tried LOP for the first time - have some questions

[John Pleisse]

Quote: KSMooniac

[Becca]

Quote: Shadrach

I cruise WOT LOP at 3K often when on short trips (<1hr). If I followed my POH, I'd be burning 6-7GPH more on those missions. Lopresti was running his 201 this way in the early and mid 80's when he participated in the Cafe 400 races. 

[Becca]

Quote: N4352H

You should have appealed to his "green" side, citing the environmental benifits! Smaller carbon footprint, less fuel, cleaner exhaust, less engine wear.

Wow...I am feeling cozy...just thinking about it.

[Becca]

Quote: N4352H

John,

What you've said about LOP ops is a common misconception. However, LOP or "lean of stoichiometric" operations are pertinent to combustion propulsion science and engineering...period.  Just about every Modern/semi-modern injected internal combustion engine on the planet runs lean of stoic, depending on power demand. Lean air/fuel ratios and the technology that enables them has contributed largely to improved fuel economy in every machine that burns hydrocarbons.  The main reason auto technology is going towards direct injection is to enable autos to run extremely lean air/fuel ratios in excess of >50:1 which is far leaner than we could ever achieve with our constant flow port injection set ups.  It has nothing to do with Continental vs Lycoming. Ignited Avgas cares not about the name embossed on the rocker covers...

The genesis of Gami injectors was born out of Continental's intake design (log runner intake) and that systems inherent flaws with regard to fuel distribution (not air distribution, which is another common misconception). Gamis will benefit any Continental with a log runner intake system regardless of whether it is run LOP of ROP. While the owner of GAMI (George Brawly) is also involved with Advanced Pilot Seminars (APS) and also happens to currently operate a Continental, it does not mean that LOP operations are only "pertinent" to "big bore Continentals".

I think people should operate as they choose. However, I think it's better to be informed about how that choice affects the combustion event and its effects on CHT and EGT which in turn have an affect on both engine health and economy.

Lycoming has no incentive to revise it's POH (BTW, the power settings per the POH are recommendations, not limitations) and in fact has a legal incentive not to revise based on what they've been saying for the past 5 decades. They're tune changed at Oshkosh this year.

All of that being said, anyone with even a rudimentary knowledge of combustion science would have an impossible job reconciling lycoming's past stance that "peak EGT settings are safe, but LOP settings are dangerous".  It is an intellectually and scientifically unsupportable position.

I fault no one for following the POH, but those recommendations are not always the best course of action. For those that know what they are doing, deviating from the "cook book" can enable them to enhance performance and also be kinder to their engine, for those that don't, running per POH is certainly not going to hurt anything...most of the time. 

 

 

[jetdriven]

To show how far from reality Lycoming's advice is, here is their own data, which clearly shows detonation beginning at ~60 ROP, maximum intensity at ~10 ROP, and completely gone at ~40 LOP. 29" of MP and 2400 RPM.  Note the CHT is nearly 500 degrees.  

Do I run my engine this way?  Certainly, at 50 LOP or greater.  (not the CHT though)

Quote: N4352H

Your point about the detonation margins at 50 LOP is incorrect.

[jetdriven]

Had you operated it LOP all this time you would have a free engine overhaul in fuel saved.  Well, not quite at 2$ per gallon, but a mathematical certainty at 5$ a gallon. 

Quote: N4352H

Well, I guess you're just quoting Lycoming then when you posted this a couple of times:  While this could be dismissed as arrogant, they readily point to the narrow margins at 50 degrees LOP 

The detonation margins are much, much narrower at 50 ROP (where they recommend) than they are at 50 LOP.  I don't want the debate to get muddled with incorrect statements when folks are trying to learn what is true and what is not.

I'm not sure if you're advocating Lycoming's position or playing devil's advocate... whatever the case my intentions are not to offend or make you (or anyone) feel cornered.  I just want the facts presented.  

[jetdriven]

Quote: N4352H

 Byron...what was the Rep's name?

[jetdriven]

All the time you hear, well, I had a dirty injector and burned up a cylinder. ROP, a little leaner with a clogged injector, that cylinder operates at peak with a 500 CHT until it is dead.   Your single probe on #3 doesnt tell you what the others are doing.

Now that same engine operated LOP, the pilot would notice it will not run smooth LOP. That clogged injector cylinder is leaner and will not run smooth.  So run real rich, and before further flight, check it out.  That's 2K saved for a new angle valve cylinder right there.  Plus a grand in labor.  

LOP is likely safer.

Quote: Becca

So, maybe this retired guy from JPI sold me, but I think we should all separate the idea of getting an engine monitor from the LOP/ROP debate and just look at it on its own merits.  Engine monitors tell you so much about the health of your engine and your cylinders, I feel like it should be high on everyone's upgrade lists regardless of which side of the LOP/ROP debate you are on.

[scottfromiowa]

http://www.insightavionics.com/g3lean.htm

A pretty "idiot proof" instrument...The G1 is coming soon and will be under $800 for 4-cylinder aircraft...I'm in for G2 when it comes out.

[John Pleisse]

Quote: jetdriven

Your point about the detonation margins at 50 LOP is incorrect.

[carusoam]

N4352h,

I could not find a date on the linked paper you provided.  

The paper indicates that operating LOP is on the "edge" for 98% of GA pilots.

Lycoming won't give procedures for specific a/c installations.

The only drawback to LOP is detonation.  

There was no mention of oxygen rich corrosive environment.

We should only trust Lycoming because they warrantee the engine.

We should not trust "experts" because they do not warrantee the engine

My conclusion after reading all four pages...

We must be in the 2%, with proper instrumentation, and training.  We appreciate the savings a few dollars per hour, we don't mind going a few knots slower on some flights.  Our engines are out of warrantee already.

 

I was hoping the Lycoming paper was about how to safely operate LOP.  It was more about....it can be done, we know how, and you don't.  We are the experts and you are not.  It takes knowledge of you fuel system, but we're not telling you how.

Overall I feel better about my Continental and think George Braly and co. at GAMI is the real expert.

I do like the graph.  We need to add the one with the red box next to it.

 

Best regards,

-a-

[Shadrach]

Quote: N4352H

Asserting, in a public forum, 12 year old information as Lycoming's position today is intentionally misleading.

http://www.lycoming.textron.com/support/troubleshooting/resources/SSP700A.pdf

 

 

[Shadrach]

Quote: carusoam

The only drawback to LOP is detonation.  

Best regards,

-a-

[carusoam]

Ross,

What do "they" mean?...

I summarized what I read in the Lycoming paper.  I was hopeful to find additional concerns such as increased oxidation or something an expert would only know.

The only negative given by the paper is detonation.  Yes it is important, and we are all aware of that one.  Detonation is only an issue if are too busy and/or lean incorrectly.  (again, according to the paper).

It seems the Lycoming paper is more of an opinion piece than a science document.

I am hoping we are in the 2%. Educated, instrumented, and sharing in the details.

I agree with the Lycoming opinion in some places.  When the environment is too busy, I climb or descend ROP.  Keep the single EGT in the blue box method.  Flying IFR in the NY area can be hectic during the first few minutes of departure.

I hope that covered your "what do you mean" question...?

Best regards,

-a-

[John Pleisse]

Quote: carusoam

N4352h,

I could not find a date on the linked paper you provided.  

The paper indicates that operating LOP is on the "edge" for 98% of GA pilots.

Lycoming won't give procedures for specific a/c installations.

The only drawback to LOP is detonation.  

There was no mention of oxygen rich corrosive environment.

We should only trust Lycoming because they warrantee the engine.

We should not trust "experts" because they do not warrantee the engine

My conclusion after reading all four pages...

We must be in the 2%, with proper instrumentation, and training.  We appreciate the savings a few dollars per hour, we don't mind going a few knots slower on some flights.  Our engines are out of warrantee already.

 

I was hoping the Lycoming paper was about how to safely operate LOP.  It was more about....it can be done, we know how, and you don't.  We are the experts and you are not.  It takes knowledge of you fuel system, but we're not telling you how.

Overall I feel better about my Continental and think George Braly and co. at GAMI is the real expert.

I do like the graph.  We need to add the one with the red box next to it.

 

Best regards,

-a-

[carusoam]

 

N4352H,

The Lycoming document I summarized is on their website.  It is copyrighted 2000, noted on page two.  If it is not their current viewpoint, it should not be readily available by any truther.

Do they have a document on how to run a Mooney LOP?  I would be happy to read and summarize it.

Don't get me wrong, I like Lycoming as a company and provider of aircraft engines.  They have just been unable to help people run Lycoming engines LOP.  This happens to be a method that many users want to use and are looking for expert advice on how to optimize the experience and minimize any associated risk.

Keep in mind, I am not currently a Lycoming user.  I have a continental IO-550G.  Mooney publishes LOP opps in the POH for this engine.

Best regards,

-a-

 

[jetdriven]

It's not intentionally misleading, this is a Lycoming test cell data on an IO-360 engine done in 2002.  The precise engine that people are spouting off how the engine has narrower detonation margins LOP.  Which IS false.   Lycoming's own official "position" and the "facts" spouted off by their employee, Wayne G, are completely in conflict with each other. The man trying to sell me a 42K $ IO-390 package.

Has Lycoming's position changed?   What is it now? And again, what scientific data is it based on?   Or is it an old wives tale?

Quote: N4352H

I never compared the two Scott.... and on the rich side you can dump fuel and use fuel to cool at greater margins. This is Lycoming's position...not mine. The disconnect is the science vs. what the engine maufacturer suggests. Tell Lycoming they are wrong all day.....

[jetdriven]

Lycoming authorizes PEAK power at 75% and below.  Which is certainly in detonation territory at about 75% power.     This is recommended by Lycoming, although LOP is not.  Ours runs smooth at 28" of MP and 2500 RPM right down to about 100 LOP, at this point the CHT is 280, the FF is around 7 GPH.  Yep, really killing it.

Today we advanced the mag timing to 25 degrees, it was incorrectly set at 20.   The engine wil now get up to a 380 CHT pretty easily at 11 GPH, this is 75 ROP at 25 squared.  At 30 LOP the CHT is 365.   So, should I follow Lycoming's advice and trash a set of cylinders based on their recommendation? They also recommend 475 as a redline CHT, so, 470 all day is fine too?

Lycoming is stuck in the 1950s. 

Quote: KSMooniac

Actually I have run LOP power settings from 50% (actually a bit less) all the way up to 85% power.

Regarding Lycoming, just a few posts above jetdriven (Byron) posted an exchange he had with a Lycoming rep that wandered into his hangar and spouted off some very erroneous info regarding LOP ops.  

LOP ops result in lower peak internal cylinder pressures and cooler CHTs, which yields a much longer fatigue life (ie less chance of cracking).  This means that is is highly likely that 2000 hrs of LOP ops will leave a cylinder in great shape for an overhaul whereas ROP ops might lead to cracking due to the higher pressures and temperatures.  Angle valve jugs are sole-source Lycoming, and they cost twice as much as parallel valve jugs that have aftermarket competition.  This means a potential savings of $4k on a set of 4 if you choose to overhaul instead of replace.

One more fact... the detonation margins at 50 LOP are MUCH greater than they are at 50 ROP.  Detonation needs high temps and high pressures, and 50 ROP is far more prone to detonation than 50 LOP!

[carusoam]

JetD,

Question for the Lycoming guy...

Would we be able to run an IO-390 LOP in a mooney application?

I won't hold my breath waiting for a reply.  The last time Lycoming pushed new technology with a mooney, the TLS turned into the Bravo.

That must have been a memorable expensive experience.

Best regards,

-a-

[John Pleisse]

Quote: carusoam

 

N4352H,

The Lycoming document I summarized is on their website.  It is copyrighted 2000, noted on page two.  If it is not their current viewpoint, it should not be readily available by any truther.

Do they have a document on how to run a Mooney LOP?  I would be happy to read and summarize it.

 

[John Pleisse]

Quote: jetdriven

Has Lycoming's position changed?   What is it now? And again, what scientific data is it based on?   Or is it an old wives tale?

 

Well one thing is for certain, grabbing the first hit you see on google, doesn't answer that Byron.

[Cruiser]

as for detonation margin, where is the data that shows what operating margin exists across the mixture range? I hear statements of less, more, danger, safe etc. What data are these statements based on?

Can someone point me to a reference I can check? Specifically for our IO360 Lycoming engine?

[jetdriven]

What does?

Quote: N4352H

[Shadrach]

Quote: carusoam

Ross,

What do "they" mean?...

I summarized what I read in the Lycoming paper.  I was hopeful to find additional concerns such as increased oxidation or something an expert would only know.

The only negative given by the paper is detonation.  Yes it is important, and we are all aware of that one.  Detonation is only an issue if are too busy and/or lean incorrectly.  (again, according to the paper).

It seems the Lycoming paper is more of an opinion piece than a science document.

I am hoping we are in the 2%. Educated, instrumented, and sharing in the details.

I agree with the Lycoming opinion in some places.  When the environment is too busy, I climb or descend ROP.  Keep the single EGT in the blue box method.  Flying IFR in the NY area can be hectic during the first few minutes of departure.

I hope that covered your "what do you mean" question...?

Best regards,

-a-

[Shadrach]

Quote: Cruiser

as for detonation margin, where is the data that shows what operating margin exists across the mixture range? I hear statements of less, more, danger, safe etc. What data are these statements based on?

Can someone point me to a reference I can check? Specifically for our IO360 Lycoming engine?