". Then you can proceed with CR calculations as normal.
#6
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.040 thou would be immense decrease in chamber volume.
Easy way to calculate is to go here-
http://www.eaglerod.com/index.php?op...id=7&Itemid=25
change the headgasket thickness from .051 to .011 and see what happens
Aaron
Easy way to calculate is to go here-
http://www.eaglerod.com/index.php?op...id=7&Itemid=25
change the headgasket thickness from .051 to .011 and see what happens
Aaron
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