Fuel Prices For The July Pilgrimage

Matt Whiting wrote:
Ray Andraka wrote:

Matt Whiting wrote:



This is only true for engines that have very advanced ignition
timing, which isn't true for most GA piston engines, or engines with
very high compression ratios, again, not true for most GA piston
engines. Keep in mind that most were designed to run on 80 octane
avgas...


I don't disagree with the fact that in normal conditions, and a
normal engine, the power of an engine running 100LL or mogas should
be virtually the same.



Yes, I can't imagine many GA piston engines where this wouldn't be
the case. Maybe a turbocharged engine running very hot.

Matt


There are plenty of high compression GA piston engines that can't use
mogas because the octane requirement is too high. The majority of GA
engines are lower octane (something like 78% of the engines IIRC).
The majority of the hours flown in piston aircraft however is done by
the 21% of aircraft that have higher octane requirements than mogas
can offer, my 260 HP O-540-E4B5 included. It is a normally aspirated
6 cylinder engine, but with high enough compression that there is not
sufficient detonation margin with less than 96 octane fuel.


I'd like to see your source of these statistics.

Matt

I believe the numbers were from AOPA. I'd have to do some digging to
find them now. Those are the approximate numbers they were throwing
around about a year ago.