Need help, piston?

[yogib]

I have been searching with not much luck.I have a 82 turbo motor that I want to build for my N/A car.It has the P90 head and dished pistons.From what I have been reading going to flat tops with this head I will only be running 8.8:1 compression.I would like to bump it to 9.5:1 to 10:1 or so for a nice safe street car.I dont want to shave the head and open that can of worms.Maybe run a thinner head gasket but I dont want a leaker down the road.So I either would like domed pistons or a GOOD safe excellent sealing thinner gasket to use.Like I said Ive searched and not found anything.I talked with A few guys on the phone and they dont like the .080 mill idea.At this point I dont plan to run a different head.Already have the P90 and Need new .030 pistons anyway.Any pistons that someone knows about would be greatly appreciated.Cast are fine for me.Expand slower and better for street car.

[BRAAP]

If your pistons are the OE or OE replacement cast flat pistons, at TDC, those pistons pop up above the block deck between .020”-.025”, which limits how thin of a head gasket you can use, i.e. the pistons come real close to contacting the head! The OE type head gaskets, Felpro, ROC, HKS/NISMO 1mm steel shim variety, etc, are all about as thin as you would want to go with the OE flat top pistons.

 

Weld up the chambers on both sides of the spark bolt to reduce chamber volume is an option, but will require the chamber to final shaped, (unshroud the valves while you are at it), and all the valve seats then “should” be replaced as the heat introduced in the chambers will distort the chambers surrounding the valve seats which could relax the press fit, subsequently dropping a valve seat! Not pretty.

 

Custom pistons with a dome that matches the chamber shape is also an option, but I am positive that you wont find ANY cast pistons in this arrangement. That will have to be a Forging. JE, Ross, etc are all good sources for custom L-series pistons.

[yogib]

It currently has the turbo dished pistons.What would you recommend for my setup?I have talked with you on the phone but we didnt address this issue much.P90,flat tops? gasket?If I can just run flat tops and a thinner gasket to get a decent compression ratio that would be fine.I just dont want to have to shim towers etc. etc...Mildly built best for money street N/A car is what Im after.With a mild cam of course and header.