I remeber seing maximum cranking cylinderpressure numbers from mainly Joe Sherman in Hot Rod Magazine. I don't know if anyone has any opinions/experieance/theory on this subject when it comes to aircooled motors. I think that this could be a way to develop the heat and pinging controll in our little motors so I think it needs to be addressed. I notice that a lot of the motors that were tested in the enginge builder challange had high compression ratios and there must have been a delopment in this area over the last years. I remember when I bumped the CR to more then 11:1 and ran the motor on the street. No one belived it was possible. That was just 8 years ago and the Blue handbooks of that time stating no more than 8:1 ruled.
It depends on what fuel you have and what cam size. With our german shell V power you can run more than 11:1
Udo