hey peeps ive been looking for some place to tell me what compression ratio is, and how to measure it. duz anybody know of a place that goes in depth on that subject?

 

go to C-speedracing.com and go to tech, and then compression ratios.

First, you need to find the cylinder volume. You'll need to convert the bore and stroke to centimeters. Clyninder Volume= ,x(1/2 bore)sq. x stroke

You need to find head gasket volume.
Cylinder Volume=,x(1/2 bore)sq. x gasket thickness.

Find your piston dish volume, which is hard to do, so get it from the manufacturer.

Ring Land Crevice must be found.
Ring Land Volume=,x bore x piston-to-wall clearance

Find Cylinder head volume from manufacturer or other reliable souce.

So, add up all the volumes and the BDC volume of one cylinder. Say it's 497.65cc. At TDC, say it's 39.05cc. Divide TDC into BDC and that's your compression ratio. For these, it would be 12.7:1

<------Emerica under different user name

 

coo thanx, so that compresstion ratio that u said at the bottom is that a good ratio or bad?