Comp. Ratio ?s
 

I was figuring the Comp. ratio for a bracket engine. I have these question for you smart math guys.
1. when figuring the volume of the cylinder, shouldn't you add for valve notches and subtract for the dome when the piston is at BDC?

2. since the valve notches are in the cylinder at both BDC and TDC, then they should be added into to the total volume, right? or because they are there at BDC and TDC and thus cancel out.

3. since the dome is displacing at BDC, but not in the cylinder at TDC, how do you deal with that?

anything else you want to add, please do.
Thanks Rod in AZ

Re: Comp. Ratio ?s
 

Wallace Racing.com has some good calculators for this.

Re: Comp. Ratio ?s
 

Hi,

It's the large total volume (BDC) forced into the small volume (TDC).....

The reliefs and the domes make up the total volume at BDC and TDC after that it's just division to come up with the CR...

Subtract the reliefs and add the dome to a flat top for the correct number and don't forget the gasket thickness and bore diameter of the gasket..

Bob

Re: Comp. Ratio ?s
 

The Eagle rod web site has a C/R feature that is fun to play with.