On Sun, 23 Nov 2003 00:44:32 -0800, Jeff wrote:

I have played with leaning, did it as gami suggested, by running LOP I am down to
about 8-9 GPH which seems really low. I have an insight engine monitor which I use
when leaning. Leaning that much makes me nervous, I always feel like I will kill
the engine.

If your GAMI's are perfectly matched, you should kill the engine before
noting any roughness! But I don't think I would be nervous at those
settings. Besides, you could always enrichen and restart the engine.

I don't have a fuel flow meter, nor do I have GAMI's, but when I want to
fly economically, I will generally lean until all cylinders have shown a
one bar drop (from peak EGT) on my Insight GEM. This equates to 25-50°
LOP. At that setting, I'm generally burning 7-7.5 gph on my four cylinder
engine. That number is based on measuring how much fuel it takes to fill
the tank per unit time, not on a fuel flow meter.

If I had a fuel flow meter, I would probably be more aggressive about
adding back power.


the 12 gph is probably right about 50 degrees ROP, 13 will make it
about 100 degree's ROP.

At least for a Lycoming IO360, that's about the worst place to run it so
far as cylinder pressures and CHT's are concerned.

I am flying sunday morning to cedar city UT to practice some instrument approaches
with my new garmin 430 so will take the time to really mess with the leaning.

But I thought that by going lean, then increasing MP to get back lost power would
put more stress on the engine thus making it run at a higher output.

I believe your understanding is incorrect. My understanding is that one of
the advantages of running LOP is that you are decreasing the *rate* of burn
of the fuel. This, in turn, reduces *peak* cylinder pressure which is felt
to be an important factor in cylinder damage. By increasing the MP to get
back lost power , you must, of course, put "more stress on the engine" but
it is still *less* stress than you would get by running the same power ROP
by increasing the fuel flow using your mixture control.

Braley, the head of GAMI, reports that he routinely runs his TN'd Bonanza
at 85% power LOP.


I have a turbo, so I only fly at 65% power to keep the temps down since I dont have
an intercooler. All the other t-arrow owners I know said by flying at 75% power
they have cracked alot of cylinders. so the way I have been doing it was after
getting to cruise altitude, I would lean to about 12 gph which is consistant with
65% power.
But hell, I may have been doing it all wrong knowing me

BTW I think your mooney or the 201 has the same engine I have, I have to look and
see for sure. Its the TSIO-360-FB, 6 cylinder, fuel injected and rated at 215 HP in
some airplanes.


No, my Mooney has a Lycoming IO360A1A -- a four cylinder, fuel injected
engine. It is rated at 200hp.

GAMI has an engine management course that others have found valuable. In
addition, John Deakin has some articles on AVWEB (his column is called
Pelican Perch) which speak directly to the point you are wrestling with.

Ron (EPM) (N5843Q, Mooney M20E) (CP, ASEL, ASES, IA)