Van's Air Force
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One P-mag or one Light Speed CDI ignition?
- Thread starter bardample
- Start date
LSE Plasma
Why the angry face?
Making these decisions and many others were the most enjoyable parts of
building my airplane.
Can't tell you about Pmags but I have had great success with one LS ignition
and one magneto.
Electronic ignition for the top plugs and magneto for the bottom plugs.
Benefits are: easy starting, variable timing for maximum efficiency and
no moving parts.
Why the angry face?
Making these decisions and many others were the most enjoyable parts of
building my airplane.
Can't tell you about Pmags but I have had great success with one LS ignition
and one magneto.
Electronic ignition for the top plugs and magneto for the bottom plugs.
Benefits are: easy starting, variable timing for maximum efficiency and
no moving parts.
scsmith
Well Known Member
EI on the left
One of the advantages of the electronic ignition is the strong spark for starting, so I put mine on the left, in place of an impulse-coupled magneto.
And yes, it fires the top plugs.
The one small down-side risk is kick-back. If you have too low a voltage from a low battery and the starter doesn't quite get it cranking, the ignition may also loose its retarded spark feature and fire early. This (at least this is my understanding of the phenomenon -- others may correct me) can cause kick-back that can damage the starter.
So, just don't let the battery get so low
One of the advantages of the electronic ignition is the strong spark for starting, so I put mine on the left, in place of an impulse-coupled magneto.
And yes, it fires the top plugs.
The one small down-side risk is kick-back. If you have too low a voltage from a low battery and the starter doesn't quite get it cranking, the ignition may also loose its retarded spark feature and fire early. This (at least this is my understanding of the phenomenon -- others may correct me) can cause kick-back that can damage the starter.
So, just don't let the battery get so low
Whatchit!
Steve if you removed the impulse mag, you need to make sure you can't or don't ever start on the non impulse mag. You'll bust a starter or ring gear almost guaranteed.
I believe most leave the impulse mag and remove the non impulse so if needed you can still start on the mag or just use both without concern.
Tim
Steve if you removed the impulse mag, you need to make sure you can't or don't ever start on the non impulse mag. You'll bust a starter or ring gear almost guaranteed.
I believe most leave the impulse mag and remove the non impulse so if needed you can still start on the mag or just use both without concern.
Tim
Why Mix Ignitions?
The life-cycle cost of mags exceeds the initial higher cost of an EI: inspections, parts, expensive plugs and harness. Why are you retaining one mag? If it's fear that EI's are failure prone, why are you installing even one? Mags fail, too.
Then, you have increased your parts count, inventory needs, and skill set to service two ignitions types. Since the mag doesn't contribute much to the engine's operation with the EI lighting the fire sooner and hotter, why keep it?
John Siebold
The life-cycle cost of mags exceeds the initial higher cost of an EI: inspections, parts, expensive plugs and harness. Why are you retaining one mag? If it's fear that EI's are failure prone, why are you installing even one? Mags fail, too.
Then, you have increased your parts count, inventory needs, and skill set to service two ignitions types. Since the mag doesn't contribute much to the engine's operation with the EI lighting the fire sooner and hotter, why keep it?
John Siebold
RVbySDI
Well Known Member
Old ways die hard. Old men hang on to old ways. Old men convince young men that old ways are better. Young men take up old man's ways. Young men become old men. New old men hang on to old ways. Old ways live on!
Old ways die hard. Old men hang on to old ways. Old men convince young men that old ways are better. Young men take up old man's ways. Young men become old men. New old men hang on to old ways. Old ways live on!
That's largely true, we see it time and again. I'm in the same boat with ignition choice and I'll put in one impulse mag and one EI - but I'll tell you why and it has nothing to do with gray hair. I've modified my fuel system to eliminate the engine-driven pump and go with dual electrics pulling cool fuel directly from the wing (as a few others have done) and pushing forward under pressure to eliminate vapor lock issues on our tightly-cowled engines. That makes my airplane electron-dependent for continued flight - which means I have to take that into account. All my panel EFIS have internal backup batteries good for at least an hour, I will have a backup alternator, and an emergency bus that can shed almost all load if needed to keep the fuel pumps turning as long as possible if for some reason both alternators go Tango-Uniform. If I can shut off the EI and keep going on the mag, that's more load shed available to me in an emergency, and that's worth having it for me.
walkman
Well Known Member
Old ways die hard. Old men hang on to old ways. Old men convince young men that old ways are better. Young men take up old man's ways. Young men become old men. New old men hang on to old ways. Old ways live on!
Yeah, we'll, maybe. But there are other considerations, particularly if you are modifying and already flying airplane rather than building.
In my case the single most important factor is safety/redundancy. Removing a bendix d3000 dual mag that has many failure modes than can take out both ignitions with an electronic version that also has failure modes that can take out both ignitions is fruitless. So, that implies dual circuits, dual batteries, additional annunciation etc etc. doing only one side is a significantly easy install to achieve the same goal.
