tried LOP for the first time - have some questions

[201er]

Ok, I'm a bit of a newb so bear with me on my dumb question about this. If Lycoming says peak operation is recommended up to 75% power (and peak is the point of highest ICP and lowest detonation margin), then how can it possibly do any more harm to be on the leaner side of it?

[jetdriven]

Because they say so!  Their position is ludicrous'

[John Pleisse]

Quote: jetdriven

Because they say so!  Their position is ludicrous'

[Shadrach]

Quote: 201er

Ok, I'm a bit of a newb so bear with me on my dumb question about this. If Lycoming says peak operation is recommended up to 75% power (and peak is the point of highest ICP and lowest detonation margin), then how can it possibly do any more harm to be on the leaner side of it?

[201er]

Quote: Shadrach

Highest ICP and CHT occurs at some point ~40 LOP. 

[Gone]

Quote: Shadrach

Highest ICP and CHT occurs at some point ~40 LOP, if you're speaking about a single cylinder 20-25 dergree fixed timing engine. Anything leaner or richer than that will increase detonation margins. Peak has higher detonation margins than 50 ROP. 

[scottfromiowa]

There seems to be nothing wrong with flying by the POH...or flying LOP with a four or six probe cylinder temp/exhaust gas monitor.  Both are documented to reach TBO.  One is faster...one saves money.  Wax on wax off.  Seems there is displacement from Lycoming to a MooneySpace member by other members.  I'm enjoying the trial...oops, got to go my popcorn is done.

[Shadrach]

Sorry, I don't quite follow. How can CHTs be highest LOP? Not even just looking at factory charts, I've seen them go way down flying LOP. This doesn't make sense.

[carusoam]

Edgar and those familiar with the red box graph or APS course,

This graph is not engine specific right?

It applies to 4cyl IO-360 as well as 6 cyl IO-550?

I am looking to use it as a tool, but want to make sure that it applies first.

Best regards,

 

-a-

[Gone]

Quote: carusoam

Edgar and those familiar with the red box graph or APS course,

This graph is not engine specific right?

It applies to 4cyl IO-360 as well as 6 cyl IO-550?

I am looking to use it as a tool, but want to make sure that it applies first.

Best regards,

 

-a-

[carusoam]

Ned,

There are two other things that I get from this graph...

(1) no red box above 8,500' for NA engines.

(2) can avoid red box by staying 25 deg F LOP from 4,500’ and above

Just want to be sure before I commit.....

Note: I am using the IO 550, POH recommends 50 deg F LOP for all alts.  This much LOP is harder to achieve at higher alts.

 

Best regards,

-a-

[201er]

Quote: Shadrach

Good catch guys...I meant 40ROP.  I had a late night without much sleep.  As I said in a number of preceding posts, 40 ROP is the area with lowest DMs. I edited my last post.

[Gone]

Quote: carusoam

Ned,

There are two other things that I get from this graph...

(1) no red box above 8,500' for NA engines.

(2) can avoid red box by staying 25 deg F LOP from 4,500’ and above

Just want to be sure before I commit.....

Note: I am using the IO 550, POH recommends 50 deg F LOP for all alts.  This much LOP is harder to achieve at higher alts.

 

Best regards,

-a-

[Gone]

Quote: carusoam

Ned,

There are two other things that I get from this graph...

(1) no red box above 8,500' for NA engines.

(2) can avoid red box by staying 25 deg F LOP from 4,500’ and above

Just want to be sure before I commit.....

Note: I am using the IO 550, POH recommends 50 deg F LOP for all alts.  This much LOP is harder to achieve at higher alts.

 

Best regards,

-a-

[Shadrach]

Quote: carusoam

Edgar and those familiar with the red box graph or APS course,

This graph is not engine specific right?

It applies to 4cyl IO-360 as well as 6 cyl IO-550?

I am looking to use it as a tool, but want to make sure that it applies first.

Best regards,

 

-a-

[Shadrach]

Quote: 201er

If this is the case and operations at peak are recommended (and there is NO limitation regarding operation between peak and 100ROP either) up to 75% power, how can you possible screw up by being even cooler than that by leaning LOP? I just cannot comprehend how accurately leaning LOP with an engine monitor could in any way be worse than leaning 50ROP by any other primitive method???

If the pilot ends up a little leaner, no harm. If a little richer, then just closer to peak which is still acceptable. Where is the problem? What is so risky about this? What is so difficult about this that only the elite 2% of pilots can handle this? If we can handle flying, navigation, communication, safety, etc all while flying a complex airplane, what's so impossible about setting the mixture on the lean side of peak instead of on the rich side? What's so special or difficult about the lean side of peak that a busy pilot would have more trouble setting it there than the rich side? I feel like I'm missing something because it sounds too simple to be that way. What's the catch?

[jetdriven]

I would say that I agree with Ross. We could lean to 10 LOP pretty much from 4000' on up, and peak above 7000 but we just changed our magneto timing from 20 to 25 degrees and now we can do more like 25-50 LOP below 3k, and 15-20 LOP above 4k. CHT are higher and EGT are lower.  The airplane also indicated 187 MPH at WOT sea level from the 183 it would do previoulsly.

[jetdriven]

Even according to this graph there is no red box above 8500', I dont think you need to run 50 LOP at higher altitudes. CHT will tell what it likes.

Quote: carusoam

Ned,

There are two other things that I get from this graph...

(1) no red box above 8,500' for NA engines.

(2) can avoid red box by staying 25 deg F LOP from 4,500’ and above

Just want to be sure before I commit.....

Note: I am using the IO 550, POH recommends 50 deg F LOP for all alts.  This much LOP is harder to achieve at higher alts.

 

Best regards,

-a-

[jetdriven]

Still waiting for Lycoming's official position today.  I know their sales rep's position.  I know at Oshkosh they said know that people can operate LOP and they are developing a program, and to stay tuned. They should call Braly, but they are primarily Continental guys.

5$ avgas will get you thinking about LOP.  Ignore MP and RPM.  Set power with fuel flow.  What a concept.

Quote: jetdriven

[201er]

Quote: Shadrach

Now you are getting the frustration that most of us who understand combustion science feel about the illogical stance taken by Lycoming...

[Shadrach]

Quote: 201er

I don't feel smart enough to be in the 2% so I keep feeling like there's something I don't know which holds me back. But every time I consult pilots or read about it, seems simple enough to me. Then Lycoming, mechanic, or pilot confuse me again by telling me how bad it is but I don't understand why exactly it's bad.

Here's another thing I don't understand. If LOP operation is in fact better for the engine, then why doesn't Lycoming actually recommend it for warranty engines instead? Wouldn't it mean better profits for them by fewer claims? I don't think the people at Lycoming are stupid, so it worries me a bit that there is some catch to LOP operations. I'd totally like to hear from the anti-LOP guys cause I still don't fully understand the arguments against LOP in cruise in NA Lycoming?

[201er]

Sorry to beat this topic to death but I still have questions left unanswered. I understand that for a turbo or putting power back in things can get a little complicated, but LOP strictly as a leaning technique for a normally aspirated IO360...

Lycoming (as well as mechs and other pilots I've talked to) say that leaning LOP is difficult for the average pilot and especially under heavy workload. Is it really THAT hard or is the average pilot a really sad excuse for an aviator? Except for holding two buttons to switch the engine monitor into LOP mode for leaning, it really seems no different than leaning ROP except the bars go the other way.

Lycoming's position summed up is:

Operating an engine “on the edge” is possible provided the pilot
is extremely precise, has good instrumentation, and monitors the
engine condition full time. For 98% of the pilots, it is an invitation
to potential trouble. It only takes one brief episode of
mismanagement to incur deep internal damage that will cost
money later.

A) How is LOP on the edge? The edge of what? Peak? Peak is recommended. The too lean edge? How does that do harm?
Why does LOP have to be extremely precise? How does it require being precise any more than "50 ROP"?
C) How does ROP not require good instrumentation?
D) Why is it so critical to monitor the engine condition full time when LOP? I honestly don't understand the significance of this one. Set the mixture in cruise. As long as power, altitude, or air temp don't change, the mixture doesn't need to be touched either. During longer flights I would decide to relean the engine after time to find peak and set again and just return to the same place confirming it was right all along. LOP ends up being cooler so I'd almost think ROP requires closer monitoring of temps than LOP. What am I missing here? Why does it require "full time" monitoring?
E) What kind of trouble does LOP invite that Peak or ROP does not?
F) What is a "brief episode of mismanagement?" Going too lean would just make the engine start to sputter but no harm. Going too rich would bring you closer to peak and raise temps but no more than peak or ROP. So it really doesn't make sense to me how LOP can be more difficult or more damaging than ROP?
G) What kind of deep internal damage and how does LOP lead to it?

Every time I start to feel like I am understanding the theory and process of operating LOP, I am reminded by skeptics of how difficult/dangerous LOP is but I really can't understand how or why. Can anyone justify Lycoming positions for each of my points? Can anyone explain to what special care is needed for LOP that I may have been missing?

[Parker_Woodruff]

A) Exactly.  Anything with all cyls LOP is better than 50 ROP.

Just precise enough to make sure all cylinders are sufficiently LOP to reap the benefits.

C) I guess you're already doing your engine a minor disservice while ROP, so the instrumentation is really to make sure you're helping all your cyls by running LOP

D) It's not that difficult, just as you suspect.  Set your power based on a fuel flow.  For you, 9 gph is apprx 68% power when LOP.  10 GPH is approx 75%

E) Not really anything if all your cyls are sufficiently LOP.

F) The problem is that Lycoming tells you to operate on a normal basis exactly where this "mismanagement" would occur.

G) None if you are operating sufficiently LOP for the desired power setting.

[scottfromiowa]

Quote: 201er

Sorry to beat this topic to death but I still have questions left unanswered. I understand that for a turbo or putting power back in things can get a little complicated, but LOP strictly as a leaning technique for a normally aspirated IO360...

Lycoming (as well as mechs and other pilots I've talked to) say that leaning LOP is difficult for the average pilot and especially under heavy workload. Is it really THAT hard or is the average pilot a really sad excuse for an aviator? Except for holding two buttons to switch the engine monitor into LOP mode for leaning, it really seems no different than leaning ROP except the bars go the other way.

Lycoming's position summed up is:

Operating an engine “on the edge” is possible provided the pilot

is extremely precise, has good instrumentation, and monitors the

engine condition full time. For 98% of the pilots, it is an invitation

to potential trouble. It only takes one brief episode of

mismanagement to incur deep internal damage that will cost

money later.

A) How is LOP on the edge? The edge of what? Peak? Peak is recommended. The too lean edge? How does that do harm?

Why does LOP have to be extremely precise? How does it require being precise any more than "50 ROP"?

C) How does ROP not require good instrumentation?

D) Why is it so critical to monitor the engine condition full time when LOP? I honestly don't understand the significance of this one. Set the mixture in cruise. As long as power, altitude, or air temp don't change, the mixture doesn't need to be touched either. During longer flights I would decide to relean the engine after time to find peak and set again and just return to the same place confirming it was right all along. LOP ends up being cooler so I'd almost think ROP requires closer monitoring of temps than LOP. What am I missing here? Why does it require "full time" monitoring?

E) What kind of trouble does LOP invite that Peak or ROP does not?

F) What is a "brief episode of mismanagement?" Going too lean would just make the engine start to sputter but no harm. Going too rich would bring you closer to peak and raise temps but no more than peak or ROP. So it really doesn't make sense to me how LOP can be more difficult or more damaging than ROP?

G) What kind of deep internal damage and how does LOP lead to it?

Every time I start to feel like I am understanding the theory and process of operating LOP, I am reminded by skeptics of how difficult/dangerous LOP is but I really can't understand how or why. Can anyone justify Lycoming positions for each of my points? Can anyone explain to what special care is needed for LOP that I may have been missing?

[Cruiser]

Mike, your questions would be good ones to ask Lycoming. It is very convenient for them to make those statements in a general sense without clarifying what they mean. I can't tell you what they were thinking.

Lycoming recommends best power at 100 - 150 ROP and best economy at peak so they don't care about a "red box". They recommend max CHT at 450°F or 475°F (can't remember without looking it up) anything else you what their guidance on?

An engine monitor will tell you what is happen with all cylinders all the time, ROP or LOP. If you watch it in your scan and don't do anything that makes CHTs climb abnormally high, you will probably be caring for your engine better than following all the guidance offered by Lycoming.