My experience with the ElectroAir ignition upgrade

[waynemcc999]

Wow, Antoine... superb stuff! And I love the analytical nature (I'm an engineer ).

Climb: I'll definitely give 2550 rpm and 80 KIAS a try. Your approach makes total (and numeric) sense.

Cruise: I'll experiment with this further. No doubt, I've experienced a good number of times the corked nose wheel problem. I'll check, but I do believe the rudder trim tab is bent a bit.

Question: often in cruise, the "ball" (surfboard) is displaced off to the right. Does this say something about the corked nose wheel? or too much/too little rudder trim tab?

And I also have a very good feeling about the fine wire plugs.

Thanks again for sharing your experience, configurations, and wisdom!
Wayne

[wickman]

I purchased #40.1091 in December and it came with an ElectroAir. From my limited experience with it, you should just tear out the AFM cruise performance tables and throw them in the trash because they are now worse than useless.

I have Tempest fine-wire plugs on the mag side and IIRC massive electrode plugs on the EIS. Taking the recommended power settings from the AFM, you'd expect 75% 4500' cruise to be 2400 RPM / 24.3" MAP / 9.5 GPH to give you best economy. The reality? Peak EGT is somewhere around 8.5 GPH. I routinely have to run about 1-1.5 GPH leaner than the AFM to keep the CHTs cool. Anything in the AFM runs the CHTs way too hot with my setup.

Take the following flight for example:
https://www.diamondaviators.net/reports/flights/9416

Using 75% settings, the CHTs are very happy at 310-330 at 8.2GPH but will only give you ~137 KTAS. Bump it up to 8.7 and you get ~143 but the CHTs jump to 340-380. In order to get the CHTs down, I have to go significantly ROP, which seems pointless with the EIS.

As an aside, it's become clear in my limited flying that evenly distributed cylinder mixture in the IO-360's ordinarily narrow LOP regime is super important. On my engine, the fuel injection on cylinder 1 is a bit leaner than 2-4, but enough so that by the time I get 2-4 barely LOP, cylinder 1 is running rough and EGT1 goes haywire. It seems this can be a huge hurdle getting the sort of fuel economy that the EIS promises. So until you have perfectly balanced injectors, you may as well run ROP.

I'm meeting with my mechanic on Thursday and will probably replace the EIS plugs with fine wires. Once I get some more data, then we'll start investigating mixture distribution and hot CHTs.

All this being said, I've loved the plane so far and is probably the nicest DA40 I've flown (this is probably why I bought it.) The EIS has just thrown a wrench into understanding how the heck it's supposed to behave!

~brian

[BlackMammoth]

#1 - The fine wire plugs are better, and will improve your ability to fire leaner mixtures.

#2 - Do a "GAMI Lean Test" http://www.gami.com/gamijectors/leantest.php

#3 - The performance figure in the AFM are not very useful.

[Chris B]

The fine wire plugs are better, and will improve your ability to fire leaner mixtures.

This may be blindingly obvious to everyone else. But one of the things that the APS course helped me finally understand is why fine wire plugs help LOP.

The mixture inside a cylinder is *not* a monolithic fuel:air ratio. The short-lived and turbulent mixture actually has relatively uneven fuel:air ratios. ROP almost any spark will find a burnable mixture, since there is excess fuel and the mixture must be super-rich before it won't ignite.

But LOP - by definition - more of the cylinder contents have too little air to support combustion. The probability that a spark contacts an area with "burnable" fuel:air depends on spark size and duration. More vigorous and longer sparks improve the chances for ignition.

Fine wire plugs create a larger spark "bubble" that has a better chance for ignition LOP. The even-larger-and-longer spark from the Electroair ignition further improves the odds.

Chris

[Antoine]

Taking the recommended power settings from the AFM, you'd expect 75% 4500' cruise to be 2400 RPM / 24.3" MAP / 9.5 GPH to give you best economy.

Using 75% settings, the CHTs are very happy at 310-330 at 8.2GPH but will only give you ~137 KTAS. Bump it up to 8.7 and you get ~143 but the CHTs jump to 340-380.
~brian

Hi Brian, thanks for the above. Very interesting but you got me confused. I picked the two sentences which I don't understand (75% and 8.2 GPH?).
I am not good at engine settings down low ( I always cruise around 9 K if I can).

143 KTAS at 8.7 GPH this low means you have a very fast DA40.

In the context of an IO-360 M1A in a DA40 (and only in this context) I am not a fan of very low CHTs.
I think our engine needs between 330 and 360 (cruise) and 400 (climb). Don't know how if/much this affects longevity, but when I owned my DA40 I was pampering it in general and still running the engine like this for 1000 hours. Never had any fouled plugs and it was a very very smooth running baby.

Wayne, regarding corked nose wheel, here a recipe to find out if you "have it" or not:
Remove nose wheel fairing and trim tab. Stow away VERY carefully (or buy new screws and trim tab, ask me how I know!)
Test fly: if speed goes UP by approx. 1 knot - you have the problem
If speed goes down by 3-4 knots you don't.

I don't know if all DA40s react the same, but what I noticed is that there is a relatively narrow speed band where the DA40 flies coordinated at a given trim tab setting. With no trim tab and a straight nose wheel this is between 145-150 KTAS at altitude. Slower needs right rudder input (as in the climb) and faster needs some left rudder.

[blsewardjr]

Electroair.pdf

(1.51 MiB) Downloaded 67 times

I recently was talking to a shop doing a DA40 engine replacement and they mentioned they would be adding DUAL Electroair ignitions, which they said had recently been approved. There's nothing on the Electroair website, nor to my knowledge has there been an announcement at Oshkosh. However, the latest edition of the Sport Aviation does contains an add for a dual installation.

[rwtucker]

The brochure mentions backup power. Does anyone know about that?

[BlackMammoth]

Yes, you have to provide a backup power source...

Contact https://smoothpowerllc.com/ for further information.

[rwtucker]

Thanks Phil. The company added a link stating that they received approval for dual installations April of this year but they have not had time to put detail on their website. I do not see any specs other than the fact that a battery is required. Are we talking about a 7 amp sealed lead acid, a 10 amp LiFePO4, or ??? And where is it located? I sent an inquiry and will post when I learn more.

[BlackMammoth]

I haven't done this and don't intend to... however I believe that the regulations require a 60 minute reserve power source if using a battery, or a standby alternator that may not use more than 80% it's rated load capacity.

Everything will need to be certified so I expect it be a pricey option. Electroair was talking about bringing a solution to market to address the backup power issue but I haven't seen what it looks like yet.