1. If I choose the option of one mag/one EIS, the mag has a fix firing advance and the EIS has a variable firing advance: how can this set-up work properly?
An electronic ignition always fires at 25 degrees or earlier. Magnetos are set to fire at 25 degrees, period. So the spark is already going when the mag fires and hence has very little effect.
2. What is the typical duration of spark for the EIS? How is this a benefit?
The EIS holds the spark for twenty degrees duration of crank. A magneto has a spark-duration of approximately five degrees of crank. A CDI system has an even shorter spark-duration than a magneto. The longer spark keeps igniting the unburned fuel which is spinning like a tornado as it comes by the spark plug. As a result, this longer spark leads to better fuel efficiency and cleaner plugs.
3. What are some typical fuel consumption gains when an EIS is used?
Typically a 10-15% fuel reduction can be expected is when using one EIS. At higher altitudes, the fuel reduction improves even more, in some cases as much as 30%. Also, we have recorded typical gains of an additional five horsepower on 4-cylinder Lycoming engines at low altitudes. At higher altitudes, the horsepower gain increases even more. (High altitude refers to cruising altitudes of 10,000 feet or more).
4. What are the voltage requirements to start and run the EIS?
We have systems for either a 12V or 24V aircraft.
5. Where should the coils and controller mount?
The coils are designed to mount on the engine side of the fire wall. The controller is designed for the cabin side - cool side. The MAP sensor can be mounted with the controller.
6. Is a back-up battery required if I run two EIS units?
Yes, for dual electronic ignition, we require a dual battery system.
7. What spark plugs do you recommend? Do you recommend automotive spark plugs?
You may use either the aircraft or automotive spark plugs. There are several hundred airplanes running the EIS with automotive plugs. Additionally, you must verify that the heat range of an automotive plug is correct for your engine or you risk causing severe damage. We prefer, however, the aircraft plugs as they have been designed to work with aircraft engines and do not require any modifications for installation.
8. Can I re-use my aircraft spark plug harness with the EIS?
No, you can not use a copper wire, or solid core harness. You have to use a noise suppression (a.k.a. resistive) spark plug wire in order to prevent unwanted RF noise from damaging the controller. Electroair supplies the appropriate harness wire with attaching hardware to complete your installation.
9. How long will an EIS last? Is there an overhaul requirement?
There is no TBO on the ignition. We have some systems with over 3000 hours of flying time. We do recommend that the Mag Timing Housing (when installed) be inspected and bearings replaced if necessary at engine overhaul. Electroair can do this for a nominal charge.
10. How is the timing picked up by the controller?
We use a 60 tooth timing wheel, with a single magnetic pickup. The 60 tooth timing wheel provides a high resolution signal which feeds continuous RPM information to the controller and virtually eliminates timing error. For 4-cylinder Lycoming engines, the timing wheel is enclosed in our Mag Timing Housing and replaces the right-hand magneto; for 6-cylinder Lycoming engines and all other engines, we use a crank-shaft timing wheel with the pick-up mounted on a bracket.
11. How long does it take to install one of your units?
Depending on your skills, installation should take 8-14 hours
12. Which spark plugs should the EIS be put on? All the top plugs, all the bottom plugs, or some top and some bottom?
It makes no difference which spark plugs the EIS is connected to. Approximately 90% of current users have installed the EIS on the bottom plugs because the hotter spark tends to keep lead from fouling the spark plugs and becoming a problem. (Bottom plugs have a higher tendency to fail because of lead fouling).
13. Does your EIS work on other aircraft engines like the Subaru?
Yes, we have sold many of our systems for use on the Subaru engines used on aircraft as well Volkswagen, Jabriu and others. Let us know what engine you're using and we’ll let you know if our system has ever been installed on a similar engine. We also will let you know if there is anything out of the ordinary for installing an EIS.
14. Will the "waste" spark damage my engine?
No, the coil fires a plug on the compression stroke and a plug on the exhaust stroke. This spark fired on the exhaust is called a "waste" spark and has no effect at all on the engine.
15. How does your system compare with a CD Ignition (Capacitor Discharge or CDI)?
The Capacitor Discharge Ignition (or CDI) does not charge an ignition coil, rather it uses the 1:100 winding ratio of the coil as a transformer. Initially, the 12 volts of the electrical system is converted to 200-500 volts and stored in a capacitor. When the spark is required, the capacitor is discharged into the ignition coil instantly producing a spark with duration of only 0.1 to 0.3 milliseconds. For many applications this spark duration is not long enough to ensure that the air-fuel mixture ignites completely.
A multiple coil ignition system, like the Electroair EIS solves this problem by using an ignition coil for every pair of companion cylinders. The time available to charge an ignition coil goes up. This allows the full benefit of an inductive charging method to be realized: the coil
16. Is there an equivalent to the impulse delay on one or both mags?
At any RPM below 500 the EIS sets the timing to zero degrees for starting or low idle. As RPM increases, the controller automatically advances the timing to the optimum setting.
17. If my engine has a dual magneto, how do I adapt my engine to use the EIS?
We use a split ring collar on the crank shaft for the electronic ignition timing pick-up. You can keep the dual mag install with one side capped off, or there are some single magnetos that will adapt to the dual mag hole.