I am going to be building a GS-R all motor, daily driver... I don't ecessarily want to go to the extreme, power wise, but I will be selecting upgraded pistons and would be going higher compression for some more power. I would love to run 12.0:1, but that's getting too damn high for pump gas for my tastes.

I am looking into 11 or 11.5:1, but since I will be needing to mill the head some, I will prolly go with 11.0:1. Basically, I want considerably better than stock numbers, all motor, reliable on pump gas (92-93 oct). I am not particularly an all motor guy, so I am looking for any suggestions as far as compression goes for the piston. Keep in mind, the pistons will be for a slighly milled head (don't know how much until I take it to the shop, sorry) 30,000ths maybe ?

Also, what compression ratio would be considered not streetable... IOW, what is the max compression for 92 oct gas ?

 

Hmm GS-R with head milled .020~.030 I would have to say USDM ITR pistions would be the way to go if ya want to save a buck or JDM ITR pistions if ya want to push the edge on C/R with the milled ...as far as Solid #'s not for sure but I would have to say 11.3:1~11.8:1 C/R with the pistons listed above..
Hope that helps a tad' bit..

 

Personally I wouldn't go any higher than 12.5:1 on pump gas. I agree with the above post. What cams are you putting in?

 

I'd go with customs from JE...Get the head milled and as soon as it is done, order the pistons to those specs. That way you know exactly what you are getting and won't be worrying about valves clicking with your new pistons. Go 11 or 11.5:1, this is about as high as you can get without have to advance or retard your timing too much. Also you'll be able to run on 92 with no concern of buying octane boost (unless you want to).

 

Use this site to check the compression that you want and what pistons to use. http://www.c-speedracing.com/howto/c.../compcalc.html

 

That compression calculator looks pretty useful, I just have to get the head milled, then I'll 'cc' it and check the calculator for actual CR.

I was comparing pricing and have found that a set of JE's 11:0-1 with rings,pins and locks would cost me about $150 more than stock B16's that would yeild almost the same compression with the milled head 11.3 ish :1. I think I want to stay as close to 11.5:1 as I can. This car will prolly see nitrous in it's future for the strip, so I don't know if I want to go with stocker pistons due to the weaker cast design.
I want to go forged, and for the same money, I can get the SRPs...but why ? Anyone running JUN pistons one the board ? I am interested in their performance.

As far as [b]cams]/b], for right now, I will be running stock GSR cams in this car and eventually will pull the head to do some port and chamber work... at this time, I will prolly swap in a JDM ITR intake cam and possibly a CTR exhaust cam... gonna need to upgrade the springs as well, but damn.. without advanced timing... that car will be a little SOB to crank over..