On Thu, 01 Jul 2004 21:44:26 -0500, Mike Rhodes
wrote:

But if the engine
is below 75% power then what difference does it make what mixture is
in any particular cylinder? If I need economy I go to roughness. If
I need speed then I enrichen it to gain power. And I would expect
more wear-and-tear at the higher power of richer mixture settings --
_IF_ I get higher power at richer mixture and don't begin to waste
fuel. I can monitor my airspeed to see where an another optimum
mixture setting exists.

I think you've got it, at least as I understand it anyway. My only
concern was that if you are using a high power setting at below 8,000
feet, leaning to roughness and then richening to smooth operation
might put you into the red zone, that zone as defined in Deakin's
graph's, which can cause high cylinderhead temperatures.

I don't know how much you read through the "Mixture Magic" column, but
there's that one, plus four others that go into minute detail on
exactly what happens inside the engine on the Ground, Takeoff/Climb,
Cruise and Descent.

Deakin wrote columns for AVWeb, he wasn't writing NACA white papers.
His "Mixture Magic" column included many graphs from Pratt and Whitney
as well as Lycoming, Continental and actual test stand results from
the GAMI shops. At one point, they boosted turbo pressure to
demonstrate graphically what the onset of detonation looked like on
the graph. Deakin remarked that the engine definately did not sound
happy. This information was represented on a color coded graph. You
could see the traces of detonation represented by squiggly lines on
the pressure rise.

In my opinion, if the subject interests you, you might want to
download all five articles and print them out to a color printer so
that you can read them at your leisure. I also enlarged those graphs
that allowed you to do so and printed them out seperately so I could
refer to them from the text. Otherwise the graphs printed out a bit
small.

It's my opinion that all the information you need to safely and
economically operate your engine is there in those five columns. It
isn't all conversational text, every single claim he makes is backed
up by graphs and/or readouts and pictures.

At one point he casually remarked that he wished he had the time to do
timed climbs leaning as he climbed to plot the savings in gas and time
to climb. One of his readers hopped into his own airplane which was
equipped with a JPI EGT analyzer and flew out from under the LA Class
B space and then made two climbs to 10,000 feet carefully leaning as
he climbed during one climb and leaving it rich for the other. Then
he e-mailed Deakin the electronically recorded information and Deakin
formatted it into Excel and presented the results in his next column.

I have a friend who has just became the owner of a V tail Bonanza,
which is what Deakin flies, only Deakin's is turbocharged. He has
been flying for a number of years and just cannot bring himself to run
it LOP . . . yet. He understands the concept, but was a race driver
and builder and engine assembler in his youth, and recalls what
happened to his engines if they ran lean. As Deakin mentions though,
we aren't talking about leaning during takeoff power operation. We
will be trying out LOP operation in the next few weeks to see if the
engine will tolerate it without running rough. He does not have GAMI
injectors.

Corky Scott