Lean Of Peak -O-Meter

[Dynon101]

Can someone please explain the ROP/LOP indications?

It seems at the top of the EGT the system displays the cylinder number of the cylinder that peaked first...makes sense

What is confusing is that the cylinder number of LOP cylinder is displayed is above the wrong cylinder number of the EGT display.

I presume all it is doing is displaying the first cylinder on the left and then as each additional cylinder gets to peak it appears to the right of the first one?!?!?

If this is the case...it would make more sense if the cylinder LOP status would appear on top of its respective cylinder...

 

[Dynon]

The number when you're in peak mode reflects the order in which it reached peak, not the cylinder number. The cylinder number is locked to the particular graphical slot.

 

[Dynon101]

> The number when you're in peak mode reflects the order in which it reached peak, not the cylinder number. The cylinder number is locked to the particular graphical slot.

OK...it is as clear as Washington DC swamp water...

So to use the LOP feature you first press the LEAN button.

Then the EGT display has (in my case) six columns of pretty colored bars that will increase in height as the mixture lever is moved to lean...

Then when the first bar gets to its max height and it just starts to decrease at the top of that particular bar the text will show something like "1-120" meaning that this one cylinder was the first to peak and that it is now 120 cooler than peak.

Did I get this right???

The reason why I ask is that I could not find an explanation in the installation/user manual on how this feature worked and yesterday I was performing the GAMI LOP test and you are supposed to perform the mixture moving to lean sweep in a very slow manner in the span of 3 minutes and as I was doing the slow sweep the digits would go away so there must be some kind of time limit to the feature.

 

[RV8JD]

The reason why I ask is that I could not find an explanation in the installation/user manual on how this feature worked and yesterday I was performing the GAMI LOP test and you are supposed to perform the mixture moving to lean sweep in a very slow manner in the span of 3 minutes and as I was doing the slow sweep the digits would go away so there must be some kind of time limit to the feature.

This is all explained on pages 5-4 and 5-5 of the the SkyView Pilot's User Guide.

 

[DBRV10]

I can help you here.....This is my area of speciality of sorts.

Do a LEAN find test first, rich to lean, and determine the order in which they peak, for example, 6-2-1-3-5-4, and write that down.

Go back rich again, and turn off the LEAN function, just use raw data. Lean slowly, watching for hopefully 6 to peak first, write down the Fuel flow when 6 peaked. Then watch the next one, which should be 2, and so on.....until finally 4 peaks, and that fuel flow is the important one. Subtract the fuel flow #4 from #6 and you will get the GAMI spread.

For 6 cylinder engines you want around 0.5GPH spread or better. For 4 cylinder engines you should aim for 0.3 or better.

When you know your richest cylinder (#4 in the example above), all you will need to do in future is watch #4 and go appropriately LOP on that one.

Lean find functions make great teaching tools, and are good for the exercise I explained above. After that they are near useless, just trust me on that...long story for another day. But you are better off using raw data knowing which cylinder to watch. Otherwise you end up too far LOP and while that does not hurt anything, you will lose speed.

Any questions....ask away.

 

[kellym]

I can help you here.....This is my area of speciality of sorts.

Do a LEAN find test first, rich to lean, and determine the order in which they peak, for example, 6-2-1-3-5-4, and write that down.

Go back rich again, and turn off the LEAN function, just use raw data. Lean slowly, watching for hopefully 6 to peak first, write down the Fuel flow when 6 peaked. Then watch the next one, which should be 2, and so on.....until finally 4 peaks, and that fuel flow is the important one. Subtract the fuel flow #4 from #6 and you will get the GAMI spread.

For 6 cylinder engines you want around 0.5GPH spread or better. For 4 cylinder engines you should aim for 0.3 or better.

When you know your richest cylinder (#4 in the example above), all you will need to do in future is watch #4 and go appropriately LOP on that one.

Lean find functions make great teaching tools, and are good for the exercise I explained above. After that they are near useless, just trust me on that...long story for another day. But you are better off using raw data knowing which cylinder to watch. Otherwise you end up too far LOP and while that does not hurt anything, you will lose speed.

Any questions....ask away.

All well and good, except that it is very common that depending on altitude, power setting, rpm, the cylinders will not necessarily peak in the same order. Yes, the richest cylinder may peak last, but under certain conditions it won't be the richest.
On the IO-540 in your RV10, cyl 3 or 4 is likely to be richest, but not always. Just my experience in over 300 hours of operating that engine.
Lean find is useful if you are staying in same power setting, as you can vary how far you go LOP or how close to peak you choose.

 

[DBRV10]

Well, in 1800 hours of operating ours it has been reasonably reliable, but I will let you in on the secret with the Lycoming engines. The anomaly you observe is not unusual, and it is solved by installing an upper deck system and turbo injectors from GAMI or from Airflow Performance, and picking up the reference air from the airbag.

As for the Lean Find being useful, sure, but if you select 10dF LOP say, and then 10 minutes later find peak from the lean side you will find using raw data that you were way further LOP than you thought. This is not just RV10's, This is Barons, Bonanzas all manner of Cessna and Pipers.

 

[kellym]

Well, in 1800 hours of operating ours it has been reasonably reliable, but I will let you in on the secret with the Lycoming engines. The anomaly you observe is not unusual, and it is solved by installing an upper deck system and turbo injectors from GAMI or from Airflow Performance, and picking up the reference air from the airbag.

As for the Lean Find being useful, sure, but if you select 10dF LOP say, and then 10 minutes later find peak from the lean side you will find using raw data that you were way further LOP than you thought. This is not just RV10's, This is Barons, Bonanzas all manner of Cessna and Pipers.

Well, seems like a lot of money to fix a very minor issue. I was able to balance injectors with just replacing 2 restrictors with the next size down.
My raw data and lean finder indications run pretty close together. Getting a complete set of turbo injectors would not be cheap, having an upper deck system to some central point (airbag?) would be a pain. Key thing is to get the injector bleed holes correctly aligned.

 

[Steveden]

How does that procedure change for those of us who have carburetored, 4 cylinder Lycoming/Continental style engines? I've normally just lean until rough running and the richened until smooth and then slightly richer, probably around 70-90 degrees ROP.

 

[DBRV10]

How does that procedure change for those of us who have carburetored, 4 cylinder Lycoming/Continental style engines? I've normally just lean until rough running and the richened until smooth and then slightly richer, probably around 70-90 degrees ROP.

Most carbs will get LOP.....you may not be describing reality accurately, even though you think you are. Hard to help with little to no info.

But often a bit of carby heat helps too.

 

[Raymo]

> The number when you're in peak mode reflects the order in which it reached peak, not the cylinder number. The cylinder number is locked to the particular graphical slot.

OK...it is as clear as Washington DC swamp water...

So to use the LOP feature you first press the LEAN button.

Then the EGT display has (in my case) six columns of pretty colored bars that will increase in height as the mixture lever is moved to lean...

Then when the first bar gets to its max height and it just starts to decrease at the top of that particular bar the text will show something like "1-120" meaning that this one cylinder was the first to peak and that it is now 120 cooler than peak.

Did I get this right???

The reason why I ask is that I could not find an explanation in the installation/user manual on how this feature worked and yesterday I was performing the GAMI LOP test and you are supposed to perform the mixture moving to lean sweep in a very slow manner in the span of 3 minutes and as I was doing the slow sweep the digits would go away so there must be some kind of time limit to the feature.

It is much easier to do the GAMI lean test provided by Savvy and upload the data. You can create a free account to analyze your data or pay for the Savvy Analysis Pro option for help.

 

[Dynon101]

My original post was ased on how long does the Dynon Lean Of Peak -O Meter monitor the procedure? The reason why I asked this question (it is not answered in the manual) is because I was doing the SAVVY flight test profile where the airplane is operated at a reasonable MAP so that the possibility of engine damage due to detonation was very low and you do a number of ROP to LOP sweeps and each sweep takes like three minutes to accomplish. During that test procedure I would press the LEAN button and start the 3 minute sweep and during the sweep the LOP would stop thinking I was done...so for the SAVVY LOP procedure the Dynon Lean feature was no helpful because it too so long to do the sweep...

My question now is...How fast is the Dynon Lean Of Peak O- Meter?

I just watched the Mike Busch EAA seminar called "Leaning The Advanced Class"...again...well I guess I watched it so many times now I must be the advanced, advanced, advanced class graduate (this just means that I slept through the first three classes).

In the course he discusses not staying too long in the "red box/ red fin" so very long when you do the lean procedure and to not rely on EGT gauge because the procedure takes so long that the engine is operating in the area of 75 F ROP to the point where it is 35 F LOP...on other words watching the EGTs all slowly march up to peak and then each one slowly marches back down is bad because during this whole time the engine is operating in the red box/fin.

So for those of you who lean during the climb...as an example you takeoff at a SL-ish altitude airport and you are climbing to 12,500 for a long cross country flight the idea is to do the "Big Mixture Pull" during the climb...and to do the BMP very quickly...

So the questions with respect to the Dynon Lean Of Peak -O-Meter,,,is,,, how fast is it?

During the climb you get to the point where you want to lean...so the first step is to push the engine LEAN button on the SV display and at that point you do the BMP (Big Mixture Pull) to the position where you remember that the engine likes to be run at that mixture and adjust from there referencing Fuel Flow.

If you do the BMP very quickly (like about 1 second from full rich to the position that you remember that the engine likes...does the Dynon Lean Of Peak O -Meter record the cylinder EGTs so fast or does the indications get blured due to low fidelity?

THANKS for the help

 

[RV8JD]

So for those of you who lean during the climb...as an example you takeoff at a SL-ish altitude airport and you are climbing to 12,500 for a long cross country flight the idea is to do the "Big Mixture Pull" during the climb...and to do the BMP very quickly...

During climb many folks lean using the Target EGT Method. This method keeps you ROP during the climb. See this description:

https://www.advancedpilot.com/course/download/TargetEGT.pdf

 

[GalinHdz]

I've normally just lean until rough running and the richened until smooth and then slightly richer, probably around 70-90 degrees ROP.

^^^^^^^ THIS ^^^^^^^
FWIW: After over 500hrs with my SkyView I have found that if I use this method my engine is at almost the exact same setting as if I had used all the "fancy" EMS numbers. So I no longer even try to use any of the "fancy" EMS methods and just use the old fashion way.
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During climb many folks lean using the Target EGT Method. This method keeps you ROP during the climb. See this description:

https://www.advancedpilot.com/course/download/TargetEGT.pdf

I use this method on every flight and it works great, especially for carbureted engines like mine.

 

[Raymo]

You would not use the Dynon Lean assist during climb, it is intended for use during cruise when < 75% power where detonation will not occur. During climb, lean to maintain 150-200° ROP. You need to know which cylinder peaks first (leanest) and at what temp, then use it as the guide during climb.

I don't use the Dynon Lean assist either but I do use the on screen ROP/Peak/LOP display in cruise.

 

[DBRV10]

Guys.......Your old fashion way is fine, 8000 and above.

I am one of only three current Advanced Pilot Seminars instructors, my friends Walter is dead, John Deakin is alive but cannot do the classes and COVID means even down here we are not running them. But I am happy to help

By the way, Mike and the Savvy stuff........all came from APS, he did the class three times, that is commitment.

The original https://www.advancedpilot.com/redbox.html

Ask me anything, but before we start a few simple rules.

1. Lean Find functions, including Dynon, are limited by mathematical algorithms and probe hysteresis so they make great teaching and training tools and less than optimum in flight every day tools.

2. This 75% or 65% limit is FAKE NEWS......the science dows not support it and has been promoted by TCM/LYC for years because they did not trust you to do things right LOP, yet they expected you to be OK ROP using the same techniques. Go figure!!! That is intellectually void on intelligence for a start, and besides all the possible high stress and danger for turbo machines, it all lives on the ROP side in the +30 to +100dF ROP range. I dont care what you have read....my last statement is irrefutable science backed fact. So do not get hung up on Old Wives Tales.

If you all want to post a bunch of questions, rather than type out hours of text, I can let the questions build up below this post and then I will record one video and answer all of them with thorough answers and explanations and where necessary graphs etc.

I hope that is going to be useful.

David Brown
Advanced Pilot Seminars Australia
davidbrown 'at' advancedpilot.com

 

[Raymo]

Agree, Lycoming and TCM still don't support LOP operations - and older POHs actually recommend running exactly where you should not (red box). I've read (and everyone should) all of John Deakin's Pelican Perch articles (some multiple times). They are fantastic and, as you said, based on actual testing with real engines.

Not sure what you mean by 75% or 65% being fake news. Can you clarify? (Deakin mentions the 75% number for safe LOP operation, as does Mike at Savvy).

 

[DBRV10]

Raymo, you can run 100% LOP, all day long. It is just not physically possible in a NA engine, but if you were to take a TNIO550 and crank the MP to 33" (from its normal 30") and 2700RPM, and set 20 GPH, you would find it runs just fine. It does. This is done on the GAMI test cell.

TN engines in Bonanzas and Cirrus's run LOP at about 83% power all the time. Thousands of them. It is all about controlling ICP and Theta PP. I am glad you like Johns articles. He is not as young as he was when he wrote them but sitting round the dinner table with him talking, its like it was yesterday. Great pilot and great writer and adopted family. I am privileged to have worked with him.

 

[DBRV10]

A week has gone by, and with an absence of questions I assume nobody wants me to produce something, which is fine by me, but I am surprised. There are dozens of OWT's out there that many still believe.

 

[kellym]

A week has gone by, and with an absence of questions I assume nobody wants me to produce something, which is fine by me, but I am surprised. There are dozens of OWT's out there that many still believe.

Most of the presentations I have seen appear to give too much concern about red box for normally aspirated engines. IIRC Walt at one time made a comment that it was very hard to induce detonation on 100LL with a normally aspirated engine and CHTs below 400.
I normally cruise at around 65% with EGTs 0-20 degrees lean of peak and haven't found any issues doing that with my RV10. If closer to 75% I might go to 20-30 LOP, but don't see any benefit of going leaner unless running a turbo. My peak EGTs run around 1490-1520.
Would love your thoughts.
Kelly