bore X bore X stroke X .7854 = displacement lets say 206 cc's
Add cylinder head volume (combustion chamber) Lets say 26 cc's
206 + 26 = 232 cc'c
232/26 = 8.92 to 1 compression ratio
When measuring the combustion chamber volume be sure to include the head gasket.
Probably the best way to measure the combustion chamber volume is to make a clear plastic (lexan) plate to bolt to the head gasket surface.
Put a 1/2" hole in the center of the plate.
Mount the head perfectly level and measure how many cc's of transmission fluid it takes to fill the combustion chamber with no air bubbles.
Compression “is” the Holy Grail. Of course you have to match your fuel octane to the ratio you have. The higher the compression ratio, the more octane you need. In case you didn’t know; octane is a measure of a fuels ability to resist detonation. But there is a limit. Go too high on the compression ratio and you may need more octane than is available. What happens with fuel that doesn’t have enough octane for the compression ratio you’re running is detonation. Detonation is a real power killer, and it’s not all that easy to detect. I’ve found the easiest way to detect it is with an EGT gauge. Detonation causes a drop in the EGT readings.
Comments, compliments, criticisms and questions always welcome.
For sure detonation is bad, it will cause lots of engine damage. We use a Diamond detonation meter on our Superflow dyno for big engines and does a pretty good job at early detection based on vibration. I have not rigged up this kind of meter on our small engine dyno as of yet, but been thinking about it however lately. Most of the engines we build have a low enough CR ratio that this is not an issue with detonation.
The stock Animal stroke is 2.204"
When stroking the Animal most people put an additional .233" stroke in the motor.
That gives you a total stroke of 2.437"
It can be measured in various ways but probably the simplest is to use a digital or dial caliper.
Given the questions you've asked, I'd advise you to either have an engine builder assemble this for you, and maybe one who will list out what he did for you....would be my advise.
It sounds like you have the parts, to build or have built for you, a very potent engine.
Carb and cam are critical components to your engine and should be installed, and the carb modified, by an experienced, professional builder.
Can i ask how old you guys are? Al and Paul
Let me guess. Over 60
Act your age.
Since when did it become your privilege to discourage any one from asking questions on this forum.
Give the kid a break. He wants to learn something.
It make no difference how old he or she is.
I'm glad he's asking questions. If he bothers you then just don't come on here.
What are you going to ask next? What race or nationality are you?