bumping up compression

[challengermike]

I am going to be pulling my heads off for a valve job so i was thinking of shaving the heads to bump up the compression some.My engine is .030 over and im running felpro 9441 gaskets with trw pistons.Would it be worth it to shave the heads or would i not gain that much compression wise?I would like to get as close to 9 to 1 as i can.

 

[bison]

Not going to happen. What is your cr now?

 

[challengermike]

im not sure what it is.If it helps at all heres a link to the pistons.
Sealed Power ZWL2481F30 - Speed-Pro Forged Pistons - Overview - SummitRacing.com
as far as i know the block wasnt decked and the heads havn't been cut yet.

 

[bison]

Assuming your deck height is 9.520, gasket is .051, and combustion chamber 47cc you are at about 8.15:1. If you reduced the combustion chamber to 42cc you would be at 8.57:1. It would take a lot of milling to get that. I wouldnt do it. The castings are to thin as it is and you will have to mill the intake to get it to fit correctly. Going to a .040 gasket would be 8.32:1. On a 3.83 bore every .010 you get the top of the piston closer to the deck will increase the CR by roughly .16 with those pistons.

 

[Red C5]

Why not just turbn up the boost?

 

[TURBOPOWERED68]

Does the higher CR help with the initial spool up of the turbo??

 

[TurboTnZ06]

Don't do it. You'll also have the pushrods acting like they are longer too.

 

[challengermike]

Im already running 28 #s of boost.I was thinking it would help spoolup some.I see that rjc headgaskets are .027 to .033 compressed thickness,i was just thinking alittle off the head and the thinner gaskets would get me close.So if i were to just go with the thinner gaskets would it be worth it for that little increase in compression?I understand that the pushrods may need to be changed.

 

[DMan]

Just get a bb turbo or a higher stall tc

 

[challengermike]

I did order the RJC gaskets today.Do you think i would have to worry about pushrod length if i just use the gaskets and no shaving of the head.If what bison posted above about the felpros being .051(im not sure of there thickness) and the rjc being .033 its about a .018 difference.