Electronic Ignition - seeing through the smoke screen

[Antoine]

I have started this thread to concentrate the info on electronic ignition which caused a creep on two other threads

I understand that Colin was disappointed by the ElectroAir system, seeing no gain at all whereas Phil reported a 12% reduction in LOP fuel burn, consistent with the findings of the CAFEreport linked below.
On the other hand, the MPG Phil is now seeing (136 KTAS running LOP at 8.1 GPH) is significantly lower that that seen by other planes running ROP at the same fuel burn (Hartzell-metal equipped planes do 140 KTAS on 8 GPH)...

I think we need a way to figure out the benefits (if any) despite the smoke screen created by the different airframes. Here an idea. Let us take data points as follows:

WOT, a certain RPM (say 2400?) and a certain MP (achieved by targeting the corresponding altitude).
For example MP = 24 inches which will give about 6000 ft. And 24/24 is easily remembered...

We can then compare fuel flows at peak EGT and LOP (for engines that can do it).

Notice airspeed is not part of the comparison. We can assume that running WOT at the same RPM and MP, our engines should deliver similar power.
We only need to make a distinction between PowerFlow and no PF planes.
If the EI equipped ones show lower fuel flow, we have a proof...

And in case you have not read it - here is an interesting report

http://www.electroair.net/pdfs/ignition_dynamics_II.pdf

So - who will be the first one to do the 24-squared test? (I am about 2'000 miles from my airplane right now)!

Cheers

[Colin]

I will probably be doing an engine test at cruise this week and I will try to try a 24 squared test, too. What altitude do you want that? Or, rather, am I just targeting a particular MP at 5,000?

It's not that I am disappointed. I wanted to get away from the 1950s tractor technology and I have done that. After 20hrs my timing would drift and the engine would sound "thumpy" to me. This has eliminated that. The timing adjusts with the MP sensor (so changes at altitude). In general, the engine runs smoother. The starts seem to be easier (but they were never a huge issue).

I don't run LOP very often. John Deakin (yes, that John Deakin) flew my plane for me and messed heavily with the mixture and said, "I think you have an intake manifold leak, I can't get it to run lean of peak." No mechanic has been able to find a manifold leak.

[Chris B]

I don't run LOP very often. John Deakin (yes, that John Deakin) flew my plane for me and messed heavily with the mixture and said, "I think you have an intake manifold leak, I can't get it to run lean of peak." No mechanic has been able to find a manifold leak.

Hi Colin -

Per this thread (link):

1. Did you run the GAMI test after installing the electronic ignition?
2. Are you running fine wire plugs? Until I switched to fine wire plugs my engine wouldn't run LoP very well.

FWIW, my understanding is that a relatively easy way to confirm (or refute) an induction leak is by running the GAMI test at low and high altitudes (e.g. 2k vs. 8k). An induction leak will cause the peak spread to vary considerably. Unless you have exactly the same leak on all cylinders.

Chris

[Chris B]

Notice airspeed is not part of the comparison. We can assume that running WOT at the same RPM and MP, our engines should deliver similar power.

Hi Antoine -

I may be wrong (happens often... ), but I don't think this is going to get you the results that you want.

I frequently tweak the mixture to minimize fuel flow while holding MP and RPM constant. WOT MP is set by altitude, and we all have constant-speed props! The trade-off is TAS.

So AFAIK, the only meaningful comparison to check the improvement of electronic ignition is a before/after test on the same aircraft under the same conditions (weight, altitude, MP, RPM & TAS), and see what happens to fuel flow. I don't see any other way to empirically measure the added efficiency - if any - provided by electronic ignition.

Chris

[Antoine]

I will probably be doing an engine test at cruise this week and I will try to try a 24 squared test, too. What altitude do you want that? Or, rather, am I just targeting a particular MP at 5,000?

It's not that I am disappointed. I wanted to get away from the 1950s tractor technology and I have done that. After 20hrs my timing would drift and the engine would sound "thumpy" to me. This has eliminated that. The timing adjusts with the MP sensor (so changes at altitude). In general, the engine runs smoother. The starts seem to be easier (but they were never a huge issue).

I don't run LOP very often. John Deakin (yes, that John Deakin) flew my plane for me and messed heavily with the mixture and said, "I think you have an intake manifold leak, I can't get it to run lean of peak." No mechanic has been able to find a manifold leak.

Colin if you do the test here's what I would very much appreciate:
Fly WOT and seek whatever altitude will give you 24 inches of MP at cruise speed.
Do the test at that altitude (2400 RPM, find peak EGT and note fuel flow).
It would be nice if you could post the corresponding flight report.

BTW: if you can't run your engine LOP (whatever the reason), there is not much efficiency gain to be expected from EI. It ONLY showed a gain in LOP operations according to the CAFE Report.

Do you have fine wire plugs? I have had them installed and love them. Worth every penny.

[Colin]

I have fine wire plugs and have since the second year of owning the plane, I love them.

I have not done a GAMI test since being in the plane with Deakin trying to get it to go LOP himself. He said without correcting the induction leak (which, like I said, two mechanics were unable to find) it wouldn't be possible.

I will try to do the test either this week or next. I post all my flight logs when I happen to bring them home.

[Jean]

Antoine, we did a night flight (full moon over the layer ) tonight.
I tried a GAMI test at 30:30 min and a 24/2400 test at 37:00. We were on IFR FPL, so we couldn't descend to get 24 MAP. Not sure it will help you but you can have a look at #5566

[Gasser]

That's a fantastic picture Jean!

[bcocheran]

Antoine, we did a night flight (full moon over the layer ) tonight.
I tried a GAMI test at 30:30 min and a 24/2400 test at 37:00. We were on IFR FPL, so we couldn't descend to get 24 MAP. Not sure it will help you but you can have a look at #5566

Very awesome!

[Antoine]

Lovely pic Jean, thank you. I have watched the same moon from Hurghada Egypt and it was a great idea to go and check it out "on top"

I have a bad connection and it is really hard to figure out what happened in your log file. Will do when I get home Thanks a lot

Antoine