REFLECTOR: The definitive answer on octane and av-gas

[Jim Agnew]

I suspect that the dual ignition allowed for a retarded spark timing to allow
for the lower octane fuel.  It will work up to a point, however the engine will
produce less power.

In a car you can usually hear the knock when you are getting detonation however
in an aircraft it is usually too noisy to hear.  You might be able to adapt a
knock detector from an auto engine to detect it.

Jim

--- John Dibble <aminetech at bluefrog.com> wrote:

> When unleaded was introduced in the 70's, the disappearance of high
> octane leaded gas was an issue for BMW motorcycles, which had a high
> compression ratio.  One fix that was discussed and later adpoted by BMW
> was the dual ignition that allowed high compression engines to run on
> regular.  I wonder if this same principal applies to aircraft engines?
> Is there a definitive way to tell if your fuel octane is too low for
> your engine?
> 
> John
> 
> 
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=====
James F. Agnew
Jim_Agnew_2 at Yahoo.Com
Tampa, FL
Velocity 173 Elite Aircraft Completed & Flying