Engine parameters Lean-of-Peak

[Sportsman7064]

Dynon (and others),

I'm getting started using my Skyview system to assist in operating LOP.  So far, so good.  Several other pilots at my local airport (not using Dynon) warned that some of the engine parameters that the system calculates, such as % Power and Horsepower, might not be accurate when running LOP due to the way the software makes those calculations.  Is this the case with the Skyview system?

Thanks

Russ

 

[Sportsman7064]

I think I've located the answers I was looking for in the this thread from a while back. (Thanks, mmarien! Lots of good learning on the topic)

There is some discussion on %power and LOP here:

dynonavionics.com/cgi-bin/yabb2/YaBB.pl?num=1409279759

Russ
RedGold TMX IO-360, dual Plasma II+, Sportsman 2+2

 

[Carl_Froehlich]

Don't worry about % Power indication at it is only that, an indication. This is not what you use to operate LOP.

The EMS has an exceptionally accurate "Lean" function for you to use. Do a few runs at different power settings and altitudes with the EGTs all -10 degrees or more LOP. Download the data and do a table for each cylinder fuel flow when EGT peaks. The difference between first to peak and last to peak (GAMI spread) should be less than 0.5 GPH. If not, contact AirFlow Performance for assistance in swapping out injectors. On my IO-540 I started out with a GAMI spread of 1.2 GPH and the engine was unacceptably rough operating LOP. I ended up changing four of the six injectors and now my GAMI spread is 0.1 GPH and the engine is as smooth LOP as ROP. At $21 each for different size injectors this is dirt cheap.

I operate 90% of the time LOP and enjoy CHTs 40 degrees cooler than the same power setting ROP, and a huge fuel savings. Once you have the cylinders balanced you will learn the fuel flow you want for each power setting.

Carl

 

[dynonsupport]

Carl and Russ,
The EMS % power function is also exceptionally accurate, and Dynon's % power is the only EFIS out there that has accurate % power numbers when LOP.

The great thing about this is that you can use it to set LOP powers. If you're 75% power ROP and pull the mixture, you'll see that you're now 70% or less while LOP. On top of this, it will show you when your are LOP or ROP without any manual work.

For a lot of pilots, this means they no longer even use the manual LEAN function.

 

[Carl_Froehlich]

Carl and Russ,
The EMS % power function is also exceptionally accurate, and Dynon's % power is the only EFIS out there that has accurate % power numbers when LOP.

The great thing about this is that you can use it to set LOP powers. If you're 75% power ROP and pull the mixture, you'll see that you're now 70% or less while LOP. On top of this, it will show you when your are LOP or ROP without any manual work.

For a lot of pilots, this means they no longer even use the manual LEAN function.

Thanks for the feed. I note however that operating experience consistently has the EMS showing LOP before the engine reaches LOP. Not by much, but still off.

Carl

 

[thibault]

The manual tells you how to "fine tune" this behavior by changing the engine horsepower setting on the setup page.  It is a trial and error process.  Go read and try it.

 

[preid]

The manual tells you how to "fine tune" this behavior by changing the engine horsepower setting on the setup page

Specifically (install manual 7-62)
Set it to the engine manufacturer's rated HP for initial usage. You may need to adjust this number in order to get all calculations working correctly.
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.

 

[Sportsman7064]

Thanks, Carl and Dynon. My GAMI spread is 0.2 GPH. The whole injection system is Airflow Performance. I haven't had to fine tune the ROP - P - LOP indication, but I don't have a high-compression engine.