Oldscoolnew

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.

PREDATOR-Z

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).

redtan

iTrader: (5)

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.

S10xGN

iTrader: (11)

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...

2000ultraZ1911

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.

2000PewterT/A

I know of countless motors running 11.1 and above for a long time with no problems. As long as you have the right parts and a good tune you should be fine.

SNLPerformance

iTrader: (15)

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.

Oldscoolnew

My DCR at 11:1 with the cam I purchased is 8.79:1 is this going to be an issue?

mark21742

Most people say the max is 8.5:1 for 92/93 pump gas but ive seen a few running as high as 9.0:1. Just be careful with your tune and you might pull it off.

Im running 12.5:1 scr with a safe 8.22:1 dcr in my 408

96lt4c4

iTrader: (5)

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.