Have to agree with you Jay. I've had both my engines apart before and
after running Mogas for some time and both were much cleaner after
Mogas. Simply far less combustion chamber deposits, cleaner valves with
no measurable valve seat change. I notice no difference in the way my
0-360 Lyc runs but a big improvement in the way my 0-300D Cont runs.
One can forget about it until going cross country where no Mogas is
available and it starts running finaky again.
I figure if I'm too weak to lift a 5 gallon container of gas up onto
the wing then I'm too weak to fly and better get another pass time (or
let my wife do it. after all its her plane).
Jim

Jay Honeck wrote:
For example in their article on fuel, Aviation Consumer had a sidebar
on mogas saying it wasn't as good as advertised. They said several
shop owners told them that when they get engines or cylinders in for
work, they can immediately tell if the owner is running mogas by the
corroded camshafts and deposits on the valves and seats. These shop
owners claimed that the extra overhaul costs eliminate the mogas
savings, and attribute it to the "varying additives" used in mogas and
to the fact that most mogas sold doens't really meet the ASTM standards
dictated by the STC.

I read that article, and it is the closest thing to total bull**** I've
ever read on the subject. I can line up several shop owners who will
absolutely contradict the statements of those supposed "shop owners".


Nearly every INDEPENDENT shop owner I know (and that distinction seems
to be critical here) will testify that engines that have ran on
unleaded fuels are MUCH cleaner inside. They will tell you that they
can tell instantly upon teardown whether someone has been burning 100
LL in an engine that was designed to run on 80 octane avgas, simply by
the amount of crud inside.

100 LL has FOUR TIMES the amount of lead that my engine was designed to
run with. As a result, spark plugs foul with lead far easier, making
it necessary to aggressively lean the engine. Which, of course, in
turn leads to much higher exhaust gas temperatures, and unnecessary
wear and tear on the engine.

The ONLY time I've ever had engine trouble with Atlas' O-540 was on a
road trip where I was forced to run exclusively 100LL for days on end.
I fouled a cylinder so badly that BOTH spark plugs ceased firing,
requiring a quick return to the airport landing, (Not QUITE an
emergency, but close...)

I would run 87 octane unleaded car gas in my engine if it cost MORE
than 100LL. My engine simply runs better and cleaner on it, and I will
not run 100 LL unless I am forced to use it.
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"