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lr172

Well Known Member
I have a Dynon 120 EMS and have been experimenting with the Leaning mode, but have a question. I know that once a cylinder peaks, the Dynon will convert the reading from actual EGT to a difference amount from the peak temp. However, I sometimes will go lean then rich again. Sometimes for experimentation and sometimes because I went too lean. Does the Dynon go back to actual EGT once it hits peak and goes ROP or does it stay as a differential reading? It seems that I am seeing some cylinder as ROP and some LOP. However, every number has a - in front of it. If it stays as a differential, how do you know if the indication is LOP or ROP?

I have a carb'ed engine, so I don't have a tight spread.

Thanks,

Larry
 
The GRT will stay with the "difference" value, and that makes sense. I don't know how the EMS would know which side you are on.

As for YOU knowing, do the values increase or decrease when you go rich or lean? If you are LOP, then leaner mixtures will increase the differential as it gets cooler. If you are ROP, then going leaner will reduce the differential as you get hotter (closer to peak).
 
It stays in deferential mode. After peak any movement of the mixture will lower the temp. Rich or lean of peak the temp goes down.

Bob burns
N82rb rv-4
 
Toobuilder said:
The GRT will stay with the "difference" value, and that makes sense. I don't know how the EMS would know which side you are on.

As for YOU knowing, do the values increase or decrease when you go rich or lean? If you are LOP, then leaner mixtures will increase the differential as it gets cooler. If you are ROP, then going leaner will reduce the differential as you get hotter (closer to peak).
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It's apparent when they first go lean. After changing to the differential value, the numbers increase as I lean. It's when I richen a bit from LOP that I struggle. I have not paid enough attention to all four numbers at the same time. I suppose if I concentrated a bit more while leaning/richening it would be a bit easier to know which cylinders were on the lean side and which on the rich side. I have a 100+ spread from leanest to richest and 100 LOP is around the best I can do. SO, a cylinder or two is near peak and it would be nice to be able to glance down and know which side of peak it is on. But now that you point it out, after the first peak crossing, I understand that the EMS can no longer keep track of which side of peak it is on.

Larry
 
n82rb said:
It stays in deferential mode. After peak any movement of the mixture will lower the temp. Rich or lean of peak the temp goes down.

Bob burns
N82rb rv-4
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That has not been my experience. For example, I lean until my leanest cylinder is 100* LOP; EMS shows -100 (decrease EGT post Peak). I then richen a bit and it lowers the number to -50 (increase in EGT). I lean again and it raises the number to -75 (decreases EGT).

Larry
 
lr172 said:
That has not been my experience. For example, I lean until my leanest cylinder is 100* LOP; EMS shows -100 (decrease EGT post Peak). I then richen a bit and it lowers the number to -50 (increase in EGT). I lean again and it raises the number to -75 (decreases EGT).

Larry
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That's exactly how it works. It show the difference from peak. You lean it past peek it is running 100 degrees lower than peak. If you richen it the egt goes up and the difference from peak decreases. If you lean from that egt decreases and the difference from peak increases.

Bob burns
Rv-4 n82rb
 
The logic is pretty simple: For each cylinder, we keep track of the highest temperature we have seen since lean mode was entered. Once the temperature is 5 degrees less than the max, we show it as a difference. This is done per-cylinder.

The only way the system will stop showing a temperature difference is if the temperature gets higher than the peak. Once the new higher temperature starts going down, it will go back to the differential mode. If you leaned slowly, and haven't changed MAP, RPM, IAT, or altitude then this shouldn't really be possible.

We do show ROP or LOP on the bottom of the screen, as well as a flow difference. The LOP/ROP is for the whole engine, and is based on the fuel flow from when the last cylinder peaks. If the current flow is less than this then you are LOP and vice versa. We also show the "spread" which is the difference in flow from the first cyl to peak and the last, telling you how balanced the engine is.

It is theoretically possible for us to track ROP/LOP based on fuel flow on a per cylinder basis, but we currently don't do that.
 
dynonsupport said:
The logic is pretty simple: For each cylinder, we keep track of the highest temperature we have seen since lean mode was entered. Once the temperature is 5 degrees less than the max, we show it as a difference. This is done per-cylinder.

The only way the system will stop showing a temperature difference is if the temperature gets higher than the peak. Once the new higher temperature starts going down, it will go back to the differential mode. If you leaned slowly, and haven't changed MAP, RPM, IAT, or altitude then this shouldn't really be possible.

We do show ROP or LOP on the bottom of the screen, as well as a flow difference. The LOP/ROP is for the whole engine, and is based on the fuel flow from when the last cylinder peaks. If the current flow is less than this then you are LOP and vice versa. We also show the "spread" which is the difference in flow from the first cyl to peak and the last, telling you how balanced the engine is.

It is theoretically possible for us to track ROP/LOP based on fuel flow on a per cylinder basis, but we currently don't do that.
Click to expand...

Thanks for the detailed explanation above. In addition to the LOP/ROP + Flow indication at the bottom, there is also a LOP/PEAK/ROP indication that appears next to the % power indication. Can you explain how it determines which state that it presents. I assume it is different as it appears even when not in LEAN mode.

Thanks,

Larry
 
dynonsupport said:
Larry,
The LOP indication next to the % power is one of the most uniqute features of the Dynon engine monitors. When configured correctly, it tells you if you are LOP or ROP completely automatically without any other interaction required by the pilot.

We have a good article about this:

http://preflight.dynonavionics.com/2014/02/did-you-know-percent-power-dynon-way.html
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Can you provide some guidance for "configuring it properely?" I am guessing it is tied to the HP setting but there may be other factors or ways to adjust the HP setting to match my engine beyond matching it to the HP on the data plate.

Larry
 
It should be based on HP at redline rpm and 30" MAP, so a decrease in RPM and MAP off these redlined will calculate a percent HP. Dynon can explain whether they use this or just a fuel flow compared to max, but the rpm/map would be a better format.
 
Is my 180 Broken?

dynonsupport said:
Larry,
The LOP indication next to the % power is one of the most uniqute features of the Dynon engine monitors. When configured correctly, it tells you if you are LOP or ROP completely automatically without any other interaction required by the pilot.

We have a good article about this:

http://preflight.dynonavionics.com/2014/02/did-you-know-percent-power-dynon-way.html
Click to expand...

Hi Dynon, I've got a Dynon 180. In the "lean" mode, it still shows me either ROP or LOP. And the % LOP/ROP used to to show me either %LOP or % ROP. But now it always shows % ROP even when my EGT's have peaked and started to drop as I pull the mixture back. It's broken, correct?
 
Don,
Is your fuel flow working? That is required and needs to be accurate for the % power to work.

The % power is just math inside the processor. If it's not working, your MAP, RPM, Altitude, OAT, or fuel flow is broken.
 
lr172 said:
Can you provide some guidance for "configuring it properely?" I am guessing it is tied to the HP setting but there may be other factors or ways to adjust the HP setting to match my engine beyond matching it to the HP on the data plate.
Click to expand...

Start with the data plate HP number. Then, you need to use the EGT peak to determine when you are LOP or ROP while calibrating the automatic system to see if it shows LOP early or late.

If you are getting an auto Lean-of-Peak indication that is coming on too early, before the engine actually peaks while leaning, lower this number. It is not meant to be a measure of actual horsepower produced, as engines that are more efficient will act as if they are lower horsepower in the calculation. This will be particularly true if you are running a higher compression ratio than the stock charts are based upon.
 
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