I need to purchase a set of Forged pistons for my FI setup. Lookin into CP pistons, but not sure what Compression to go with.

First off, I have a GS-R (B18C1). I'm also putting in a Cometic 0.120" Head Gasket which will lower my Compression Ratio to 8.2:1 cuz it's so thick.

Now should I go with 9.0:1 Pistons or 9.8:1 Pistons?

Another quick question...

So if I get 9.8:1 Pistons and put the Cometic 0.120" head gasket in, how low will my Compressions Ratio be around? What about with 9.0:1 Pistons?

 

 

**** the headgasket and just get 9:1 pistons

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Deckedlude &raquo;</TD></TR><TR><TD CLASS="quote">**** the headgasket and just get 9:1 pistons</TD></TR></TABLE> agreed

 

run an OEM gasket and jus get 9:1 pistons.

 

hmmm... why not both? The Head Gasket AND some Forged Pistons? I would use an OEM HG, but I already spent $120.00 bucks on this Cometic HG. They told me it would be great for Boosted applications.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by B00ST2nR &raquo;</TD></TR><TR><TD CLASS="quote">hmmm... why not both? The Head Gasket AND some Forged Pistons? I would use an OEM HG, but I already spent $120.00 bucks on this Cometic HG. They told me it would be great for Boosted applications.</TD></TR></TABLE>

Why both? A thicker headgasket destroys your quench, messes with your cam timing, and is more prone to blow out because it's thicker. Running 9:1 Cp pistons and a .12" cometic will result in 7.6:1 compression. Running 9.8:1 pistons and a .12" cometic will result in 8.2:1 compression. That 8.2:1 with the massive head gasket will probably handle as much boost and power on pump gas as a 9:1 motor with a stock thickness headgasket. Return or sell the headgasket, run some 9:1 pistons, and be done with it. A thick headgasket just adds too many headaches, especially if you're going to run low comp pistons anyways.

 

Thanks for the info fellas.

 

You could just mill the head to get the compression where you want it.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by fast94ex &raquo;</TD></TR><TR><TD CLASS="quote">You could just mill the head to get the compression where you want it.</TD></TR></TABLE>

that just makes **** complicatd. keep it simple.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by project dc2 &raquo;</TD></TR><TR><TD CLASS="quote">

that just makes **** complicatd. keep it simple. </TD></TR></TABLE>

Yep.

I just got myself some 9:1 CP Pistons with Eagle Rods. I'll be using a stock Head Gasket.