From: William Wilson [mailto:fluffysheap@gmail.com]
Subject: Re: [LML] Re: L-IV Choice of Engine
. . . As a practical matter, many or most piston engine aircraft owners do not run lean of peak to prolong the life of their engine .  . . .
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Might be a word missing here.  Should read  ... do not run lean of peak ONLY to prolong the life of their engine...  (That is true because the other reason is fuel efficiency.)

Virtually every study in the past 15+ years has demonstrated that slightly RoP is the worst possible mixture from a detonation standpoint whereas LoP always yields a safer combustion, lower fuel consumption, cleaner plugs, and a host of other aspects that prolong the life of the engine.  A recent survey on-line showed about a 50:50 split of pilots running each condition, but I expect that many/most running RoP are not instrumented well enough to know if they are indeed LoP on all cylinders.  Running really rich is safer than guestimating that all cylinders are LoP when actually one or more are in the critical 50F deg. RoP.

Robert M. Simon
ES-P N301ES