that is , b17 head & block rods valvetrain … what kind of CR should be expected…
… what exactly is the benefit of an overbore on the pistons…? is that meant jus for a motor that has been over bored or can i cram those into a stock motor with any benefits?
according to the FFSquad:
usdm itr pistons in b17a: 10.6ish
jdm itr pistons in b17a: 10.8ish
according to that compression ratio calculator:
usdm itr pistons in b17a: 10.04
jdm itr pistons in b17a: 10.52
Pretty big discrepency, so i’m really not sure which to trust.
As for oversized pistons, they won’t fit in the stock bore. I suggest getting the oversized. They are the same price, you will increase displacement a little (hey, its better than nothing), and actually you’ll increase compression a little too.
Here you go, finally a compression ratio calculator that is CORRECT!!! Have fun
http://www.c-speedracing.com/howto/compcalc/compcalc.html
10.72:1 with JDM ITR Pistons.
10.22:1 with USDM ITR Pistons.
Dont mean to post whore. Thanks Dan. Got these in the mail today!
That compression calculator put me at 11.08:1 (right where I anticipated) 
gosh dan, what would i ever do without you??!!!
thank you SO much for posting this. Now i know for sure. Cause i calculated it myself, then checked the FFSquad, and checked that other CR calculator and each had a diff answer.
but now, my personal calculations match up w/ the calculations on this CR!!! I can’t believe i calculated it right!! haha!
thanks again.
archivethis
No problem Colin. I’m real sorry I never got back to your e-mail. I thought I had and then I realized I didn’t. Louis, NICE PISTONS…heheheh :D.
What’s the piston-to-deck height? I’m not sure what to put for that.
Piston to deck height is the difference or “height” of the surface of the piston (flat surface) in relation to the deck of the block (top of the cylinder sleeves.
Thank You Dan for that site, Real quick can JDM ITR pistons take abuse well, example Nitrous one in a while ( 1 a month) mild shot like 50
Thanks Dan but I kinda figured that much. I guess I should have worded that differently. I meant how do I know which one to put for whatever application I’m figuring the CR for? Does it depend on the block or the piston?
For example:
b18a/b block
b16a head
USDM ITR pistons
P to D height-?
For LS VTECs, it’s different. That’s why they have you put your “measured” piston to deck height. But if you use a B16A block and any VTEC piston, you’ll use the B16A deck height (unless you are using PCT pistons because the deck height is in reference to a B18C block, not a B16A). So in essence, I’m saying I’m not sure ;). I’ve never personally done the LS/VTEC. I’ve calculated the piston to deck height for some LS/VTEC setups, but I don’t remember the numbers I came up with.
ITR pistons are cast just like all other Honda pistons. They can take as much NOS as the next Honda motor. I still don’t recommend NOS and would never use it on my own motor, but I doubt occasional use of a 50 shot on a tuned motor would hurt anything.
ty …nice work…gives me good idea as to what to prep for…