Look Ma, No Mags!

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Ken Johnson replaced the magnetos on his Oshkosh Grand Champion Glasair III with a dual electronic ignition system from Klaus Savier’s Lightspeed Engineering. The following observations are excerpted from a letter Ken wrote to Klaus reporting his experience with the system. Ken asked that we share them with his fellow Glasair builders as well.

  • The engine starts easier whether hot or cold.

    Lightspeed Engineering Plasma II+ CDI with Direct Crank Sensor
  • No moving parts in this system. Mags are removed, holes are capped off, no mechanical drag. Redundancy is a second small battery charged by the main bus through a diode.
  • At lower altitudes I can see about a two- or three-knot increase in top speed. This almost surprises me as the engine “feels” stronger.
  • Climb performance is markedly improved. I didn’t try to measure this. You don’t have to. Your co-pilot will ask you what the heck you did to the engine.
  • The engine runs smoothly over a much broader fuel mixture range. For example, at higher altitudes the fuel mixture can be set at best economy, best power or full rich with only a four-knot variation in airspeed.
  • I’ve experienced no electrical/radio noise of any kind. I do have a Strikefinder, and it picks up the engine starter motor, the strobe lamps and the landing gear motor, but nothing else. The spark plug wires are unshielded automotive wires as supplied with the ignition system. The spark plugs are a smaller, fine-wire automotive type used with a bushing. I love these $5 plugs. I have over 100 hours on them so far, and it looks like they will have a long life span.
  • At higher altitudes (10,000 feet and above), the CDI units improve cruise speed by approximately ten knots, and the engine is very smooth.
  • CHTs are noticeably warmer.
  • Fuel burn, for me, is similar, but the speed is higher. Like you said, slow down to your original speed, and the fuel burn will be something like 10% less. Maybe someday I’ll try that!
  • Installing these CDI units is the cheapest way to increase power, smoothness and speed that I know of.
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