page 45 - American Bonanza Society

Currents By Lew Gage
LOP with an E225
In the March 2013 ABS Magazine I wrote about installation of the new
Insight G1 engine analyzer in place of the original GEM EGT instrument
in my G35. I have run the airplane enough that I am able to offer some
follow-on information on this comparatively superior system. There was
no question in my mind in 1987 that the GEM system was a huge advance in
aircraft engine monitoring. Over the years that original unit provided useful
information and enhanced my operation of the airplane, resulting in about
10 percent fuel savings and including a second readout of CHT.
During the time I was using the
old GEM system, there were many
advances in the processing of information
displayed to the pilot in
these engine monitoring systems
manufactured by Insight and other
brands. Also during that time, our
friends at GAMI started experimenting
to improve engine operation and
efficiency. They succeeded in doing
so by obtaining STC authorization and
PMA approval to manufacture and
install balanced injector nozzles on
the several fuel injected engine models
they were working with. The net result
were engines that ran cooler, burned
less fuel, and probably had less wear
and tear on the cylinders.
I received many inquiries from
ABS members about whether this
really worked and could it be used
on the E engine-powered V tails. My
reply was yes, it would work in fuel
injected engines if you had a set of
the GAMI injector nozzles, studied
the GAMI operation procedure, and
understood it and faithfully followed
those procedures while operating
the airplane. However, with the
PS-5C carbureted engines I did not
recommend attempting lean of peak
EGT (LOP) operation due to the uneven
spread of mixture distribution among
the cylinders. A high percentage of
these old Bonanzas have no really
accurate EGT/CHT instrumentation.
The factory installed gauges were
okay for very basic operation of the
engine, but even with installation of
the GEM or similar system there just
was not a display of what was going
on during the mixture control process
that could monitor the result of pulling
or pushing the “red knob” beyond
the Flight Manual or Pilot’s Operating
Handbook recommendations.
I did find with the GEM system
that the mixture distribution could
be improved a considerable amount
by a simple reduction of about 1/2 inch
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22 AMERICAN BONANZA SOCIETY MAY 2013