I’ve been searching for P30 pistons and was under the impression that P30 was the JDM 2nd Generation B16 piston.
I spoke with the Honda dealer and he said that the 99+ Civic Si pistons were also “P30” pistons.
Are the 99+ USDM Si pistons the same as JDM SiR2 pistons?
You can use JDM b16A (PR30) and USDM b16A (PR3) pistons directly on LS rods without having to mill the small end of the rod."
The A2’s or A3’s might be different. SRP makes an off the shelf forged @10.5/1 for mid $300. I have a set, NOS, I might be able to get my hands back on it if your interested.
Schu
Schu, there is a difference in compression ratio between the PR3 and P30.
I have three P30’s sitting in my garage, I just need a fourth 
PR3 + B17A = 10.7
P30 + B17A = 10.9
.2 = Head gasket thickness
With a two layer gasket, I’d be running 11.25:1 CR with the P30.
Those numbers I posted were using OEM gasket thickness.
CTR’s = 11.36/1
I know, the problem is that I would then have to get the rods milled and reballanced to use the CTR pistons.
Your going to want to get the whole rotating assembly balanced anyway, beleive me.
http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=2450102789&category=33623
I am sure these guys can get you p30’s or maybe even 1
http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=2449465923&category=33623
Its difficult, i tried to source them and its nearly impossible, you would have to go through a Japanse Honda dealer if u could even get the part number… As far as the newer b16s being p30, thats BS, everyone would be getting the p30s then…
Thats the thing, I verified the part numbers for the 99+ Si and they were in fact xxxxx-P30-xx pn’s.
very strange duy. Until now I’d never heard of the p30’s being in newer Si’s. I’d definitely recommend the p30’s for a b17a though. Thats what both I and elmer are running. The p30’s are pretty hard to find. I bought mine new from jhp, I looked around a little for a used set, but never found any.
i was under the impression p30’s were in the newer Si’s and 1st gen jdm b16 and the pr3’s were out of the jdm 2nd gen. b16
How are the JDM ITR pistons in comparison to the P30’s? Those ITR pistons have 11.1 CR if I’m not mistaken and they have oil squirters. Bonus.
The ITR pistons have 11:1 in a b18c, that doesn’t mean they have that compression in every other motor. The p30’s in a b17a will yield 11:1, but JDM ITR pistons will yield a lower compression than that if installed in a b17a.
And the pistons do not have oil squirters. Those are a separate part which is installed in the block.
Ah yes, ok true about the difference in CR with different blocks. Forgot about that.
God I could listen to you talk all day Colin lol (no homo).