Why is LOP (lean of peak) controversial?

"Dan Luke" wrote in message
...

"Andrew Gideon" wrote:


One of those two people tells a story of someone that bought gami
injectors, ran LOP, and then cooked four of six cylinders.


Another example of how a little knowledge is a dangerous thing.

*Improper* LOP operating technique can harm cylinders, even cause
catastrophic failure by detonation.

As can *proper* ROP operating techniques...particularly the 50ROP as
recommended by some POH's.

The biggest problem is getting LOP, then enriching "just to be on the safe
side", usually right into the worst possible operating range.

"Peter R." wrote in message
...
"Peter R." wrote:

In my case, my engine's cylinder head temperatures rarely get above 310
degrees F and most times operate in the 285 degree F range during cruise
flight. The times they do climb to 310 or 320 degrees F is when I am
climbing to altitude on a very hot day.

I should have included that 380 degrees F is considered the absolute top
end of the safe temperature curve, at least according to Tornado Alley
Turbo and GAMI, both of whom have done extensive testing of LOP
operations.

Even on a hot day at higher density altitude (and effectively less ram air
cooling), 320 degrees F is the highest I have seen my cylinder head
temperatures reach.

What % of power are you using? I'm usually around 360-370, but I'm running
70-75%.

Matt Barrow wrote:

What % of power are you using? I'm usually around 360-370, but I'm running
70-75%.

I also cruise around 75% of the IO-520's 285 hp.

--
Peter

I ussed to be timid on the "red knob" easing it out until I hit peak EGT
and then kept going until I would get 20 degrees or more LOP and then
stay there. That technique though probably OK, kept me in the red box a
little longer than I preferred.

My current technique is to get to cruising altitude and then do "the big
pull" on the mixuture until a definite power loss is noticed. I know
know I am way on the LOP side so I come in a tad to smooth it out and
note the EGT and CYL head temps. Both are nice and cool ( CYL 400 &
EGT 1400). I'm usually cruising at 150 + KIAS nad 9 GPH. Gotta love
those Mooney's.

Jon Kraus
'79 Mooney 201
4443H @ UMP

Dan Luke wrote:
"Andrew Gideon" wrote:


One of those two people tells a story of someone that bought gami
injectors, ran LOP, and then cooked four of six cylinders.



Another example of how a little knowledge is a dangerous thing.

*Improper* LOP operating technique can harm cylinders, even cause
catastrophic failure by detonation.

Andrew,

So...what am I missing?


The inertia of the pilot population, myths, misinformation, engine
manufacturer's law departments - all factors. "Show me the numbers" is
the old trick to silence the LOP opponents. They can't.

I take it you are familiar with John Deakin's columns on the topic and
engine management in general at avweb.com?

--
Thomas Borchert (EDDH)

: I take it you are familiar with John Deakin's columns on the topic and
: engine management in general at avweb.com?

These articles basically say:

- LOP done improperly *WILL* damage engines. Only at 75% or less can it be done
safely.
- Absolute EGT doesn't matter... CHT primarily controls detonation margin, top end
longevity, and exhaust valve temperatures. (Lycoming and Cont have too high of
redlines... 400 CHT is as high as should be periodically seen... 375 max continuous)
- ANY leaks in ANY valves are unacceptable and will cause damage, LOP or not.
- ROP provides the most power for a single "power setting" (i.e. MP+RPM setting...
*actual* power setting also includes the mixture). Thus marketing likes ROP since it
makes the plane go faster on paper.

I use these articles (and Lycomings recommendations) to operate my 180 hp
Lycoming O-360. It's carb'd so LOP doesn't quite get there. Below 75%, I can do
anything I want with the mixture so long as CHT stays cool enough. I typically
consider 65% power and 350 CHT my maximums. At those settings, I can lean to
where there is a noticable power loss, but before it's rough, and 8-8.5 gph.

-Cory

--

************************************************** ***********************
* Cory Papenfuss, Ph.D., PPSEL-IA *
* Electrical Engineering *
* Virginia Polytechnic Institute and State University *
************************************************** ***********************

"Peter R." wrote in message
...
Matt Barrow wrote:

What % of power are you using? I'm usually around 360-370, but I'm
running
70-75%.

I also cruise around 75% of the IO-520's 285 hp.

What altitude? FF?

Matt Barrow wrote:

"Peter R." wrote in message
...
Matt Barrow wrote:

What % of power are you using? I'm usually around 360-370, but I'm
running
70-75%.

I also cruise around 75% of the IO-520's 285 hp.

What altitude? FF?

In summer temperatures at 12,000-15,000 feet I get about 187-190 kts TAS at
about 15 gph. In the winter, I see 175-180 kts TAS and 16.5 gph or so.

--
Peter

One thing no one has mentioned is LOP may not be possible with
carbureted engines. The flows to each cylinder just aren't consistent
enough to make it work. Also you really need CHT and EGT guage on each
cylinder to do it right. The problem with LOP, isn't running LOP, its
that you are running peak and THINKING you are running LOP. The same
could be said of running rich of peak too. Running AT peak is really
only a problem at higher power settings. So most of this LOP stuff is
really for turbocharged fuel injected engines. I said MOST. Some people
with just fuel injection use LOP and a FEW at least claim to use it
with carburetion.

LOP works, but I think you have to really know what you are doing and
have the right equipment. But if you are running at 65% power or below,
it doesn't hurt to try it, no matter what sort of equipment you have
(unless of course you dont even have a mixture knob :-))

Thomas Borchert wrote:
Andrew,

So...what am I missing?


The inertia of the pilot population, myths, misinformation, engine
manufacturer's law departments - all factors. "Show me the numbers" is
the old trick to silence the LOP opponents. They can't.

I take it you are familiar with John Deakin's columns on the topic and
engine management in general at avweb.com?

--
Thomas Borchert (EDDH)

On 09/26/06 15:38, Andrew Gideon wrote:
I'm not asking about LOP itself, but why it's so "hot" snicker a topic.
It would seem to be a simple thing to me: the cylinders run at decent
temperatures LOP or they do not. What else is there?

I know at least one person in person, and others from their postings, that
are getting success running LOP. I also know at least two persons that
think that LOP is some myth that kills cylinders. One of those two people
tells a story of someone that bought gami injectors, ran LOP, and then
cooked four of six cylinders.

What I don't understand - and what that person hasn't answered, BTW,
perhaps because he doesn't know - is why that person that "cooked" four
cylinders would have failed to see a problem immediately on his CHT probes.

So...what am I missing?

- Andrew


How's this for timing. Mike Busch at AVWeb just wrote a new "The Savvy Aviator"
column on this very topic. Have a look:

http://www.avweb.com/news/savvyaviator/193242-1.html



--
Mark Hansen, PP-ASEL, Instrument Airplane
Cal Aggie Flying Farmers
Sacramento, CA