Compression ratio formula

[manuel]

Can someone tell me how to figure out the actual comp. ratio for my set up ?, I was going through some receipts on my engine and the pistons I thought were in there are not, what I have are Speed-Pro 11.31 : 1 race pistons, the co. states these numbers are with 100.9cc chambers, I have 049 heads with 122cc chambers, so what would the actual ratio be ?, I wish I didn't have these in there, it's a 25' 3800lbs. daycruiser not a race boat, I would rather be able to burn cheaper fuel since it's going to be slow no matter what we do.
Manuel

[Blown 472]

Try this, page down you will see where to figure it out.
http://www.kuhlsuperchargers.com/tech%20p05.htm

[Oldsquirt]

Manuel, if you go to the Federal Mogul/Speed Pro website, right here (http://www.21cgt.com/FMWebCatalog/default.htm) and work your way to the pistons page, you can find the compression ratio. Unfortunately it doesn't look like they show yours wwhen used with a 122cc head. However, with the 119cc head, the compression is 9.6 to 1. Figure a drop of a couple tenths for the larger chambers. These are "ballpark" figures, of course.

[manuel]

Thanks OLDSQUIRT, that sounds more reasonable, I don't have all the specs. to figure it out on the calculators and I just wanted a ballpark figure because 11.31 : 1 just seemed like overkill and a waste of money in a boat like mine,