KOSH Fuel savings, Electronic Ignition, Thanks

[sc_acro2]

KOSH Report, G3ignition systems were over whelmed at Airventure 2008 with interest of the new G3ignition, an interfaced-based electronic ignition control system. The reported fuel economy out of the group was 12% better in the RV-6 over the RV-4 that was equipped with standard slick magnetos. Both aircraft were running the same engine configuration. Also in the group of 4, there was a 2% better fuel economy over the other electronic ignition system that was in another RV-4. I had a blast meeting all of you that stop by and would like to thank everyone once again.

Sincerely,

Thomas S.
www.g3ignition.com

[Rocketboy]

I still get 15% better fuel economy from my single LSE plasma III with a Bendix mag, than with dual Bendix mags.

Bob

[osxuser]

Lightspeed uses a mapped profile though right? As I understand it the G3 system is fixed timing?

[RichB]

Originally Posted by osxuser

Lightspeed uses a mapped profile though right? As I understand it the G3 system is fixed timing?

LSE FAQ says...
"The Plasma II series is a single spark system which has a fixed spark duration at all rpm.
The Plasma III has a dual output stage which provides a continuous spark for about 20 degrees of crankshaft rotation at all rpm."

G3i product page says...
"The G3i interfaces aircraft magnetos with (MSD) ignition systems. In turn compliments the synchronized firing event in all naturally aspirated and supercharged Lycoming & Continental engines. MSD ignition uses multiple sparking technology, which last for 20° of the crankshaft rotation."

So yeah, LSE Plasma III looks comparable to G3i in regard to spark duration, although LSE appears to have control over the timing (via mapping MAP and RPM, and start retard) while the G3i looks to be triggered by the mag timing (also with optional start retard). After reading their sites and manuals, the implementations look waaay different though...

[sc_acro2]

Osxuser,
Yep, the G3ignition timing is fixed for naturally aspirated engines and it works very efficient. It is the multiple discharges that completes the burn effectively. The benefits obtain from the mapped advance curve in aircraft application is not that critical. With most electronic aircraft applications, when the power settings are above 70%, there is no advance from the base timing.
Thomas S.

[Geico266]

What is nice about this set up is cost, and if it fails you still are running on the Slicks. The MSD ignition module works well on Lycomings. I had one on my -3 and removed it due to the age of the Bendix mag it operated. I'm looking at this set up closely as it fires BOTH mags with the hotter spark.

[frankh]

So once the charge is lit...its lit..Why does this "continuous spark" make any difference?..I don't see why it makes any difference how long the spark is

Seems from thinking about it you want vairable timing so the max cylinder pressure always occurs at the ideal point (30 deg after TDC I believe)...The higher you go the thinner the air and the slower the flame front...

Sooo in theory you need to advance timing with reduced MP.

Can someone explain this??

Frank

[David-aviator]

Originally Posted by frankh

So once the charge is lit...its lit..Why does this "continuous spark" make any difference?..I don't see why it makes any difference how long the spark is

Seems from thinking about it you want vairable timing so the max cylinder pressure always occurs at the ideal point (30 deg after TDC I believe)...The higher you go the thinner the air and the slower the flame front...

Sooo in theory you need to advance timing with reduced MP.

Can someone explain this??

Frank

I can't but perhaps this statement from the Electorair web site will do it. The peak pressure point is 11 degrees after TDC according to EIS.

On a traditional dual magneto system, both magnetos are timed to fire at 25 degrees before Top Dead Center (TDC). When starting the engine, the ignition switch grounds the ?P? lead to the right magneto, stopping it from firing. Meanwhile, the left magneto with the impulse coupling can still fire. The impulse coupling causes the magneto to fire at TDC, and will continue to fire at TDC until the engine reaches about 200 RPM. At this time, the impulse coupling disengages and the magneto falls back to firing at 25 degrees before TDC. Once the ignition switch is released from the start position, the right magneto also begins to fire. From now on, no matter what the RPM, power setting, or altitude the engine spark timing will remain at 25 degrees before TDC.

At any altitudes, a cylinder on the intake stroke draws in fuel and air. At lower altitudes, on the compression stroke (as the piston moves up) at 25 degrees before the piston reaches the top of the cylinder (TDC), the spark plug fires lighting the air/fuel mixture. The objective is to reach the peak pressure point (as a result of igniting the air/fuel mixture) by the time the piston reaches 11 degrees past TDC.

As altitude increases, thinner air reduces the oxygen available for the proper fuel-air mixture creating more space between the air/fuel molecules. When the spark plug fires at 25 degrees before TDC, the thinner air/fuel mixture will burn slower. Therefore, the peak pressure point occurs much later than 11 degrees past TDC, and hence there is a loss in power. By advancing the timing based on RPM and atmospherics, the peak pressure point can be maintained much closer to 11 degrees after TDC. This can only be done with an electronic ignition system and is best done with an Electroair Ignition System (EIS)!

[sc_acro2]

Hi Frank,

Here is a good link to MSD that gives a description of Multiple Spark Discharge.
http://www.msdignition.com/page.aspx?id=3356
Simple question, your engine runs better on 2 mags than 1 correct? 2 sparks are better than 1 spark, ok, lets multiple discharge.each plugs now get 2 to 3 sparks per firing event. That a total of 4 to 6 sparks. With the primitive/poor fuel atomization we have in these low RPM engines after the first fuel/air ignition spark take place, there is plenty of air/fuel mixture still not ignited. As it passes by the spark plug during the combustion cycle, the multiple sparks ignites it. A more complete burn = more power = better fuel economy.
Advancing the timing is not a bad thing unless it is a run away and stuck @ full advance or under starting conditions. Under testing and comparing various systems with advance features we just didn’t see a whole bunch of benefits for the complications and possibly detonation failures to follow.

Hope this helps,
Thomas S.
www.g3ignition.com

[frankh]

But running on just one mag effectively retards the timing.I.e the peak pressure occurs later..Hence it does not make as much power..with two plugs your lighting the fire from both sides.so the peak pressure will occur sooner than if you only light it from one side...I.e with a single plug.

The plugs are in a fixed position..in the cylinder head..This does not seem logical to me..But if you have data then its hard to argue with.

Sometimes i hate being an engineer!...

Frank