Auster Juice
airborne_artist,
In my handling notes, the fuel is given as, "normally 73 octane, or unleaded fuel of any octane number up to 80".
Octane is only an anti-knock rating. So fuelling the aircraft on 100LL would probably allow the engine to be worked harder at a higher altitude than on 73 to 80 octane because the onset of knocking (detonation) would probably be delayed.
It would not provide 10 more b.h.p.
regards,
Broomstick.