LOP operations

[Dave Siciliano]

Thought you might enjoy reading a post from George Braly at GAMI. 'Bout three years ago, I attended their first Advanced Pilot's Seminar. They demonstrated how to properly operate you plane's engine by showing empirical data gained on an engine test stand. You could watch the engine run and see the results graphically displayed. For those with graphic engine monitors and GAMIs (which my plane had) lean of peak operations were demonstrated. This was controversial. Now, look at where things are!!

Dave
=====================================================
David,

Had a rather amazing experience last Saturday morning.

Walter and I had gone out to Scottsdale to conduct a little 3 hour seminar for the Certified Lancair folks.

This is a rapidly growing group of Columbia 300, 350, & 400 owners.

There 40 of them in the room.

Also, Loren Lemon, TCM customer service manager was there.



At the beginning of our session, I decided to take a deep breath and see what we were up against.

So I took a poll:

"How many of you folks that own these brand new certified Lancair aircraft are routinely operating them lean of peak in cruise ?"

"Raise your hands, please ?"

Want to guess how many hands went up ?

I was stunned. :zap!:

Thirty-eight hands went up.

I asked the other two owners why they did not.

Their response was, "We were told by the Lancair check pilots to go take your class before we started operating LOP."

Can you imagine this type of result as little as three years ago???

Regards, George

 

[John J]

Dave

Thanks for the information . I find it very interesting. About 4 years ago I began running LOP and it is great. With the proper engine analysers and GAMI's I have saved quite a bit on fuel and the engine is healthy.


Thanks again

John J

 

[pete177]

I was re-reading the manual for my '64 m20e yesterday and was suprised to notice that the manual recommended running 25 degrees lop for economy operation using just the one egt and no analyzer. That said, lycoming doesnt recommend it for most pilots without gami's and a good engine analyzer and even then expresses doubt as to whether the average pilot will do it correctly every time and not end up way over lean . I also dont hear engine builders/overhaulers recommending it either. Most of the overhaulers/fbo owners/old aircraft owners that I've spoken to are not convinced it's a good idea. The only people I hear pushing it are trying to sell you something....thats a problem for me.

Pete

 

[gismo]

I was re-reading the manual for my '64 m20e yesterday and was suprised to notice that the manual recommended running 25 degrees lop for economy operation using just the one egt and no analyzer. That said, lycoming doesnt recommend it for most pilots without gami's and a good engine analyzer and even then expresses doubt as to whether the average pilot will do it correctly every time and not end up way over lean.

"Overlean" can't hurt anything except cruise airspeed once all cylinders are LOP.

 

[Dave Siciliano]

I also dont hear engine builders/overhaulers recommending it either. Most of the overhaulers/fbo owners/old aircraft owners that I've spoken to are not convinced it's a good idea. The only people I hear pushing it are trying to sell you something....thats a problem for me.

Pete[/QUOTE]

Well Pete, I think you'll find many engine rebuilders do recommend it if you dig a little further; Powermasters; Ultimate Engines and several others. Have you read about the new fuel management systems TCM is installing (FADAC)? Guess what, it uses LOP for long range, low power operations. Lycoming has recommended LOP on several engines at certain power settings.



If you speak to the old radial engine guys, guess what--they had a manner in which to compute best range power setting for patrol aircraft--it was LOP.



In WWII, Charles Lindbergh went over and taught the guys operating P-38s how to get more range--remember when they flew out and shot down the Japanese Naval Commander that orchestrated the Pearl Harbor attack. What he taught them was how to operate LOP.



Many of the folks out there have a malady I refer to as Psycho Sclerosis which may be loosely interpreted as "hardening of the ideas". Lots of empirical data on LOP. For each different thing you do, there is a trade off. Just understand what it is when you employ it.



Best,



Dave

A-36TN ADS

(who can make either coast non-stop when operating LOP)

 

[John J]

Dave;

I enjoy your note; My dad worked designing aircraft engines in the 1930s and 40's (P&W and Ranger). I so well remember him saying to me to "use the mixture control" I also spent many hours with a flight Engineer who worked the Wright R3350's,P&W R2800 and the P&W R4360 and he taught me so much about flying LOP. Yes Linbergh had that extra skill that helped so many pilots. Interesting I read his experiments when I was a kid and I became a believer a long time ago.


Thank again

John J

 

[pete177]

I'd hardly call this a recommendation, but hey, its your motor, you can call it whatever you like When you go lean of peak all you do is reduce cylinder chamber pressures. We've already got a lever for that....it's called a throttle Better yet, just fly high if the winds are workin' fer ya. Once your below 65% max chamber pressure I dont think there's much you can do to hurt the motor anyway as far as detonation caused by questionable fuel air mixtures. I'm currently replacing a motor prematurely that was operated lop. I cant tell ya that lop did it, but there are at least two burned pistons, so from now on I operate strictly according to the engine manufacturers instructions and recommendations.

www.lycoming.textron.com/ support/engineOperationTips/SSP700A.pdf

p.s. No engines were harmed in the making of this post. Well...maybe just one
Pete


[/QUOTE]
Well Pete, I think you'll find many engine rebuilders do recommend it if you dig a little further; Powermasters; Ultimate Engines and several others. Have you read about the new fuel management systems TCM is installing (FADAC)? Guess what, it uses LOP for long range, low power operations. Lycoming has recommended LOP on several engines at certain power settings.

Best,

Dave

A-36TN ADS

(who can make either coast non-stop when operating LOP)

[/QUOTE]

 

[Lance F]

I'm a believer in the data and have been running my IO360 LOP since I put in the JPI800. I'm very happy with the low CHTs and the fuel economy.
A couple of weeks ago I test flew a new Mooney Ovation 2 in the Mooney Freedom Tour. Their pilot said they wanted to fly ROP because the engine was new. I'm sure the 50 degree ROP they wanted to operate at was in the "red zone" that gives the highest internal pressures and highest CHTs. As I was greatful for the test flight (love that Garmin 1000!) and it wasn't my plane, I didn't say anything.
Note: the G1000 has a neat peak EGT find feature.

 

[Tom-D]

I'm a believer in the data and have been running my IO360 LOP since I put in the JPI800. I'm very happy with the low CHTs and the fuel economy.
A couple of weeks ago I test flew a new Mooney Ovation 2 in the Mooney Freedom Tour. Their pilot said they wanted to fly ROP because the engine was new. I'm sure the 50 degree ROP they wanted to operate at was in the "red zone" that gives the highest internal pressures and highest CHTs. As I was greatful for the test flight (love that Garmin 1000!) and it wasn't my plane, I didn't say anything.
Note: the G1000 has a neat peak EGT find feature.

This is the method of break in reccommended by many of the cylinder manufacturers. 50 Hours? seems a bit long.

 

[pete177]

I think in the end, at the power settings most of us cruise at we're really just splitting hairs. You fly slower (reduced chamber pressures) by going lop. I fly slower (reduced chamber pressures) by pulling the throttle back or flying higher, preferably higher. I've done several gps derived 4 way speed tests with my e model and I get the exact same ground speed at 10,800 ft (21" map/2400rpm/65%) as I do at 8000 ft (23" map/2400rpm/72%) running best power mixtures. As far as your cht's are concerned, reduced chamber pressures simply produce lower temps. The only difference is that a failure to monitor your engine properly during lop operations is more likely to result in damage. Your betting your engine that you'll never get distracted or make a mistake and your jpi will always funtion properly. Thats not my conclusion, thats lycomings.
Standard business school spiel...create a culture/demand and then develop products to fill that demand....gami.
Pete

I'm a believer in the data and have been running my IO360 LOP since I put in the JPI800. I'm very happy with the low CHTs and the fuel economy.
A couple of weeks ago I test flew a new Mooney Ovation 2 in the Mooney Freedom Tour. Their pilot said they wanted to fly ROP because the engine was new. I'm sure the 50 degree ROP they wanted to operate at was in the "red zone" that gives the highest internal pressures and highest CHTs. As I was greatful for the test flight (love that Garmin 1000!) and it wasn't my plane, I didn't say anything.
Note: the G1000 has a neat peak EGT find feature.

 

[Tom-D]

I think in the end, at the power settings most of us cruise at we're really just splitting hairs. You fly slower (reduced chamber pressures) by going lop.


I do not agree with your therory, You will make the same horse power LOP as you will ROP. on less fuel.

(reduced chamber pressures)

The proper term for that is BMEP (Break Mean effective pressure)

When we remember what we were taught as students in a fixed pitch prop aircraft with no EGT, CHT gauges. we were taught that you pull the mixture out until you feel a slight vibration.

Q.What causes that Vibration?
A. A lean misfire on the leanest cylinder.

Then we were taught that we should push the mixture in until the engine smooths out, and leave it there until the next throttle/power change, then do it again.

Were we running lean of peak?
Or
Rich of Peak?

My guess is, when we did it that way, we were running lean of peak for many many years and didn't even realize it.

 

[pete177]

"I do not agree with your therory, You will make the same horse power LOP as you will ROP. on less fuel."

No sir, that is incorrect. You will make the most horsepower aprox 100 degrees rich of peak. Best power mixture.

"(reduced chamber pressures)
The proper term for that is BMEP (Break Mean effective pressure)"

Ok

"When we remember what we were taught as students in a fixed pitch prop aircraft with no EGT, CHT gauges. we were taught that you pull the mixture out until you feel a slight vibration.

Q.What causes that Vibration?
A. A lean misfire on the leanest cylinder.

Then we were taught that we should push the mixture in until the engine smooths out, and leave it there until the next throttle/power change, then do it again.

Were we running lean of peak?
Or
Rich of Peak?

My guess is, when we did it that way, we were running lean of peak for many many years and didn't even realize it.

There can be quite a large temp spread between cylinders, especially on carburated, training/rental fleet aircraft. My guess is on a carburated aircraft you'd be somewhere around peak if you went just to the point you were running smooth after leaning yourself into a rough motor. I think most people are taught to use the rpm guage for finer adjustments, ie. lean to peak rpm (fixed pitch training airplanes) at a given throttle setting as opposed to just search for smooth. Sometimes cfi's will say "lean till the engine smooths out" while climbing, which is probably the way to go given the high power settings for climb, too rich as opposed to too lean. I was always taught peak rpm or lean until smooth, not lean until rough then back off till smooth. Thats a recipie for trouble if your fleet is being flown by students, I would think. My Mooney will run smooth way, way lean of peak, almost to the point of coughing right before the quiet begins It would be a very bad idea to use your method in that plane It's an io360a1a. Not that that motors is very smooth, it actually vibrates quite a bit, sort of like a harley with wings, so rough is a relative condition Anyway, thats my story and I'm stickin' to it
Pete

 

[Dave Siciliano]

Interesting discussion guys.



Well Pete, on an N/A plane you would be able to operate at lower power settings a lot lower than me (as a matter of fact, you wouldn’t have a choice when flying higher. I have sea level MP up to FL180 and had 25" of MP at FL 250 last Thanksgiving.



Best power setting for your engine (or maximum power) is different than getting the most power per gallon of gas burned which is called Brake Specific Fuel Consumption. On my TCM engine, about 75% ROP is where maximum power is created and also maximum internal cylinder pressures. As long as I'm running 60% power or less, probably doesn't hurt to run there. As I run higher power settings, ICP can get high.



Now let's think this trough. In my plane, I did a test to see where I obtained the same exact airspeed ROP and LOP (AP was holding altitude and heading). About 22 gallons per hour produced the same airspeed at 15 GPH on the lean side moving only the mixture control at the same MP in each case. That's because LOP is where fuel burns in a manner that produces the best power output per gallon burned. I have a retired Navy pilot in a hanger next to me that operated in the same manner at the end of WWI, after takeoff and climb, they would go to a max range power setting which was LOP.



Now, let's think of what we're doing to the engine (and btw, I have a graphic engine equalizer and GAMIs). There is an optimum mixture to air combination which is called stoichiometric combustion. If we burn richer that at that point, it's referred to as ROP; Lean of that means LOP. We have fuel, air and spark in a cylinder. If we have more fuel that at the optimum fuel/air mixture point, guess what's left over after combustion---fuel. The lead in that fuel left over is what we see accumulate on out valves from rich operations. If we have more air than fuel, which is what occurs LOP, guess what's left--air. At my last engine check, my valves were very clean.



Everyone can't run LOP and have the engine operate smoothly, but mine will slowly lose power until it dies out. If I slowly add mixture, if picks right back up. In a turbo engine like mine, one can easily operate it incorrectly ROP or LOP. I consistently run 75 to 80% power for six or seven continuous hours. If one runs it incorrectly for this period of time, it sure could damage things quickly. You may not find LOP operations useful, but it dramatically extends my effective range--by 20 to 25%. TCM has it built into FADAC; Lycoming has it recommended in the Malibu POH.



Do what you want to your engine. It's been working in mine for about four years and over 700 hours. And I'm going to continue to use it (as are several other Advanced Pilot Seminar graduates; and many others that are pretty savvy technically.). Doesn't fit everyone, but it sure it great for my plane and mission.



Best,



Dave

A-36TN ADS

 

[Tom-D]

[

My Mooney will run smooth way, way lean of peak, almost to the point of coughing right before the quiet begins It would be a very bad idea to use your method in that plane It's an io360a1a. Not that that motors is very smooth, it actually vibrates quite a bit, sort of like a harley with wings, so rough is a relative condition Anyway, that's my story and I'm stickin' to it[/color]
Pete[/QUOTE]

Let us NOT compare apples to oranges. Injected engines running a constant speed prop are different than carbs and fixed pitch.

A carb'ed engine can be leaned until lean misfire occurs on the leanest cylinder, and no damage will occur, you just don't have enough fuel to do any damage from heat or pressure, it simply is too lean to fire. (it skips due to the lack of fuel)

An injected engine/ constant speed prop, will run smooth until it quits for an all together different reason.

When you start to lean, as the engine receives the best fuel air ratio, it will make the best power, the prop compensates by taking a larger bite of air (larger blade angle) to remain on speed. so it goes faster and feels smoother.

(known to some as "on the step")

As you continue to lean the engine will make less horse power due to less fuel/heat, as this occures the prop will unload by taking a lessor bite, (lower blade angle) to remain on speed it still feels smooth but goes slower.

This is why you should never run lean of peak with out GAMI calibrated injectors, and an EGT system. You just don't know where you are by feel, or speed.

Best/highest BMEP will occur at peak temp, the reason for this is as simple as knowing what an engine is, "An engine is a mechanical device that converts heat to mechanical energy" So, best heat, best energy.

But running peak temps will harm your engine. It is a simple case of turning the wick up the lamp will burn brighter, but burn for a shorter time.

This is where we get the saying "turn the wick up turn the time down" Dr. Bruce's example of the TSIO-360-Cont not making it to TBO This is also why we like 65 % power rather than 75%.

Removing fuel to lower temps is as effective as adding fuel to lower temps, But we gain better engine life because we scavenge lead better when we run lean, in fact we burn less lead so we are better off from the start.

Why many people feel that running LOP is bad, They heard that someone, some where lost an engine while running LOP.

But I'll wager that if you could show me that engine I could show you one or more discrepancies that lead to the failure.

Such as advanced timing causing the peak BMEP to occur before TDC.
Bad Tach, causing the pilot to run over square beyond book limits.
Bad Plot practices running over square beyond book limits.
Bad EGT causing the Pilot to run at peak temp.
Running a cruise prop that is too high.

You simply can't do your engine damage until you run the BMEP off the upper end of the scale, you can't do this with mixture. You can lessen the BMEP to the point of NO BMEP by lean mixture. In fact that is how we secure the engine.

You can run the BMEP off the scale with RPM. (LOW RPM)

Most engines that are harmed by high BMEP are harmed by running too low of an RPM, this causes the piston speed to be too slow to travel down the cylinder fast enough to lower the expanding gas pressure. When this occurs the CHT will go off the scale, and the engine goes to melt down, because the high temp gases remain in the cylinder too long.

Typically we will see a piston failure or a cylinder hold down stud pulled out or maybe even a cracked case.

 

[pete177]

Interesting discussion guys.

Best power setting for your engine (or maximum power) is different than getting the most power per gallon of gas burned which is called Brake Specific Fuel Consumption. On my TCM engine, about 75% ROP is where maximum power is created and also maximum internal cylinder pressures. As long as I'm running 60% power or less, probably doesn't hurt to run there. As I run higher power settings, ICP can get high.

BSFC was not the question, that occurs at peak egt. Statement made was regarding best power...aprox 100 degrees rop, books typically say 75-100.


Now let's think this trough. In my plane, I did a test to see where I obtained the same exact airspeed ROP and LOP (AP was holding altitude and heading). About 22 gallons per hour produced the same airspeed at 15 GPH on the lean side moving only the mixture control at the same MP in each case. That's because LOP is where fuel burns in a manner that produces the best power output per gallon burned. I have a retired Navy pilot in a hanger next to me that operated in the same manner at the end of WWI, after takeoff and climb, they would go to a max range power setting which was LOP.

Ok, so your saying that you will make best power (go just as fast) at some setting lop as you will at best power mixture, 75 degrees rop. Not possible, your test was flawed. As you lean past max chamber pressure you produce less power, its that simple, if someone taught you otherwise you were lied to. See attached graph. And thats the whole crux of the discussion. Your going lop to reduce chamber pressures and you've got gami's and engine analyzers and paid for training to do it when all you had to do was run how your poh told you and reduce throttle and then you'd have a greater margin of error when it came to damaging your motor. These aren't my conclusions, their lycomings. How far lop were you when you supposedly re-obtained your max airspeed?
We're really not going to compare a WWI engine to what your driving, are we?



Now, let's think of what we're doing to the engine (and btw, I have a graphic engine equalizer and GAMIs). There is an optimum mixture to air combination which is called stoichiometric combustion. If we burn richer that at that point, it's referred to as ROP; Lean of that means LOP. We have fuel, air and spark in a cylinder. If we have more fuel that at the optimum fuel/air mixture point, guess what's left over after combustion---fuel. The lead in that fuel left over is what we see accumulate on out valves from rich operations. If we have more air than fuel, which is what occurs LOP, guess what's left--air. At my last engine check, my valves were very clean.

I agree completely, peak egt and beyond is cleaner, no question. Question is how much airspeed and margin of engine safety do you want to wager. If you want clean, peak egt is all you need, thats where your getting your best burn. If you want lower chamber pressures, yank on the aformentioned knob in the cockpit


Everyone can't run LOP and have the engine operate smoothly, but mine will slowly lose power until it dies out. If I slowly add mixture, if picks right back up. In a turbo engine like mine, one can easily operate it incorrectly ROP or LOP. I consistently run 75 to 80% power for six or seven continuous hours. If one runs it incorrectly for this period of time, it sure could damage things quickly. You may not find LOP operations useful, but it dramatically extends my effective range--by 20 to 25%. TCM has it built into FADAC; Lycoming has it recommended in the Malibu POH.

Hey, I've run my motor lop, like my book says, 25 degrees lop is recommended for max economy. Lycoming doesnt say it's bad if done correctly, they ask, is it worth the risk that one day you wont do it correctly, especially on your turbo charged motor. At your power settings when things start to go wrong, they're gonna go wrong fast. I'd bet that at 80% power you could find engine setting variables that could cause detonation. Hot day, bad load of gas, unplanned for rapid desent. Your not giving yourself any margin for error. Thats lycomings conclusion, I didnt design and test these engines, they did. Did you read the link I posted? Dont think it worked, go to lycoming-textron.com and do a search "lean of peak experts" and the first entry is it. I've attached the graph.
The gami guys also state they dont believe in shock cooling. They state to leave the mixture alone in desent, if I recall correctly. When your running at 50 to 75 degrees lop, temps drop off very quickly as you go leaner, like in a desent. Can you always take the time to manipulate the mixture correctly to keep temps even? No traffic, no atc requirements, no need to desend rapidly to get out of icing or other event? Hmm, I dont trust myself to do it right every time regardless of circumstances. I like a margin of safety. These motors were tested under specific operating parameters. Lycoming says your risking your motor if you operate out of them, not that your definately gonna break it, just that its unwise to experiment with your motor, especially when no one is prepared to fix your motor should you break it. If it was a better way to operate, dont you think lycoming would tell you that. Fewer warranty claims for them, enhanced reliabilty reputation for them. It would be difficult to convince me that the gami guys didnt just sell you snow in alaska. You already had all of the tools you needed to operate your motor safely and effectively.
Pete

 

[gismo]

Tom wrote:
"I do not agree with your therory, You will make the same horse power LOP as you will ROP. on less fuel."

No sir, that is incorrect. You will make the most horsepower aprox 100 degrees rich of peak. Best power mixture.

True if you maintain the same MAP and RPM. LOP concepts include the option of restoring power lost to leaning by raising RPM or MAP. If you are able to get the same IAS after leaning than you are running the same power output. That said, when you do this the fuel savings are typically a lot less than LOP advocates might lead you to believe. Also the efficiency claims by GAMI compare 100 ROP vs 30-50 LOP. For a turbocharged engine this probably matches reality pretty well, but IMO there's nothing damaging about running a NA engine 25-50 ROP at or below 65% power as long as the CHT's stay below 380 F. I seem to get about a half gph (per engine) between 30 ROP and 20 LOP (12.5 vs 13) if I increase the RPM or MAP to maintain the same IAS.

 

[pete177]

True if you maintain the same MAP and RPM. LOP concepts include the option of restoring power lost to leaning by raising RPM or MAP.
I agree, and would add raising map lop increases your chances of detonation in a turbo charged motor.

If you are able to get the same IAS after leaning than you are running the same power output. That said, when you do this the fuel savings are typically a lot less than LOP advocates might lead you to believe.

It is not possible to get the same ias lean of best power mixture as it is at best power unless as you say, you increase map, which will lead to the same chamber pressures, only on less fuel. Not recommended.

Also the efficiency claims by GAMI compare 100 ROP vs 30-50 LOP.

Not sure what "efficiency" means here. Producing best power or most complete burn? ( I know the terms, but I'm keeping it simple so everyone understands it)

For a turbocharged engine this probably matches reality pretty well, but IMO there's nothing damaging about running a NA engine 25-50 ROP at or below 65% power as long as the CHT's stay below 380 F. I seem to get about a half gph (per engine) between 30 ROP and 20 LOP (12.5 vs 13) if I increase the RPM or MAP to maintain the same IAS

Exactly. At 65% or below, chamber pressures are so low as to negate most anything stupid that we do. The only question is how we reach 65% power. The poh's provide power charts based on best power mixture. One of the things that confuses people in this debate is that they think that if they're running say, 30"map and 2400 rpm that they're running at 80% power regardless of mixture, and that it is ofcourse completely false. They're really running at 65% because they've reduced the available chamber pressures by making the mixture inefficient.
Hey, gami's are regarded as very good injectors, and if it was time to replace mine, then I would by all means, buy'em. But, makes no sense to do it sooner just because there's a new snake oil salesman in town. Engine analyzers are great too...just bought one, but hey, it's time...gettin a brand new motor and my guages are 40 years old and behave that way
Pete

 

[pete177]

[

Let us NOT compare apples to oranges. Injected engines running a constant speed prop are different than carbs and fixed pitch.

Your reference was to "how you were taught" "lean until it gets rough and then rich until it smooths" I assumed you were taught in a training plane, 150 or 172, fixed pitch, carburated. I wasnt comparing apples to oranges at all.

A carb'ed engine can be leaned until lean misfire occurs on the leanest cylinder, and no damage will occur, you just don't have enough fuel to do any damage from heat or pressure, it simply is too lean to fire. (it skips due to the lack of fuel)
An injected engine/ constant speed prop, will run smooth until it quits for an all together different reason.
When you start to lean, as the engine receives the best fuel air ratio, it will make the best power, the prop compensates by taking a larger bite of air (larger blade angle) to remain on speed. so it goes faster and feels smoother.

Belaboring the obvious and repeating what was said already.

(known to some as "on the step")

That is a reference to a stage encountered during a sea plane taxi or takeoff. The floats "come up on step". Never heard nor read of it used to describe reaching best power mixture.

As you continue to lean the engine will make less horse power due to less fuel/heat, as this occures the prop will unload by taking a lessor bite, (lower blade angle) to remain on speed it still feels smooth but goes slower.

Obvious

This is why you should never run lean of peak with out GAMI calibrated injectors, and an EGT system. You just don't know where you are by feel, or speed.

Not gettin' it...What is why? You know where you are because the engine will get rough and or you'll lose airspeed. My poh recommends to go as far as 25 degrees lop using 1 egt. You dont need gami's or an egt system at all, just do what the poh told you and keep your chamber pressures low by cruising at 65%. No mystery there. Your doing the same thing by using an inefficient mixture, only you paid alot more to someone who sold you a bunch of stuff you dont need and are operating your motor with less margin for error, again, thats lycomings conclusion. The question becomes, who do you want to believe, the guys that built the motor and have decades of testing and use or some johnnie come lately's who are trying to sell you stuff the factory says you dont need and may even damage engine when you operate outside of recommended paremeters.

Best/highest BMEP will occur at peak temp,

Ok, there is best power which occurs at 75 to 100 rop, and then there is highest bmep which occurs at some point between best power and peak tit/egt. There is no best/highest anything.

the reason for this is as simple as knowing what an engine is, "An engine is a mechanical device that converts heat to mechanical energy" So, best heat, best energy.
But running peak temps will harm your engine. It is a simple case of turning the wick up the lamp will burn brighter, but burn for a shorter time.
This is where we get the saying "turn the wick up turn the time down" Dr. Bruce's example of the TSIO-360-Cont not making it to TBO This is also why we like 65 % power rather than 75%.

belaboring the obvious again.

Removing fuel to lower temps is as effective as adding fuel to lower temps, But we gain better engine life because we scavenge lead better when we run lean, in fact we burn less lead so we are better off from the start.

You are burning most efficiently (ie, all your fuel) at peak tit/egt. Beyond that you become inefficient and simply trade away power at an ever increasing rate while operating your motor outside the manufacturers recommendations. There is absolutely no reason to go out and buy gami's and engine analyzers so you can do this without blowin' your motor up. If you operate the way the manufacturer suggests you will have a greater margin of safety and stay within tested parameters.

Why many people feel that running LOP is bad, They heard that someone, some where lost an engine while running LOP.
But I'll wager that if you could show me that engine I could show you one or more discrepancies that lead to the failure.
Such as advanced timing causing the peak BMEP to occur before TDC.
Bad Tach, causing the pilot to run over square beyond book limits.
Bad Plot practices running over square beyond book limits.
Bad EGT causing the Pilot to run at peak temp.
Running a cruise prop that is too high.

Yup, thats their spiel.

You simply can't do your engine damage until you run the BMEP off the upper end of the scale, you can't do this with mixture.

Really? Try leaning while your climbing on a hot day and watch what happens.

You can lessen the BMEP to the point of NO BMEP by lean mixture. In fact that is how we secure the engine.

Right, at idle throttle.

You can run the BMEP off the scale with RPM. (LOW RPM)

Yup...good point.

Most engines that are harmed by high BMEP are harmed by running too low of an RPM, this causes the piston speed to be too slow to travel down the cylinder fast enough to lower the expanding gas pressure. When this occurs the CHT will go off the scale, and the engine goes to melt down, because the high temp gases remain in the cylinder too long.
Typically we will see a piston failure or a cylinder hold down stud pulled out or maybe even a cracked case

good advice.

Pete

 

[Richard]

This is a great discussion. When I attended APS last Jan. I was quite skeptical but listened politely. Before the end of the class I was completely sold on WOTLOP (WideOpenThrottle). Of course, I had been aggressively leaning for years, I just wanted to hear their take on it. Boy, were my eyes opened.

 

[mauricefrompolo]

I have read this entire thread and must say that I am more confused than enlightened. I was under the impression that LOP developed more heat in the cylinders. And fuel was used as a coolant.

I have an "E" model Mooney with a brand new injected engine in it and I am worried about the leaning process of burning something up. Granted it does not have all the fancy gauges etc that the new aircraft have. It has just a single EGT, which brings up another topic. There are no markings on the EGT other than hash marks across the front. How am I to interpret this? I have no idea in the world what the actual temperatures I am running. Therefore, so far I have been leaning, watching the needle climb and holding it shy of being in the middle of the dial.

As you guys can see I need some help. I have been told by the engine manufacturer to run it at 65%-75% power for the first 50 hours while advancing it to full power for a period of 30 seconds every 15 or 20 minutes. Any help you can give me is greatly appreciated.

 

[Ted]

Mooney E, sounds like you need some specialized instruction. APS offers their courses, I offer instruction in the plane. Make sure that you get your instruction from someone who actually understands engines - many do not.

For engine break-in, following Lycoming Service Instruction 1427B to the letter is the way to go. After the engine is broken in fully (under 50 hours), then you can lean via other methods.

 

[SCCutler]

I love the historical chronicle that this thread represents, sort of a Pilots of America illustration of community excellence. Can it really have been seven years?

Dave has moved on from the Bonanza to the P-Baron, and now, to a King Air 90. His P-Baron's engines are being overhauled, after (IIRC) over 2,200 hours of LOP operation, and still running strong.

 

[Lance F]

I have read this entire thread and must say that I am more confused than enlightened. I was under the impression that LOP developed more heat in the cylinders. And fuel was used as a coolant.

I have an "E" model Mooney with a brand new injected engine in it and I am worried about the leaning process of burning something up. Granted it does not have all the fancy gauges etc that the new aircraft have. It has just a single EGT, which brings up another topic. There are no markings on the EGT other than hash marks across the front. How am I to interpret this? I have no idea in the world what the actual temperatures I am running. Therefore, so far I have been leaning, watching the needle climb and holding it shy of being in the middle of the dial.

As you guys can see I need some help. I have been told by the engine manufacturer to run it at 65%-75% power for the first 50 hours while advancing it to full power for a period of 30 seconds every 15 or 20 minutes. Any help you can give me is greatly appreciated.

I commend you for trying to learn about te best way to run your new Mooney.. First the break in you describe in the last paragraph just ain't right. Run it wide open throttle, full rich at low altitude for extended periods. Do two long (2 to 3 hour) cross countries, and you'll be done. Yep, 5 hours will do it. Change the oil and you're good to go.

The absolute EGT temperature is of no useful value, hence the lack of numbers on your gauge. After the break in pull the red knob back and watch the needle go up. That's rich of peak (for the cylinder that has the probe). At some point of leaning the needle won't go any higher. That's peak. Lean further and the needle will start going down. That's lean of peak. Simple.

Lycoming IO360s run great LOP.. Enjoy your plane.

 

[Dave Siciliano]

We talked to Bill Cunningham at Powermaster about how to run our new engines when the P Baron is ready. No break in period, no special oil. Bill said after the test runs and runups the rings will be seated and he like us using single grade oil (We use AeroShell 100 and have for about 12 years on the A-36 and the P-Baron. Some folks still do that breakin period with a different lubricant for a short period of time, so, I'm certainly not recommending all do what we do, but in our case with new Milliniums cylinders that have been balanced and blue printed: no formal breakin.

My partner and I are heading up to Tulsa shortly to monitor progress on the 58.

Best,

Dave

 

[Henning]

We talked to Bill Cunningham at Powermaster about how to run our new engines when the P Baron is ready. No break in period, no special oil. Bill said after the test runs and runups the rings will be seated and he like us using single grade oil (We use AeroShell 100 and have for about 12 years on the A-36 and the P-Baron. Some folks still do that breakin period with a different lubricant for a short period of time, so, I'm certainly not recommending all do what we do, but in our case with new Milliniums cylinders that have been balanced and blue printed: no formal breakin.

My partner and I are heading up to Tulsa shortly to monitor progress on the 58.

Best,

Dave

Here's the deal on break in oil, if you have paper filters, use what you normally use. If you have only a screen, use a 'straight mineral' non AD oil for the first run.

 

[Dave Siciliano]

Yes Spike; great to look back. We continued to run the TN A-36 past TBO LOP. John Foose purchased it from me and ran it several more years that way before putting in an new engine because he wanted to fly behind that new engine before he got too old to continue flying.

I purchased the P Barron in June of '05 and we ran it over 2,200 hours LOP which is more than 600 past TBO. Couple cylinders finally gave out and we just wanted to firewall forward it at a boutique shop. We'd side funded all the money and just wanted the best engines we could reasonably get. Bill had our engines apart and said there was noting in the case that would have caused damage near term, but there was wear that eventually would have needed attention. One cam will have to be ground 10 thousands to meet specs, the other was fine. Cranks were fine, counterweight pins showed wear but no real issues. So, it probably was time, but we didn't need to rush (g).

Best advise I ever received was from George and his crew when I began flying that A-36. Had many friends that strongly disagreed and gave all the anecdotal reasons. Most got on the cylinder manufacturer's Holiday card list---I fell left out (sarc).

Best,

Dave

 

[Tom-D]

This was controversial. Now, look at where things are!!

snip

Can you imagine this type of result as little as three years ago???

Regards, George



[/size]

Simply amazing isn't it, after nearly 80 years of operating the radials LOP and all Lindberg's discoveries, the GA guys think it was only 3 years.

I guess all deacon's writings, and all the military operations manuals didn't mean squat.

 

[Tom-D]

We talked to Bill Cunningham at Powermaster about how to run our new engines when the P Baron is ready. No break in period, no special oil. Bill said after the test runs and runups the rings will be seated and he like us using single grade oil (We use AeroShell 100 and have for about 12 years on the A-36 and the P-Baron. Some folks still do that breakin period with a different lubricant for a short period of time, so, I'm certainly not recommending all do what we do, but in our case with new Milliniums cylinders that have been balanced and blue printed: no formal breakin.

My partner and I are heading up to Tulsa shortly to monitor progress on the 58.

Best,

Dave

And what have I been preaching til I'm blue in the face?

OH no, you gotta have mineral oil, and run it hard,,,,, BS.

 

[Tom-D]

Mooney E, sounds like you need some specialized instruction. APS offers their courses, I offer instruction in the plane. Make sure that you get your instruction from someone who actually understands engines - many do not.

For engine break-in, following Lycoming Service Instruction 1427B to the letter is the way to go. After the engine is broken in fully (under 50 hours), then you can lean via other methods.

We all know the LycomingSB is BS and has been proven so many times specially when there are Superior or ECI cylinder installed.

I have a new set of ECI 0-200 nickel cylinders at the hangar, I will take a few pictures of them and show you how smooth these bores are, they take no break in procedure, fly them normally from day 1 to TBO, on any good AD oil. multi or not.

 

[DouglasBader]

I've been running lean of peak for many years on everything from small A65's to large radials. I've never had an issue, and those who fight against lean of peak operations don't understand the principle of leaning. I've lost track of the number of people who think that running lean of peak causes higher temperatures. It goes downhill from there.

I was once confronted by an angry site manager in an operation involving a large number of similar piston aircraft. After each sortie we were to fill out an after action report, which included, among other things, the fuel burn from the mission. My burns averaged about 25% less than anyone else. I was told that I was making others look bad, or that my practices were questionable. The difference was power setting, and running lean of peak. I never had any trouble with any powerplant, and my temps ran lower. I didn't have issues with engines loading up.

Running lean of peak is a lot easier and a lot more precise if one has multipoint monitoring. If one is running at power settings of barometric or less, one can't hardly hurt the engine.

When manufacturers give conservative guidelines such as maintaining 100 degrees rich of peak, they're speaking to the lowest common denominator: they're attempting to idiot proof their equipment against pilots. Same thing for advising pilots not to lean below several thousand feet of altitude; they're trying to get the output power below 75-80% in an effort to idiotproof the process and cut liability. One can lean right off the bat, and should, if one knows what one's doing. Same for running lean of peak.

Mixture use is one of the most misunderstood and misapplied skills in operating aircraft piston engines, right next to the use of carburetor heat. Most instructors don't seem to have a firm grasp on the subject, let alone their students.

Lean of peak is quite safe and proper, if done properly

 

[Henning]

Simply amazing isn't it, after nearly 80 years of operating the radials LOP and all Lindberg's discoveries, the GA guys think it was only 3 years.

I guess all deacon's writings, and all the military operations manuals didn't mean squat.

I always found that funny as well. 20 years ago an 83 year old man taught me LOP operations that he had learned when he was 20 during WWII. There is nothing new here.

 

[Sac Arrow]

It might be interesting to note that a typical, modern (year 2000+) EFI automobile and truck gasoline engine runs lean of peak. And they are capable of running quite a long time. The problem with running LOP in a carburated automobile engine is one of power regulation - once you enter LOP you lose the ability to regulate power with the throttle. Modern EFI engines regulate both airflow and fuel flow in response to power demand so it really doesn't matter which happens to be in excess at the time.

If you've noticed while running LOP in an airplane, once you've entered the LOP regime, you regulate power with the mixture, as there is already an excess of air. Much like a diesel engine, which always has an excess of air.

When I first got my Turbo Arrow I was dismayed at its economy. Then I learned about running LOP. Not only did my economy improve to something more to my expectations, but my A&P reported better engine health, through borescopes and compression tests after I started running LOP.

 

[Ted]

We all know the LycomingSB is BS and has been proven so many times specially when there are Superior or ECI cylinder installed.

I have a new set of ECI 0-200 nickel cylinders at the hangar, I will take a few pictures of them and show you how smooth these bores are, they take no break in procedure, fly them normally from day 1 to TBO, on any good AD oil. multi or not.

I've done it enough times both ways. Yes, I only ran factory parts. I can't speak to ECI or Superior cylinder installs because I don't buy them and I didn't run them in the lab. You're on the opposite side - you hate Lycomings and their factory parts, so you probably don't have much experience doing that.

The SB is written the way it is for a reason and it works well. It's what I've used on the Aztec when I bought new cylinders. I certainly would concede that on Superior or ECI cylinders it may not be necessary, however the factory cylinders on a Lycoming are typically going to benefit. Keep in mind the factory Lycomings are nitrided and are harder than the Superior and ECI cylinders, which are not made out of the same metal using the same processes. How difficult it is to seat rings is mostly a function of hardness of the components. Use components that aren't as hard, and they'll seat easier.

600 hours since the top overhaul on my Aztec's left engine. Used the Lycoming SB. They broke it quite nicely (it was easy to see on the engine monitor as they broke in). Lowest compression is 78. The previous cylinders that were on that engine (Superiors) only had 600 hours since they were new. Highest compression on there was a 65 when I pulled them off.

 

[Ted]

Best advise I ever received was from George and his crew when I began flying that A-36. Had many friends that strongly disagreed and gave all the anecdotal reasons. Most got on the cylinder manufacturer's Holiday card list---I fell left out (sarc).

When I started flying the Aztec LOP, I got the same story from my mechanic. "Goodbye cylinders!" Well, the left engine cylinders that I replaced were close to failing compressions when I bought the plane, and I did a top overhaul. 900 hours on the plane total under my ownership, and I'm burning 8 gph less combined vs. other Aztecs to only go a hair slower. And I don't have cylinder problems. My A&P is starting to believe me.

The 310 is now at 2100 SMOH (400 past TBO), with me running it LOP since it hit TBO, and the previous owner having run ROP (but done correctly). It's about time for engines. Next ones will be run LOP their whole life, it will be fun to see the results. I'm guessing my A&P will be in a greater state of disbelief.

 

[Henning]

When I had the 310 at Aviation Classics for the panel they were telling me of all the doom and gloom I faced running LOP.

 

[bluesky74656]

Is it still the recommended advice that you shouldn't attempt to operate LOP with only one basic EGT gauge? You'd need to get some kind of fancy engine monitoring computer before you can try it safely?

 

[Henning]

Is it still the recommended advice that you shouldn't attempt to operate LOP with only one basic EGT gauge? You'd need to get some kind of fancy engine monitoring computer before you can try it safely?

Nope, I ran LOP safely with 2 single points for 10 years. It's safe to run with none at all even as long as you keep your power down, in your basic low compression 180hp and less engines, once you're above a couple thousand feet is next to impossible to get into detonation if the timing is correctly set, and that is the ONLY risk associated with LOP, has nothing to do with valves except saving them and preventing them from sticking. If you have a fixed pitch climb prop, I doubt you could manage detonation anywhere.

 

[Ted]

Is it still the recommended advice that you shouldn't attempt to operate LOP with only one basic EGT gauge? You'd need to get some kind of fancy engine monitoring computer before you can try it safely?

Depends on the engine and the installation. On my Aztec, I wouldn't recommend it because the engines have very poor cooling. You'll likely run the heads far too hot. On the OP's Mooney, I don't think it matters much, but I'd ask Lance Flynn what temps he runs in his, and that'd give you a better idea.

On the Navajo, yes, it definitely matters. Even at cruise powers, you can hurt it.

 

[Ted]

Nope, I ran LOP safely with 2 single points for 10 years. It's safe to run with none at all even as long as you keep your power down, in your basic low compression 180hp and less engines, once you're above a couple thousand feet is next to impossible to get into detonation if the timing is correctly set, and that is the ONLY risk associated with LOP, has nothing to do with valves except saving them and preventing them from sticking. If you have a fixed pitch climb prop, I doubt you could manage detonation anywhere.

The other risk is when people don't run lean enough LOP, and then have high CHTs and resultant cylinder issues. This is the reason why most A&Ps I come across think LOP is bad - because people who do it wrong toast cylinders.

 

[Henning]

The other risk is when people don't run lean enough LOP, and then have high CHTs and resultant cylinder issues. This is the reason why most A&Ps I come across think LOP is bad - because people who do it wrong toast cylinders.

True, but if you make your target power airspeed and then lean until speed loss, you'll be plenty lean. There are other ways to play the game. WWII how many planes had multipoint sensors? They all operated LOP, every one of them. Mechanics are a lot like flight instructors in that regard, they say things even when they don't know what they're talking about because they feel they should.