I've been reading and talking to guys for a long time on this subject, and have gotten 50 different opinions. I understand the pro's/con's of the different variations (emag, pmag, lightspeed, slick, etc) but I can't come to any conclusion on how to setup the ignition based on the options or real data. Dual Pmags, one Pmag one slick, or one Pmag one Lightspeed are the three combos I've come down to...
Thoughts?
No one answered you... and I will keep the status quo... It is 100% YOUR decision, pocket book, choice and preference. If as you say understand all the pro's/con's of the different variations, then you can decide, unless you want me or some one else to tell you. What do you want? Do you max performance, cost no object? dual LSIII's and a back up battery. Good enough easy to install, dual P-mags. Is money an issue? MAGNETOS! Spend less money and time wiring, especially if you already have mags that came with the engine.
WHY EVEN DO EI? Because it does lower fuel burn (more efficient) and increases power. There are not to many mods that lower fuel and increase speed! Drag reduction comes to mind as win-win mod. Carb to FI is a fuel saver but not much gain in HP. The gains of EI are not huge, so the cost of EI over mags will never really pay back... However ONE EI is the most bang for the buck. A second EI does help but marginally.
1) As much as some bad mouth mags, I never had issue with for many 1000's of hours in many planes, BUT if you buy a new engine with a set of slicks that is the easiest, cheapest way to go. They will work, be safe, reliable. The only time mags were terrible was when they got the bright idea to drive two mags from one drive, on odd ball Lycs engines. Bad idea to state the obvious. I recall looking at new Lyc clones and asked about leaving the mags off... they discount was small.... it would be better to keep them and sell them I think.
2) There are only three main electronic ignitions systems on the market PMAG (they don't make EMAGS any more I believe), Lightspeed and Electroair. The first two are most popular. None of them are cheap, and with the
PMAG price increase they are $1,375 with with wire harness.
The cheaper LS is the plasma II $1,120 complete, but its not going to have the umph of the top end Plasma III model with MSD (multi spark discharge). This over comes the one draw back of CDI (capacitive discharge) short duration. CDI is always HOT or HOTTEST, but MSD adds some fatness to it. So you are going to realize the full potential of the LS system by going with the LSIII which is $1,395, about the same as PMAG. The PMAG's "induction ignition" will drop in spark voltage at higher RPM, wherea CDI or MSD ignition will not drop. However at a 2500 RPM Lyc (even with the wasted spark) the PMAG should be OK. The LSII should still be better than PMAG in performance, but enough to make the difference? May be but depends on you. If you go LS consider the plasma III.
Electroair is $1,275 in the middle At least one EI (any brand) is your best bang for the bucks assuming you have one good magneto. However dual EI is going to cost at least $2240 to $2790. The cheapest is the Plasma II at $1,120. The light speed prices are with crank trigger (which is improved). LS with magneto hall effect unit is almost a $200 option. So you can easily get two Plasma III's with hall effect up to $3000! That is a lot of cash. For grins, two brand new slick mags outright are about ($1600) and harness ($375),
total two new mags and harness $1,975! So it's cheaper. However if you get a new engine from ECI or Superior, mag credit I recall is small. Keep them and sell them...
3) Zero, One or Two EI? Cafe did tests, compared two mags to one mag + one EI (early Jeff Rose Electroair) vs two EI. There was a noticeable improvement with one EI. The second EI was a slight but measurable gain. As was mentioned EI works better at lower power, because the MAP sensor will advanced the timing (on a very conservative schedule). Mags are 25 deg BTDC all the time which is worst case max power timing. Fixed mag timing works OK in an engine that runs operationally from ~2300-2700 rpm from 18" to 25" of map. It's a compromise and protects the engine from detonation. The EI can advance a lot more, but the EI does not do it until the map gets fairly low. The EI is STILL better at higher power power, with the retarded timing equal to the mag, simply because it's a hotter fatter spark. EI is always going to give a HOTTER spark, may be longer, be more efficient by burning more of the fuel in jug. There is no problem going with one mag, one EI. It may be easier and save adding a back up battery, diode, switches. Again one EI gets you 90% of the gain. (I pulled that number out the air for illustration).
Light speed is CD (capacitance discharge) ignition, as was mentioned, has lower battery drain, may be better if the alternator dies. The single spark is short duration but the multi spark version is longer, which cost a premium. The Lightspeed will give more performance with advanced (racing) features (advance degree display and control, rpm and map output*). The LS offers crank trigger firing option AND a hall effect unit for the mag hole, which cost more. (* I just noticed EMAG now offers a serial output if you want to play with the timing curve.)
The
E-mag is a induction coil system (aka old but reliable automotive coil ignition, electronically triggered). It's all in one self powered unit... so there you go, may be the best choice for ease of installation. Plugs into the mag hole. I think they came out with a new generation, however they stopped making E-mags I recall (could be wrong). They are all P-mags now just because that is what people wanted. They still use that cheap looking barrier strip for electrical connections. I would like it if they put a pig tail with a mil spec/aerospace connector on it. All the spark wires go back to the PMAG like a magneto or car distributor. The LS has coil packs, which is kind of a pain.
Electroair is kind of like E-mag (induction coil) but with out the ease of installation, kind of like LS with seperate parts. It is a little less expensive than the EMAG. I am sure it is fine... If you want something in between the EMAG and Plasma III this might be it.
There has been reports of problems, whining or genuine Oh @#$% with every one of them... fortunate few and far between. For the PMAG and LS with mag hole driven hall option you need to have or buy mag gears. They are not cheap new from Lyc ... but PMAG I think now manufactures clones of those gears .. Just consider that adds some cost.
Aviation plugs or auto plugs? It seems the automotive plugs are fine and may be better for high voltage ignitions. The spring contact of the aviation plugs can arc.
Safety is the #1 factor, price, then form fit function. They all promise to be safe if installed properly. I don't think you need to go nuts on electrical redundancy, but with out a standard magneto or the p-mag in the mix, it would be wise to have a parallel electrical power source to ignition's.... figure that adds about 5 lbs.
The choice is yours. You know the numbers.... If you have working mags now go with that. You can add one PMAG later or what every EI you want... That will give you most bangs for bucks.... any thing else will be more complicated, more expensive, and the gains will be smaller than going from zero to one EI.
Lightspeed on one side with a mag on the other. 
