On 23 Nov 2005 06:49:09 -0800, "Denny" wrote:

At least one airplane is STC'd for E100, and reportedly the LyCon top
ends actually live far longer with this fuel.
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Just an aside::: IC engines live the longest on Propane... Just ask
any factory that converted it's gas powered fork trucks to propane...
So much for the , "ya gotta burn at least 25% 100LL to protect the
valves" crowd...

Yes, BUT ... the valve seats used with propane (and natural) had to be
made (or coated) with "stellite" in the earlier days to ot have wear
problems. I believe that the powdered metal used today in automobile
(and other(?)) valve seats acomplishes the same function.

Another interesting aside is that I installed a 10KW, propane powered,
220V AC generator with automatic transfer switching, because of our
frequent power outages here in the boonies... I can also run the engine
on natural gas with no changes, but the power output drops to 7KW if I
do... No natural gas lines in the middle of nowhere Michigan, so not
an issue for me, but an interesting fact I thought...

I thought I was going to be able to find good information via Google
to support you, but it isn't easy. Natural is mostly methane, and
that is lighter than propane but I cannot find better details ...
DARN.