Electronic Ignition - seeing through the smoke screen

[Rich]

Chris, I crunched my GAMI test data with your X-Y chart and polynomia order 4 trick.
It looks like my GAMI spread is less than 0,3 GPH.
Thank you for iniating me to Excel's magic
BTW what does order 4 stand for ?

Chris answered the question of 4th order polynomial. It means that the highest exponent used is 4. Basically it's a curve-smoothing technique where a bunch of data point sets you have are used to deduce an equation of the form a(x^4)+b(x^3)+c(x^2)+d(x)=y,
where a,b,c,d are deduced from several pairs of known x,y data points that you have.

FYI, such equations are typically used to convert the millivolt output of thermocouples to degrees C, F, or whatever. But those are often 5th or 6th order polynomials. Such polynomials are defined for the various known thermocouples.

[Jean]

Chris, I crunched my GAMI test data with your X-Y chart and polynomia order 4 trick.
It looks like my GAMI spread is less than 0,3 GPH.
Thank you for iniating me to Excel's magic
BTW what does order 4 stand for ?

Chris answered the question of 4th order polynomial. It means that the highest exponent used is 4. Basically it's a curve-smoothing technique where a bunch of data point sets you have are used to deduce an equation of the form a(x^4)+b(x^3)+c(x^2)+d(x)=y,
where a,b,c,d are deduced from several pairs of known x,y data points that you have.

FYI, such equations are typically used to convert the millivolt output of thermocouples to degrees C, F, or whatever. But those are often 5th or 6th order polynomials. Such polynomials are defined for the various known thermocouples.

[Chris B]

Chris, I crunched my GAMI test data with your X-Y chart and polynomia order 4 trick.
It looks like my GAMI spread is less than 0,3 GPH.
Thank you for iniating me to Excel's magic
BTW what does order 4 stand for ?

Excellent!

4th order simply means that the largest exponent is 4. IOW, x^4.

Practically, it means that the curve can have sharper transitions.

Chris

[Colin]

I was not trained well to use the "LEAN" button on the G1000 and I find my habits hard to break. (The salesman just showed the peak-finding operation, then showed that he usually just richened until it was 75 degrees rich of peak. We were 5,500 MSL SMO-HND at the time.)

I now know that I could run at peak EGT over 8,000 feet with impunity. I have yet to do that.

Maybe I'll try that after the annual, when I know it is all good and tight under the hood.

[Antoine]

Hi Colin

Have you had a chance to try a test at peak EGT around 8000-10000 FT? This data would really help as I'd like to pull the trigger on this ElectroAir install.

Also: can you tell us how the install went and whether there are any gotchas?

Many thanks

[kjmeyers1]

I had the Electroair installled a few weeks ago. My Diamond Service center Alpine Air at KGOO did the install. They did a very professional installation. They did a Gami test before and after. They are supposed to scan the notes and send them to me and I can make them available. My initial flights have me thinking there is a very modest improvement in fuel burn, but the engine is clearly running smoother and I can now run the engine LOP where it was impossible before. I had my mechanic run the Gami test to see if we could install the Gamis and I was in good shape in that department. At the last annual I had Alpine put in the Fine Wire plugs.

I was putting along the other day 118kts TAS at 4500 feet burning 7.1 gallons per hour. That's kinda fun.

As far as the physical install, everything was installed under the cowling except the controller box which was installed under the right pilots dash half way or so between the front of the dash and the firewall. There also is a EIS on/off switch that needs to be installed and my guy installed that near my master switch. He also had a guy come over and etch EIS over the switch and paint in the EIS in white. It looks like it came that way from the factory. It's amazing when you do the mag check and you turn of your existing magneto and your RPMs drop 30 or so and then when you switch to the magneto and turn off the EIS and you watch the RPMs drop 175.... Overall I'm very happy, it's nice to be able to run LOP.

[Antoine]

Thank you Kenneth. much appreciated. Please keep info flowing back.

Do you have an opportunity to fly high (9-10 K) - this is where the EI is supposed to shine, as it would not advance ignition much at the altitude you reported about.
I am being told it saves 1 GPH and gives more power at altitude.

Safe flying

[kmeyers1]

I haven't been up at that altitude yet with the electroair. My airport sits at 3100 feet in the foothills of the Northern Sierra Nevadas so I will be going higher. The weather hasn't been great since the install and I'm not instrument rated yet....

[Antoine]

I understand absolutely.

As I said above, I believe the EIS will only really shine when you fly high, because the increased ignition advance only becomes significant at altitude.
At lower altitudes you will only benefit from the high energy and long duration spark which as you noticed provides LOP capabilities and generally a smoother running engine.

Once you have an opportunity to get to altitude I would really appreciate it if you could test the system with wide open throttle, about 2500 RPM and peak EGT (this is where I have a lot of data points to compare with). I expect that you should be saving about 1 GPH around 9'000 ft and getting a measurable speed increase above 10'000.

But safety first - I have been waiting a long time for this PIREP so please do not take any chances just to be friendly

Do you have a pic of the EIS switch? This looks like a very good shop you have there.
Thank you!

[kjmeyers1]

Hi Atoine,

I'll post some pics this weekend. I'm supposed to see some decent weather. If I do I'll get up to 10,000.

Sincerely,

Ken