I have a fully custom exhaust (2.25"), and have upgraded my entire fuel/air intake/ingition system, including skunk2 IM, high flow rails and injectors, wider throttle body w/spacer/ iridium plugs with new wires, etc. I plan on installing a set of Skunk 2 stage one cam gears along with new spirngs, retainers, and valves. What would you guys suggest for the compression on the new pistons I will buy. I was looking at 11.0:1 . Is this too high or low for my mods?Should I buy new rods? The engine is at 60K MI. Thanks

 

i'm assuming you have a gsr...with ur mods i probably get some stage 2 cams, the springs and retainers are a good idea...for compression gsr are 10.5.1 11's would be fine...rods aren't necessary unless ur gonna be pushing more than 300hp...

 

gsr's are 10.0\1 not 10.5\1 and the sirg in japan is 10.6\1

 

i'd go with the about 11.3-11.5 so you can stay on 91/92 octane.
And guess what? I got some b16a2 pistons that would exactly bump up that compression to that level! IM if your interested.

besides that.. 11.5 is the "safe"point for 91/92 octane. So unless you got 94 or so, you would have to do some tunning.

 

Hey everyone thanks for hte post. SOrry but i thought I had my car listed in my sig, my bad, anyways I have a 95 GSR. And the highest octane I can get in montana is 91, so you guys think 11+ on the compression? I want to get as much power as I can while keeping the engine naturally aspirated. Thanks

 

Yep what he said... PR3 pistons. I plan on using these .25 over with a Mugen gasket and try to be in the range of 11.6:1-11.8:1. normal we have 93, but race fuel we can get 100,110(maybe 114). High lift cams love high compression.

 

since 91 is the highest, i would stay under 11.5. Plus tunning isn't cheap, and you have less margin for error whne you go too high of a compression when tuning.

Email me at Phat_Flava@hotmail.com if you want the pistons.

They will be cheaper then you getting Type R pistons.

 

So would 11.5 be safe or should i go 11.3?? What would those b16a2 pistons put me at?

 

www.c-speedracing.com

they have a compression calculator, I heard it was off by a little. That will be your best way to figure otu where you wanna go.

HTH

 

get JDM ITR pistons..should give you around 11.3-5 CR...great for stage 2s

 

Alright fellas these are the numbers I will list the piston and then the compression for my set up, these are all with OEM Headgasket
USDM B16A - 11.3744
JDM B16A - 11.5996
USDM B18C5 - 10.8632
JDM B18C5 - 11.3624
I am thinking the USDM B16As I would like to go with JDM B16As but like stated before 91 octane is the highest I can get. What do you guys think?The USDM B16 seem just about perfect.

 

These would be my first two choices... And later in the future if you wanna go up, just get a Mugen gasket and that should bring you up to 11.5 area... But I think the USDM pistons should be cheaper then the JDM R's... And you can also get away with 11.5 on 91 with the right amount of tuning, qhich you should be getting anyway since your getting all this stuff done. JMHO

But 11.3 will be just fine y0.


[Modified by GONG SHOW, 2:24 PM 10/10/2002]

 

The difference is pretty minimal I think. Your looking at about .1 compression ratio difference, and if you want, like the guy above me said, buy the headgasket. You probably know already, anything JDM or R, your looking at about 2-300 bucks from what I usually see (you could get lucky, but i doubt you'll find it for cheap).
Remember though, too high of a ratio = more tunning required.