I know that honda produces great combustion chamber designs and some honda's are running around with 11.0 compression ratios. But why is it when I mention anything higher than a 9.5CR for my uncles Ford 302 he says he needs 100 octane?

I know how octane ratings work and I understand that. But is there that big of a difference in the combustion chambers that we can run 11.0 on 93 octane but he's stuck at the lower.