Mogas
Posted: Sat Feb 18, 2012 9:27 am
It might be interesting to hear more about Angus's valve problems
because I believe that leaded fuel is about the worst thing you can do
to valve guides. Perhaps the larger radial engines have some
peculiarities that I'm not familiar with.
Any lead deposits on valve stems are extremely abrasive. Last time I
paid attention to this, the Cessna pilots association claimed it would
save more the US$10. per hour maintenance to use mogas in single engine
Cessnas.
Lead is a cheap way to increase octane and it definately lubricates the
valve sealing surface but it is a bad thing for valve guides and living
organisms as far as I know. Personally I'd try hard to run more than 75%
mogas (if available without alcohol in it) through one of these small
Lycosaurs and would ignore what mixture was in the tanks unless flying
high and or in hot conditions. I think even 80/87 was way more lead than
optimum for these engines let alone 100LL.
Liquid cooled engines do run dramatically cooler valve guide
temperatures but I don't recall anything about that in regards to leaded
fuel vs unleaded.
Ken
Mike Kimball wrote:
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because I believe that leaded fuel is about the worst thing you can do
to valve guides. Perhaps the larger radial engines have some
peculiarities that I'm not familiar with.
Any lead deposits on valve stems are extremely abrasive. Last time I
paid attention to this, the Cessna pilots association claimed it would
save more the US$10. per hour maintenance to use mogas in single engine
Cessnas.
Lead is a cheap way to increase octane and it definately lubricates the
valve sealing surface but it is a bad thing for valve guides and living
organisms as far as I know. Personally I'd try hard to run more than 75%
mogas (if available without alcohol in it) through one of these small
Lycosaurs and would ignore what mixture was in the tanks unless flying
high and or in hot conditions. I think even 80/87 was way more lead than
optimum for these engines let alone 100LL.
Liquid cooled engines do run dramatically cooler valve guide
temperatures but I don't recall anything about that in regards to leaded
fuel vs unleaded.
Ken
Mike Kimball wrote:
workingWhat's the difference between automobile and airplane valve guides? How
come valve guide lubrication isn't a problem with unleaded in cars?
Also, is there any reason why 100LL and MOGAS shouldn't be mixed? (Other
than unknown octane rating and vapor pressure and the usual rubber parts
incompatibility with one type or the other.)
Mike Kimball
SR #044
-----Original Message-----
From: mike.davis@dcsol.com [mailto:mike.davis@dcsol.com]On Behalf Of
Angus McKenzie
Sent: Thursday, August 26, 2004 7:06 AM
To: rebel-builders@dcsol.com
Subject: Re: Mogas in the M-14P?
Just my opinion BUT each time I've had an ag-plane engine quit while
it was valve-guide/mo-gas issues,I personally would not put car gas in an
airplane unless it was an emergency........Angus
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