LQ9 6.0 heads?
LQ9 6.0 heads? I'm hoping i don't have a problem here. I bought a set of 6.0 truck heads to lower my compression for my D1SC kit. Now my heads are the LQ9 035 casting not the LQ4 317 casting. I thought i read that the LQ9's are about a half a point higher in compression than the LQ4's. When i ordered my Diamond 9.0:1 blower pistons i thought my heads were the lower compression type.
GTP removed material from the combustion chambers on my heads and my pistons are 9:1's, so actaully can i expect to see my compression close to 9.5:1? I was planning on running about 12 to 14#'s but if the heads are have a higher compression i don't want to have any trouble. I looked at the chart ATI gives ya and even with 9.5:1 12#'s is OK, but it wasn't what i was aiming for. What should i do to see what my compression is? Doing a CC volume test would be first right? I'm finding this strange cause i thought i read that both LQ9 and LQ4 heads have the same size C chambers. Yet LQ9 ( Cadillac Escalade ) heads are almost a half point higher. Man, can anyone shine some light on this? I just want to run high boost safely. Thank god GTP only milled .007 from the heads. They took the time to call Diamond to find out all the specs on my pistons to tailor my heads for what i needed. So now i think about it maybe GTP removed the right amount of material based on my desired CR and what gaskets i was using to keep my CR as close to 9:1. Damn good pride in his work to go that far. Well post any ideas or comments anyone might have about these heads. Sorry for the long post. I just wanted to let everyone know what i found out.
Den
GTP removed material from the combustion chambers on my heads and my pistons are 9:1's, so actaully can i expect to see my compression close to 9.5:1? I was planning on running about 12 to 14#'s but if the heads are have a higher compression i don't want to have any trouble. I looked at the chart ATI gives ya and even with 9.5:1 12#'s is OK, but it wasn't what i was aiming for. What should i do to see what my compression is? Doing a CC volume test would be first right? I'm finding this strange cause i thought i read that both LQ9 and LQ4 heads have the same size C chambers. Yet LQ9 ( Cadillac Escalade ) heads are almost a half point higher. Man, can anyone shine some light on this? I just want to run high boost safely. Thank god GTP only milled .007 from the heads. They took the time to call Diamond to find out all the specs on my pistons to tailor my heads for what i needed. So now i think about it maybe GTP removed the right amount of material based on my desired CR and what gaskets i was using to keep my CR as close to 9:1. Damn good pride in his work to go that far. Well post any ideas or comments anyone might have about these heads. Sorry for the long post. I just wanted to let everyone know what i found out.
Den
TECH Resident
Joined: Aug 2003
Posts: 948
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From: orlando, florida
The differance in compression bettween the lq4 and lq9 motors is in the pistons not in the heads both heads have 71cc chambers. So if your using 9:1 pistons and bolt on a set of lq9 heads you'll be looking at around 8.5:1 compression.
Thats good to hear..Now i think about it, i did tell Diamond that my heads had a 72cc chambers and that i wanted 9:1 based on that. So i guess i'm right where i need to be.
Thanks.
Thanks.
