Lean Of Peak -O-Meter

Dynon101

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Mar 5, 2016
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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

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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

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> 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

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Dec 17, 2017
Messages
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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

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Jun 15, 2008
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Brisbane, Qld. Australia
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

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Sep 29, 2013
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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

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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

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Sep 29, 2013
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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

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Jul 10, 2019
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Carnation, WA
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

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Jun 15, 2008
Messages
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Location
Brisbane, Qld. Australia
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

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Apr 25, 2016
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Richmond Hill, GA
> 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.
 
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