Compression question for ls vtec
 

So I am building the lower end of a b18b1 that I have in my garage. Right now I am shopping for some new pistons, wanted to keep with the OEM. Originally I was looking at the JDM type r pistons 11.1:1 I believe. But I was thinking that I want to run just a little higher compression. Don't really know whats still safe with pump gas. I was looking at the CTR 12.2-3 in the b18 from what I have heard, please correct me if I'm wrong. As far as the vtec head I plan on going with the GSR, increase of .2 compression. I just wanted to get some feedback before I go and start buying parts. Other things for the bottom end on my list were new OEM rod/main bearings ARP rod bolts and some used GSR rods.

Here is a link that I stole a lot of this info out of
http://www.geocities.com/teampimports/lsvtec.html

you dont need tons of compression to make good power. the info in that link is wrong. ctr pistons and a gsr head puts you at 13:1 or more. way to high for pump gas. p30 pistons are a better alternative. they're lighter, have a better dome, give you just enough compression, and you dont have to mod the rods to make them fit.

Ok, well I'm still looking around and came across this
http://www.ff-squad.com/tech/temp/pistons.htm
From my understanding it says the with CTR pistons and a GSR head I would run 11.8:1 or more which doesn't make too much sense because with the JDM ITR pistons would be around 11.3-4:1. I might just go with the p73 JDM...

Even around 12:1 you should be ok as long as you're running premium. I'm running 13.5:1 with my GS-R and run 93 octane in the winter, the temp outside makes a difference.

So what hp you're looking for? Also what shell is the B18B going in?

I don't have a hp goal... I am in the process of getting my ASE certification and had the option to take some machining classes. So this term I am taking lower engine machining. In the fall I bought a 95 Integra that had a bad motor, in the middle of putting a JDM b18b1 + tranny in it. So with the old motor sitting around I thought I would build the ls vtec that I wanted. This will be going in my car when I'm done (listed in Sig) I do weekend drag racing at the local track here.

After reading this thread at Honda-tech I just don't know who to believe anymore...

http://www.honda-tech.com/showthread.php?t=717928


PR3 head/B16 Block

STD = 11.643438609136867
.25 OS = 11.703231023151065

PR3 head/B17 Block

STD = 12.193487116069006
.25 OS = 12.256369577319077

PR3 head/B18C Block

STD = 12.58636786521145
.25 OS = 12.649248792586258

P72 head/B18C Block

STD = 12.924594026551906
.25 OS = 12.989047869209281

PR3 head/B18A/B Block

STD = 12.825536009218106
.25 OS = 12.88971493738735

P72 head/B18A/B Block

STD = 13.170743903246784
.25 OS = 13.236528215133324

All calculated using OEM 3 layer gasket @ .026 and the compression height provided by Omniman

Well if that's the case, go with boring it oversized. You will see more gains here, without needing to raise compression as much.

there's no reason to run ctr pistons when p30 or jdm p73's give you plenty of compression and are a lot lighter

Yeah, after lookin around a lot I think I'm going with the JDM p73...