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EMS setting for D180 fixed Sensenich 2600 rpm (Read 143 times)
Apr 30th, 2018 at 5:48pm

rjcthree   Offline
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A/C is an RV-9A with a O-320, Sensenich fixed prop limited to 2600 RPM and a D180. For best % power accuracy, what should the recommended green to yellow and yellow to red setting for tach be? This is not equipped fuel flow, so it sees MAP, altitude and altimeter, and Tach.

Forgraphical reasons, I would like the yellow to red to be 2600, but Im not sure if that will skew the results.

Im not sure I believe what I have now, in that 2300rpm, 20.6 in MAP, 5460 p alt/5240 d alt, 6c OAT was showing 64% on the display. I believe that to be closer to 50%-55% from the Lyc charts. I was showing 132kt indicated, 142kt TAS at the time.

Thanks, Rick
« Last Edit: Apr 30th, 2018 at 5:49pm by rjcthree »  
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Reply #1 - May 1st, 2018 at 5:21pm

Dynon Avionics   Offline
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There are two things you can tweak to affect the percent power calculation. One is the yellow/red setting (redline), although that should really be set to the manufacturer's recommendation. The other is the horsepower rating in setup. We should have named this "adjustment factor" or something along those lines, because sometimes people don't like putting a number in that field that feels "wrong", even if then they have a percent power that isn't matching expectations against the chart. But basically, it affects the virtualized the table that produces the % number. It's admittedly the easiest to tune when you have a fuel flow sender, because you can use the LOP/ROP detection, along with that number, two ensure that the LOP/ROP changes over at your peak EGT values. When that's right, the % power also ends up being right too. Note that without a fuel flow sensor, you won't ever get accurate % power on the LOP side.
 

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Reply #2 - May 1st, 2018 at 5:28pm

rjcthree   Offline
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Thank you for the reply. Setting yellow/red is what I had read earlier as a key element. Since what I think is happening is the % power is reading higher than actual by 10%-15%, what is your best guess about how far and in what direction to move the adjustment factor? Im really not worried about LOP without fuel flow sensor.  Thanks.
« Last Edit: May 1st, 2018 at 6:30pm by rjcthree »  
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Reply #3 - May 7th, 2018 at 5:02pm

Dynon Avionics   Offline
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So just an update here - the horsepower number really only affects the way that the ROP/LOP detection works. Because you don't have fuel flow, that number doesn't affect anything. The redline does affect horsepower, but everything should line up if you follow the manufacturer's red line. Incidentally, we ran your numbers through a power calculator manually, and it lined up perfectly. So we think you're getting the power calculation we'd expect.
 

Please do not use Private Messaging on form to contact. For private support:
Email: support at dynonavionics dot com
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