"flynrider via AviationKB.com" u32749@uwe wrote in message
news:70fea2213e94e@uwe...
Matt Barrow wrote:
What's really strange is all those new 4 seaters are designed with
engine requiring 100LL, instead of 91/96.

It part of a big bore engine.

It has nothing to do with the bore, and everything to do with the
compression ratio.

Yes! My bad!

And what is the threshold for compression ratio?

Why does my current 7.5:1 CR still need 100LL when my older 8.5:1 did as
well?