Thoughts of Electronic Ignition

[kevinsky18]

I'm looking at the Light Speed Plasma Electronic ignition for my IO-360-M engine with 9.2:! compression pistons.

Thoughts on Plasma II vs III and direct crank verse Hall effect?

Any thoughts on Dual verses single Electronic Ignition? In the event of an alternator failure in a dual ignition system how long will a battery keep the engine running?

[walter]

If you don't have a vacuum pump, why not install a backup alternator.
Then your worries are a bit less. Primary alt, secondary alt, then battery.
Unless your battery falls out of the plane you should be good with almost
any choice of EI. You can even make that more robust with dual P-mags. Although
lately there seems to be some aversion to the P-mags due to their recent
introduction and not insignificant problems, which I believe (hope) they will
fix in due time. Just thinking outloud.

[Captain Avgas]

Originally Posted by kevinsky18

Thoughts on Plasma II vs III and direct crank verse Hall effect?

Any thoughts on Dual verses single Electronic Ignition? In the event of an alternator failure in a dual ignition system how long will a battery keep the engine running?

The crank sensor is slightly more reliable than the Hall Effect but has a longer installation time.

The Plasma III has a longer duration spark and is therefore more efficient at igniting the fuel mix. This can be particularly valuable if running Lean of Peak when the mix is harder to ignite. On the down side the longer spark erodes the spark plugs faster and puts more stresses on the high tension wires and coils. Therefore the mean time between failure is greater on the Plasma II than the Plasma III.

The time that a battery will keep a dual system running depends on the amp/hour capacity of the battery you choose.

Personally I'm opting for a Lightspeed Plasma II on one side and a magneto on the other side (and going with a crank sensor). That's the most conservative option at this particular stage and I opted for that because I intend long flights over water.

If I was opting for dual Lightspeeds I'd certainly want a back-up alternator on the accessory case. That's the only way you can ensure that the engine will keep running until all the fuel is used up.

[Walt]

Originally Posted by Captain Avgas

The crank sensor is slightly more reliable than the Hall Effect but has a longer installation time.


Personally I'm opting for a Lightspeed Plasma II on one side and a magneto on the other side (and going with a crank sensor). That's the most conservative option at this particular stage and I opted for that because I intend long flights over water.

If I was opting for dual Lightspeeds I'd certainly want a back-up alternator on the accessory case. That's the only way you can ensure that the engine will keep running until all the fuel is used up.

I agree with the above, especially until the rest the electrical system have proven itself. I started out the same as Mr Avgas but a year later pulled the mag and installed the second LSI III (first was a II so now I have a II and a III). I definately noticed an improvement in smoothness and can now run LOP (I have a carb) with no problem which I do regularly. I also run a back up vacuum pad gen from B&C. A little over 2 yrs flying and just about to hit 600 hrs with zero problems (about 200 hrs with the dual LSI). I switched from the "Hall effect" to the crank sensor as well for reliability reasons (no moving parts now) when I installed the 2nd system.

[chaskuss]

Originally Posted by Walt

snipped
I switched from the "Hall effect" to the crank sensor as well for reliability reasons (no moving parts now) when I installed the 2nd system.

Walt,
I am facinated by your ability to run lean of peak with a carb. Could you please give us some more info on your experiences in this area?
Charlie Kuss

[Walt]

It's really easy, I just keep leaning until the richest (coldest egt) is about 10deg LOP and the hottest is about 50deg LOP. EGT's get within about 50 degrees of each other (they actually get closer as I go on the lean side). With the dual EI the engine does not get rough, with the single EI it would start to get rough anything past peak but with the dual there is no roughness at all. I can actually keep leaning and feel the power falling off but it's still smooth. For ref my normal power setting is around 2350/20" which gets me around 6.5gph at about 50-55% power I figure (close enough for me). Average speed at this setting is around 135 Knots. Anything below 65% I always run at peak or LOP these days. Over 75% I still run ROP but this only during take off and climp, once I'm at altitude I pull the power and the mixture back.

[Captain Avgas]

Originally Posted by Walt

I started out the same as Mr Avgas but a year later pulled the mag and installed the second LSI III (first was a II so now I have a II and a III). I definately noticed an improvement in smoothness and can now run LOP .

Hi Walt, of course it might be possible that the improvement you have experienced in smoothness arises from the installation of the Plasma III with the longer duration spark (rather than the fact that you have dual units now).

What happens when you switch off the Plasma II in flight....do you notice any difference or is it just along for the ride.

[Walt]

No it's not like the mag which was along for the ride, now if I switch off either LS I notice the difference immediately both in smoothness and higher EGT's.

[Captain Avgas]

Originally Posted by Walt

No it's not like the mag which was along for the ride, now if I switch off either LS I notice the difference immediately both in smoothness and higher EGT's.

Walt, you're a great source of information on this topic. Next question. When you're running LOP (or ROP) and you switch off one EI, can you notice any difference in performance between the single Plasma II and the single Plasma III. You're the only person I know with one of each to be able to compare.

Cheers Bob

[mburch]

Originally Posted by Captain Avgas

The Plasma III has a longer duration spark and is therefore more efficient at igniting the fuel mix. This can be particularly valuable if running Lean of Peak when the mix is harder to ignite. On the down side the longer spark erodes the spark plugs faster and puts more stresses on the high tension wires and coils. Therefore the mean time between failure is greater on the Plasma II than the Plasma III.

That's very interesting - I hadn't heard that before. I went with a single Plasma III instead of a II on my engine, solely based on the idea of "well, it's not that much more expensive and everybody says it's better, so why not?" I guess I'll have to keep an eye on it.

Walt - Let us know which one breaks first, Plasma II or III...

mcb