Why is ther no formula to figure out port volume?

There is a formula and it works off of connecting rod length, and piston speed. The formula is based off of CI in the cut down version and will dictate the valve size also. It's very lengthy so I'm not going to even start to type all this out here, it would be easier for you to give me the info and let me put it in for you as I have it downloaded to a saftey keyed program.