Badwater Bill wrote:

And, guess what, Corkman, the PSRU never did fail. Neither did any of
the other things I was worried about. In fact the old men kept on
making modifications and changes and a lot of the stuff that was on my
list at that time was incorporated into that airplane. And...just
because I was worried about many things I didn't understand as a pilot
at that time, doesn't mean that I was right in being so. It never
failed that I know about. In fact the PSRU turned out to be just
about the most bullet proof part of the thing. There were much bigger
issues like burning 100 octane fuel that caused more problems than the
damn PSRU ever caused.

I'm not an engine guru, so what is the issue with 100LL fuel? My
recollection when the auto industry converted from leaded fuel to
unleaded, that it was the lack of lead that caused burned valves and
required different valves and valve seats. I do understand that higher
octane means a slower flame front. My guess is that the higher octane
in 100LL is keeping the combustion event ongoing long enough that the
exhaust valve opens while the fire is still pretty hot. Is this what
causes the valve problems? It can't be lack of lead as 100LL still has
lots, even with the "low lead" description.


Matt