compression

If the pistons have no valve relief's it comes up to 9.19 to 1. If the pistons have 5 cc valve reliefs it is 8.76 to 1. That's according to the calculator on my desktop dyno program. I've noticed some calculators vary a little so each number is give or take a smidgen.

You can also go here to figure it yourself

http://www.csgnetwork.com/compcalc.html

It seems to coincide with the Desktop dyno program to the T.