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This calculator, like most, doesn't account for piston top OD and ring depth. It also makes an assumption on head gasket bore diameter that's incorrect. Close but no cigar.
I got 10.9:1 for the LQ9 guy on the free calculator, but i guess that little bit can make the difference on a built race motor.
If accuracy isn't a concern than why even calculate it? There is only one correct way to calculate compression ratio and as long as the parameters are correct one can't argue with the math.
I'm personally debating picking up some 241s dirt cheap and having them ported. 11:1 may be too much compression for me. The 67cc 241s would be more friendly