Longevity of higher 11:1 and 11:5 compression engines
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Joined: Jul 2013
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From: CT
Longevity of higher 11:1 and 11:5 compression engines Hey guys I'm building an lq4 and 243 heads and flat top pistons I want to mill the heads .030 to attain higher compression of 11:1. Just wondering how many miles u guys have on these engines? Worried about detonation or blowing a head gasket.
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From: BFE
For Detonation you have to pay attention to DCR not as much SCR. For 11:1 and 11.5:1 SCR you'll need to run 92/93 octane and have a came with less than 8.5 DCR.
Use MLS gaskets with no more than .045 quench and use proper plugs. (colder than stock).
Use MLS gaskets with no more than .045 quench and use proper plugs. (colder than stock).
Worried about detonation or blowing a head gasket.
Second of all 11:1 compression is not that high that you have to worry about longevity. LS2s come with 10.9:1 compression and those can run on even 91 octane with the stock tune.
Heck, even a 12:1 compression engine will be just fine if it has a good tune to combat detonation.
Are you talking about keeping the stock pistons? Not sure I'd go there personally, they're weak on a good day. With increased compression, everything has to be perfect or you're asking for trouble...
On The Tree
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From: new castle PA
redtan 10:53 AM Yesterday
Originally Posted by : Worried about detonation or blowing a head gasket. First of all, that all can be controlled by having a proper tune and using good 93 octane gas.
Second of all 11:1 compression is not that high that you have to worry about longevity. LS2s come with 10.9:1 compression and those can run on even 91 octane with the stock tune.
Heck, even a 12:1 compression engine will be just fine if it has a good tune to combat detonation
^^ I'd say he's right on.
Originally Posted by : Worried about detonation or blowing a head gasket. First of all, that all can be controlled by having a proper tune and using good 93 octane gas.
Second of all 11:1 compression is not that high that you have to worry about longevity. LS2s come with 10.9:1 compression and those can run on even 91 octane with the stock tune.
Heck, even a 12:1 compression engine will be just fine if it has a good tune to combat detonation
^^ I'd say he's right on.
LS7 comes with 11:1 compression from the factory, as mentioned DCR is more important as well as the tune. I would run a .040" head gasket before milling as that will increase compression and provide better quench without hurting airflow.
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From: PA/MD
Im running 12.5:1 scr with a safe 8.22:1 dcr in my 408
My compression is 11.8 my DCR is 8.5. I have no knock. Pretty much a stock LS1 timing table. Max timing at WOT is 28 degrees. Thinking of doing a cam swap this winter that will knock it down to about 8.
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