[radialtireking]

Every combo is going to be differant. Cyl. head design and cam profile play a big part in it. Weight of the car, gearing, stall speed also play a role. Another key to running high compression on pump gas is keeping coolant temp down. The closer you get to the limit the better you need to be at tuning. Correct fuel and timing curves are a must. The above numbers of 10-1 with iron heads and 10.5-1 with aluminum are a good safe number to go by. What are your intentions with the car? A point of compression may not gain enough power to warrent the potential tuning problem or the need for better fuel. Will this engine be N/A or planning on a power adder? I think knowing the goals of the car will help lead you in the direction you need to go.