I read through what seemed like an endless amount of threads regarding this topic and I read cheetah's comment that he had a client with a head milled 30 thousandths running ctr pistons and also I came across 616 saying that he was running a head milled 40 thousandths with ctr pistons. I personally have a jdm ITR motor with complete skunk2 valvetrain (including skunk2 stage 2 cams) and my head is milled 20 thousandths. I am planning to drop in ctr standard bore pistons in order to bump the compression and I realize I will need hondata or something of the like to tune the car properly (I have a vafc currently), according to the c-speed calculations my compression should be around 12.47 and I know of a fellow at raceline development who also has a jdm r motor with ctr pistons (the head is NOT milled) but he is employing a spoon 1 piece head gasket...I calculated his compression on c-speed to be around 12.44. I definitely plan to clay test the motor and double and triple check the clearances, but my real question I guess is whether this compression calculation is accurate? And I'd also appreciate any knowledgeable experiences/opinions regarding this set up and/or set ups that others have had similar to my own..thanks in advance and sorry for the long post!

 

sorry I forgot to mention that I calculated my compression with a honda oem 3-layer head gasket...thanks

 

compression will be well over 13:1. Id say about 13.2-13.4.

i would suggest a really good tuner or a forged piston with a little less dome

 

Can you give me the equations or the manner in which you came up with that compression number? What exactly does the c-speed calculator leave out? thanks in advance!

 

I know pretty much nobody believes this, but the compression height on a CTR
piston is about .03" more than other b pistons.

 

That's crazy talk, Sakai! (j/k, and waiting for the non believers)

 

I believe it if sgT says it

 

So is it safe to run Jun 3s or other high lift cams on a non milled head if the block has ctr pistons.

 

Hey, Steve, go sell crazy somwhere else, we`re full here.

(jk)

 

i know of someone that had a head milled .065" with no clearance problems with JUN3 cams.
But i would still clay it to be sure.