offaxis

iTrader: (19)

Hey I am not sure if this is the right section for this but I have an 06 gto that I am installing a aps TT kit on. I would like to drop my compression from the stock 10.9 down the about the 9.5 range. What are my options? and what heads are you guys running?


I have been looking at some lq9 heads but withthe 72 cc I think that will only bring me to 9.9 . Anyone have a head with a larger CC? Also is it worth getting a ported heads and do I need stainless valves??

EATON22

YOu may be able to get here with those heads and then order a special MLS Head gasket that is about 3 times as thick as your stock one. You could get down to 9.6 or 9.7.
The only other suggestion would be to replace pistons; which you need to do if y ou are going to run over 9-10PSI. IF you do not do it now; sooner or later you will becasue you will pull your wring lands on your stock set up pistons.

ls1290

iTrader: (20)

Though people go that route, it is not recommended. The thick head gasket affects the overall quench of the combustion chamber. I know a lot of shops can open up the combustion chambers of 317 heads to 74cc or 76cc.

Keith

52172

iTrader: (2)

quench is not very important with forced induction that rule applies to NA motors where it is very important. So the thicker head gasket shouldn't be a problem as long as you stay under around 15 psi. Opening up the combustion chambers and thicker gaskets if you do not want to replace your pistons is what I would do.