It's all about cylinder pressure. Pressure makes power.
There are a number of facters that influence pressure: static compression, altitude, cam design, etc. There are some other facters invoilved, like quench and chamber design. But they're very difficult to calculate. What you want is to get your cylinder pressure up around 190'ish psi. That's about the max pressure you can use with pump gas.
For example, my static compression is 13.2. But I can run all day on 91 octane pump gas.
http://www.wallaceracing.com/dynamic-cr.php