Greetings, I would like to get the Maule communities input on the pros, cons, and colorful opinions, of the current batch of certified STC'ed EIS magneto replacements now available. There are three companies selling certified EIS units that I am aware of. These companies have STC'ed systems for the 4 cylinders engines as well, but I am limiting this post's information to the IO 540 W1A5 because that is what I have. The newest of the certified and STC'ed Magneto to EIS kits is (1) the Lycoming EIS, for the IO 540 W1A5 # 66K6D3SN-03 $1,650. This system is a fixed timing (23 degree) Magneto replacement. It use's the standard Slick spark plug harness. One unit can be installed with just a logbook entry. It is also legal to replace both Magneto's with 2 of these units, but this requires the addition of a back up battery ( there is one available as a kit from a third party vender listed in the Lycoming installation manual). A 337 field approval is required for the air frame modification, (additional wiring and back up battery). I like that this EIS is OEM Lycoming and the price is reasonable. The problem that I have with this setup is the fixed timing, the same setup is sold as experimental with variable timing. Come on Lycoming, WTF? After installing one of these units, I could add another unit later. If this unit had variable timing, it would be my pick.
Kit (2,a) is the ElectroAir EIS, for the IO 540 W1A5 using a crank angle sensor # 61000-T5C $3,940. or Magneto style (2,b) # 61000-T5M $4,440. Both kits come with spark plug wires. This system does have variable timing, but the STC is limited to replacing only one Magneto. The problem that I have with this system is the high cost and one unit limitation. Kit (3) is the SureFly EIS, for the IO 540 W1A5 # SIML6 $1,695. The STC is limited to the replacement of one Magneto. This unit has variable timing. The price is reasonable, it offers variable timing. Downside, the STC does not allow for both mags to be replaced.
I have zero actual experience with any of these systems, the information provided here is pilfered from the manufacture's website's, so please take with a grain of salt. I can't understand why Lycoming did not certify there system as a variable advance timing, when the others were able to do so. Hopefully they can in the future. It would also be great if Surefly could get a modification of there STC allowing two EIS units (with a back up battery and wiring). I am leaning towards the SureFly. What are your thoughts?

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