i got a ITR head that has a mild PnP job 5 angle valve job, full ferrea 6000 valvetrain. with skunk2 pro1 cams. i need to build a bottom end for the head i was thinking of doing
GSR block
rs machine 81mm pr3 pistons
2 layer buddy club HG
LS crank and rods
balanced crank
shot peen the rods
would this build be ok for the skunk2 pro 1s or would i need something with more compression?

 

Your compression will be roughly 11.4-11.5 depending on the thickness of that HG (which I think is .020 in.). If you used a P30 piston you will yeild a slighty higher CR. I would stick with the setup you have listed, the CR should be fine with a Pro 1 cam.

 

I forgot to mention that CR is with stock deck heights.

 

yea im keeping the deck heights stock. i was looking for p30s but cant find any.

 

If your keeping the stock bore you can find OEM ones from the stealership, or you can possibly call RS machine and see if they can cut some?

 

the ones i really wanted to get where the pr3 81.5mm pistons but i ask rs machine ebay seller if he had any and he said they were out. they only got 81mm and 82mm im kinda scared to run the 82 mm thou dont want to crack the sleeves

 

82mm is feasible, but if you score a wall and need a bore or hone your SOL. I would stick will your bore size and do some searching for pistons or combinations that you will yield a 12:1 CR with. You should be just fine with that compression ratio and pro 1's. Pro 2's like the CR a bit higher.

 

the only stock piston that would put me at 12:1 is the ctr right? i dont really want to use those. i was looking for some jdm itrs but cant find any

 

i ended up finding some OEM jdm itr pistons std size