I know one pro and thats being able to change your compression but what about the cons?
can you have a 6.0l heads with a 67cc and have problems cause the cc was changed?
I need 67cc cause it equals out to 10.9.1 compression with my -6cc pistons.

I dont want to have to worry about something going wrong with the heads a year or 2 later so if I cant do this safely then I guess I will just have to save up for LS6 heads.

 

8,000 trouble free miles on my welded 59cc chambers. I'm a beliver in them if they are done by a competent company that has researched the process and follows proper heat treating guidelines after welding.

 

thats good to hear

does anyone else weld them besides PP?

would also like to hear from some others

 

If you have a 3.90" bore engine then a 6.0L head does not flow like a LS6 head due to the air coming out into the as cast 4.00" size chamber of the 6.0L casting and then hitting the top of the bore, inducing turbulence. This and the fact that a 6.0L casting is 70cc and only yields about 9.5:1 compression is why PP decided to weld the castings they have to the smaller bore. Take my Stg 2.5 LS6 heads, on a 4.00 bore they flow 325 @ .600" on a 3.90" they still flow 320 @ .600", the same program in a 6.0L head flowed 324 @ .600" but on a 3.90" bore they only flowed 309 @ .600", all of this was flowed in house on our bench. So you can see how having the chamber diameter bigger then the bore hurts the airflow.

If you have a 4.00" or bigger bore engine then it doesn't make sense to weld up the chambers to the smaller diameter, just to have to port it out to 4.00" diameter where it needs to be. If a head can be milled a small amount to achieve a desired compression ratio then that is the way to go. So in short, get some 6.0L heads, we have new cores for $400 a pair, and mill them .018" to get to the 67cc that you need. There will be no problems milling these heads this amount, we mill practically every head we do at least this much. And it doesn't make sense to buy LS6 heads only to have to port the chambers out to a 4.00" bore and try to make them 67cc. Hope this helps.

 

thanks,
I tried to call you but you guys just closed

I thought a 67cc would flow more on my bore 4.040?
can 6.0l milled flow as much as your new stage 3 LS6 did 335-340cfm with my bore?

also how much more milling would it take to get my compression to 11.1?

stock height gaskets and -6cc pistons
with 67cc I had it made out to 10.9.1

also with this big of a cam in my sig and milling would I have P-V problems? I think these pistons come with 2.0 valve reliefs?