2 quick questions

First of all in perfect working peak condition what should the compression be?, what did the fc come with from the factory and what compression do most rebuilds reach?

AND what would the "perfect" a/f ratio be for both n/a and turbo setups.

 

Easy. Take your compression ratio, such as your S5 engine. It would have a 9.7:1 compression ratio, meaning 9.7 bar. 1 Bar is 14.503774 pounds per square inch. Assuming you live at sea level, you can multiply your CR by 14.503774 (or just 14.5 because the other numbers wont make a difference). You get 140.68psi. I THINK that that number is on top of atmospheric pressure, so you can also add the atmospheric pressure of 14.5 to get about 165psi.

As for A/F ratios, every car is different. There are good numbers to go by (which you will find if you do a search about tuning A/F ratios) but they will need to be tweaked for every different setup. Do not go by what other people tell you, you need to go by what works best for your car, and how comfortable you are with those numbers (safety wise).

 

erm,,,, NO, port timing would change everything ^^^