Vaughn Mann wrote:

Hi Perry,
Don't know if this helps or not but when I fly my 6 (O-360) at 2200 rpm or
below for anything over thirty minutes at a time my plugs get pretty hefty
amounts of lead deposits!  Now that is leaned out of course to 25 deg. rich
of peak.
If I run at 2300 and above still leaned out, almost no deposits are found at
all.  The way it's been explained to me by the experts (Textron Lycoming)
etc, is it's all in the thermal dynamics of the engine operating at high
enough temperatures to completely activate the additive in the fuel that
actually helps the burning of the tetra ethel lead in 100LL.
If your indications of operating temperature are from oil and water
temperature only it could mean you may not be getting the real combustion
temperature (internal thermal dynamic) readings.  The additive they use in
100LL to trigger the more complete burning of tetra ethel lead (can't
remember the name of it) requires not just the higher temperatures but also
requires the higher velocity combustion/expulsion of a higher rpm that is
for the Lyc/Cont. type dinosaur anyway so they claim.
Many articles have been written about the use of TEL but most claim it was
intended for the raising of the octane and not so much for lubrication as
most of us would think.
Don't know if this adds more confusion or if it helps any at all,
Best regards, Vaughn.
PS, adding the oil to the fuel may deter or alter the intended
purpose/properties of the lead scavenging additive properties of the
additive too.  But remember, people running their rotaries at higher rpm
(via PRSU's and using 100LL) may not be affected by adding oil at all
though.

That is interesting Vaughn.  I haven't experienced lead fouling that I
can remember in the rental planes I flew. When your plugs get the lead
deposits at low rpm, do you notice a power loss or some other
indication? I wonder if the mechanical structure of the plugs aids/abets
this phenomeon?

--
Perry Mick
Custom Composite Props
mick@bridgingworlds.com
http://www.ductedfan.com

 
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