Its not complicated, but experimental
SvingenB said:
My experience with Lycomings are with old Cessna and Grumman that I rent. I have never given any thought that there are several different types of aftermarket ignition and fuel systems that can be bolted on. On this site I can read about e-mag, p-mag etc up to full FADEC, but I don't know what it all means (where does for instance CDI lie on the map?). Can someone here please give a short description of the different kinds of ignition and fuel systems that exist for the Lycoming?
Thanks
Well I don't do anything short.
To put this in perspective what is the "standard" for aircraft ignition and fuel systems. Magnetos are the standard ignition. They are points & capacitor and coil distributors that have their own dynamo. No electronics and self sufficient (power wise). Fuel delivery is either a simple updraft Crab or mechanical fuel injection. Again no electronics or fancy stuff and very simple and reliable.
Electronic ignition (EI) can in ideal conditions save 2% to 4% in fuel in cruise at lower power (less than 75%). There is some HP gain but that is not the main advantage of electronic ignition. The EI gets its gains in efficiency in part by making a hotter spark and ability to use variable timing to make timing ideal for power the engine is at. Power is determined indirectly through RPM and manifold sensors.
FADEC -Full authority Digital Control - I explain it more below, but it combines electronic ignition + electronic fuel control. The main advantage is more efficiency and less pilot workload. FADEC eliminates the manual mixture control. That function of leaning is totally controlled by the system. FADEC is basically very much like what ever modern car has, electronic ignition and electronic fuel control.
Most popular experimental EI's : E-Mag and Lightspeed
E-mag has two products E-mag and P-mag, same thing but one (P-mag) has a built in generator. As with any electronic ignition you need battery power. With the P-mag, once the engine starts the on board generator keep the spark going in case of total electrical system failure (alternator dies and battery dies); As you know regular mags are self powered. The E-mag (or P-mag) bolts right in where the magneto would normally go and is driven off the back of the engine. Advantage is hotter spark and the timing will advance when at lower power. Traditional magnetos are always at a fixed 25 degrees, which works OK but when flying at low power, such as at altitude above 8,000 feet, the fixed timing becomes less efficient.
http://www.emagair.com/Index.htm
Lightspeed Engineering. Has all the advantages of the above but a little different form, fit and function. The biggest diff is the "brain box" is separate and uses separate coils and trigger. The trigger is what attaches to the engine and tells the electronics when the spark. The "Plasma" ignition from Lightspeed can use either a crank trigger or "hall effect" trigger that bolts into the hole where the traditional mag goes, your option. The Plasma III is a true multi-spark CDI ignition, which is thought to be a little more high performance than the E/P-mag (which is an induction ignition). The "race" guys like the lightspeed. The Lightspeed ignitions also offer more options like RPM, manifold gauges and cockpit adjustable timing advance.
http://www.lsecorp.com/
Other players in the EI market:
Electroair: Been around a long time. Was one of the early units, before E/P-mag. They have been sold and updated. It's a cross between a E-mag and Lightspeed in some ways technology wise.
http://www.electroair.net/
Unison Laser: This is the only certified electronic ignition, called the "Laser" and made by Unison (Slick magneto manufacture). They look just like magnetos, because they are, magnetos with an electronic ignition piggy back. Again the advantage is improve fuel efficiency and gain a little hp, mostly economy and efficiency. They have had some rumor of problems like chronic high CHT's? Check the archives.
http://www.unisonindustries.com/ourproducts/lasarelectronicignition.html
Type of Ignition: CDI and Induction:
Most EI's use an "Induction Coil Ignition", basically a kettering ignition we've had for 100 years. A BIG FAT coil is charged and collapses. It works great, but as RPM increases the spark output goes down, because the time to charge the coil gets shorter. The only
CDI or "Capacitance Discharge Ignition" is the Lightspeed. Capacitors store the energy and the coil is really like a "step-up" transformer. CDI produce strong spark even at very high RPM's. Most choose a brand of EI in my opinion based on form, fit and function. The E/P-mag is compact, all-in-one unit, which is appealing to many. The Lightspeed has the CDI and separate components, which appeals to others, because the electronics can be located in a cool location. Also CDI's run on lower voltage, plus you have gauge and cockpit timing adjustment options offered. The P-mag is the only one with a self powered option.
FADEC - Electronic Ignition + Fuel control - Main player'(s)
Aerosance - FADEC is kind of in a whole different ballpark. It is
not only electronic ignition it controls the fuel supply. Basically is what you have on any modern automobile, all electronic fuel and ignition. You no longer have a manual mixture control, it's taken care of by the brain box. With these systems they have more sensors: mass air, cht/egt, fuel flow and fuel press, some times on each cylinder. The FADEC is able to adjust each cylinder's fuel individually. Standard airplane fuel systems (Carb or mechanical Fuel Injection) the fuel is just thrown at the engine and hope it divides about equal to each cylinder. Usually is close, but not precision. The down side is cost and lots of "stuff", complexity. So FADEC is electronic ignition + electronic fuel control.
Aerosance is the leader in this department: http://www.fadec.com/index.asp (they make FADEC for experimental aircraft and certified planes). In general if this is what you want you should buy it brand new from the start. To retrofit it is very expensive. My advice is don't. However if you have more money the Gates and love technology, go for it.
Precision Airmotive makes a "partial" FADEC. It does not control individual cylinder fuel metering, it's kind of mechanical fuel injection with electronic mixture control + electronic ignition, all wrapped together with a back-up power supply system. I say partial because its not FULL Authority, since is really can "tune" each cylinders fuel actively. No doubt a simplifying cost saving measure.
http://www.precisionairmotive.com/ (experimental only)
Search the archives for any one or a few of these: EI, FADEC, P-mag, E-mag, Lightspeed, Plasma, Laser. Welcome to the group, Cheers George
PS: The next question or Bottom line
is it worth it? Well check the archives there is plenty of opinions and experience. Some keep it simple, purest that like the good old simple carb/magneto, which suits their needs fine. Nothing wrong with that. Some like to add one EI and are quite happy. Some like to add dual EI to get a little more advantage. Dual EI is slightly more efficient than a single EI. FADEC? Its pretty new. Van's Aircraft has a demo or plane or two with FADEC, flying for a few years. Personally I don't think its worth it. However if I had nothing but money to burn, I might go for it. It will save fuel in theory. However some think (including me) it opens you up to more possible failures? That is not a debate. More things more failures possible. There is some thing elegant about FTT - "Farm Tractor Technology".
