Avgas 100LL actually 108RON+.
While I wish it was the case (and I do!)
I sort of doubt it, Greg. The guys who
used to fll their tanks with this stuff
years ago complained of running hot
along with burnt valves over time, and
a tendency to "ping" under heavy load.
Retarding the timing a couple of degrees
cured all the above! That's when I got
curious and made a couple of calls to
the "technical" people who supplied avgas
to the FBO (flight school, air charter) I flew for at the time, and was
advised about the different burn characteristics
of avgas vs automobile gas due to different formulas for different
applications. Aviation/Auto fuels of
similiar octanes have a different burn
rate in same application. Effectively,
you could say Avgas in same (automotive) application burns "sooner" or
"faster" than
an automotive fuel of similiar (but less) octane would.
Made sense to me why retarding the
timing was required of the higher advertised aviation octane vs
automotive
hi-test of a slightly lower advertised octane. The octanes cannot be
thought
of on an equal "1 to 1" basis as the gasolines in question are simply
not the "same". So I chose to spend the "extra"
bucks on CAM2 and "mix" it to run my
11.0-1 Spridget on a 100 octane mix.
Timed car accordingly and began using
full strength 100LL avgas only, shortly
thereafter. Engine started pinging almost
immediately. This convinced me the
experts knew their stuff. Haven't considered available avgas since.
Understand I am the "messenger" here,
and not the "technical expert", though my
little experiment indicated I was getting
valid information from the gasoline company technical types I spoke
with.
Cap'n. Bob
'61 :{)
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