[chevyIIpost]

One major factors effecting compression is the duration of your cam. It will directly effect your DCR(dynamic compression ratio) or accual pumping cylinder preasure not the mathamatically calculated compression ratio of say 11:1. The LS engines are the perfect example of efficient cylinder heads/combustion camber design that allows high compression with a short duration cam. This is a difficult balancing act to duplicate even for the best engine builders with all the knowlege of how each component effects this balance. Then even the vehicle and something like gearing and how the motor is loaded will also play into this package. When you start pushing the max limit of any SYSTEM or combination of parts the weak link or marginal item will show itself quickly. Pushing your compression ratio will require EVERYTHING else to be spot on or problems will show themselves quickly. But isn't that what Performance Hot Rods are basically all about. To take as many of the OEM compromises out of your car and improve it to meet your specific needs and not Joe Commuters.

You mentioned "not Aluminum"? The thermal properties of Aluminum heads will make the engine more tolerant of higher compresion by pulling heat out of the combustion chamber during daily driving or part throttle operation. This is a good thing if you are pushing your compression. The very basic rule of thumb is to reduce your mechanical or calculated compression a 1/2 point when running cast iron heads.