alright my setup is a ls/vtec (a pr3 head and a b18a block) with Crower Stage 2 63042-2 cams duration at .050" 255 int and exh 248, and i have pct pistons. When I finished building the motor I did a compression test and it was around 190 for all cylinders are these numbers too low? the compression calculator says I should be a 13:1

 

You did have the throttle open all the way when you tested right?

 

Should be around 230 + for 13:1.

11:1 is around 190 - 200

 

thanks for the answers

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by snowseeker &raquo;</TD></TR><TR><TD CLASS="quote">Should be around 230 + for 13:1.

11:1 is around 190 - 200</TD></TR></TABLE>

Really? I thought there wasnt a direct relation with the two. What formula did you use?

 

Its just a rough estimate going off of CR. I have a small chart that gives an average range of psi for CR's.

 

I went out and took a look at the chart again to make sure. It goes up in 20 psi incriments.

CR----------------average psi

8.0:1------------140
9.0:1------------160
10.0:1-----------180
11.0:1-----------200
12.0:1-----------220

I am sure these can off with diffrent setups, valves, chamber work, head gaskets, ect. They have always been pretty close for me. It is just a base to go off of.