Leaning / step climbing?

(Rick Durden) wrote in message om...
John,

Specifically, you should not be leaning if your engine in making 75%
power or better.

Not necessarily so. It is perfectly okay to lean at 75% power, the
manual for your airplane has a fuel burn for 75% with lean mixture.
In fact, if you don't lean when operating at 75% with that Lycoming,
you will significantly reduce your range and endurance and possibly
foul the plugs. www.gami.com has a good discussion of leaning and
what's going on during combustion. It may be perfectly okay to lean
at power settings above 75%.


OK, perhaps I didn't include enough information. For the Lycoming
engines found in most common Cessnas & Pipers, Lycoming manuals
usually have caution against leaning above 75% power. Perhaps I
should have reworded my comment above to read "76%" or "75.5%".

I've seen exhaust valves from engines that were run at high power
settings while leaned to just below peak. They were not pretty (and
would not hold compression).

John Galban=====N4BQ (PA28-180)

"John Galban" wrote in message
om...
(Rick Durden) wrote in message
om...
John,

Specifically, you should not be leaning if your engine in making 75%
power or better.

Not necessarily so. It is perfectly okay to lean at 75% power, the
manual for your airplane has a fuel burn for 75% with lean mixture.
In fact, if you don't lean when operating at 75% with that Lycoming,
you will significantly reduce your range and endurance and possibly
foul the plugs. www.gami.com has a good discussion of leaning and
what's going on during combustion. It may be perfectly okay to lean
at power settings above 75%.


OK, perhaps I didn't include enough information. For the Lycoming
engines found in most common Cessnas & Pipers, Lycoming manuals
usually have caution against leaning above 75% power. Perhaps I
should have reworded my comment above to read "76%" or "75.5%".

http://www.avweb.com/news/columns/186015-1.html

November 9, 2003
Pelican's Perch #75:
Those Dreadful POHs (Part 1)

Everything your POH says is correct, and anything it doesn't say you can do,
you can't, right? Did you really think John Deakin -- AVweb's favorite
contrarian -- could let that kind of gross generality continue unquestioned?
I've seen exhaust valves from engines that were run at high power
settings while leaned to just below peak. They were not pretty (and
would not hold compression).

http://www.avweb.com/news/columns/183094-1.html
March 2, 2003
Pelican's Perch #66
Where Should I Run My Engine?
(Part 4 -- Descent)

After a short discussion about whether running engines the factory way or
the skydiving way will hurt or help engines, AVweb's John Deakin settles in
for the descent. And, yes, there are more old wives tales to be debunked,
and better control settings to use.
-----------------------------------------
http://www.avweb.com/news/columns/182583-1.html
February 2, 2003
Pelican's Perch #65
Where Should I Run My Engine?
(Part 3 -- Cruise)

Cruise -- Time to sit back and enjoy the flight. But wait ... did you leave
the mixture set where it was during the climb? Or do you just set it where
it
------------------------------------------------

Picture, charts, loads of data... Deakin makes some very strong points that
much of what has been presented in POH's over the last several (read: 30 or
more) years has been downright BOGUS.

Tom
--
"What's our vector, Victor?"

(John Galban) writes:

I've seen exhaust valves from engines that were run at high power
settings while leaned to just below peak. They were not pretty (and
would not hold compression).

Was it heat damage? I'd imagine that they'd be even worse if they
were leaned to just above peak.


All the best,


David

David Megginson wrote in message ...
(John Galban) writes:

I've seen exhaust valves from engines that were run at high power
settings while leaned to just below peak. They were not pretty (and
would not hold compression).

Was it heat damage? I'd imagine that they'd be even worse if they
were leaned to just above peak.


Yes, it was heat damage. The plane in routinely ran leaned at about
85% power for about 150 hrs. Two of the 4 exhaust valves were
toasted.

On a well instrumented engine you could probably get away with
leaning at higher power settings. I think the reason Lyc. puts the
limit at 75% is that the average spam can does not have enough
instrumentation to keep all cylinders in the green during all types of
operation.

John Galban=====N4BQ (PA28-180)

Just above peak?

Paul

"David Megginson" wrote in message
...
Was it heat damage? I'd imagine that they'd be even worse if they
were leaned to just above peak.

true

"Thomas Borchert" wrote in message
...
Btiz,

Some will argue it is not needed to lean below 3000MSL..


Uh, only those clinging to one of the more stupid OWTs (Old Wive's
Tale).

--
Thomas Borchert (EDDH)