ELECTROAIR IGNITION SYSTEMS

On a traditional dual magneto system, both magnetos are timed to fire at 25 degrees before Top Dead Center (TDC). When starting the engine, the ignition switch grounds the ‘P’ lead to the right magneto, stopping it from firing. Meanwhile, the left magneto with the impulse coupling can still fire. The impulse coupling causes the magneto to fire at TDC, and will continue to fire at TDC until the engine reaches about 200 RPM. At this time, the impulse coupling disengages and the magneto falls back to firing at 25 degrees before TDC. Once the ignition switch is released from the start position, the right magneto also begins to fire. From now on, no matter what the RPM, power setting, or altitude the engine spark timing will remain at 25 degrees before TDC. At any altitudes, a cylinder on the intake stroke draws in fuel and air. At lower altitudes, on the compression stroke (as the piston moves up) at 25 degrees before the piston reaches the top of the cylinder (TDC), the spark plug fires lighting the air/fuel mixture. The objective is to reach the peak pressure point (as a result of igniting the air/fuel mixture) by the time the piston reaches 11 degrees past TDC. As altitude increases, thinner air reduces the oxygen available for the proper fuel-air mixture creating more space between the air/fuel molecules. When the spark plug fires at 25 degrees before TDC, the thinner air/fuel mixture will burn slower. Therefore, the peak pressure point occurs much later than 11 degrees past TDC, and hence there is a loss in power. By advancing the timing based on RPM and atmospherics, the peak pressure point can be maintained much closer to 11 degrees after TDC. This can only be done with an electronic ignition system and is best done with an Electroair Ignition System (EIS)!   EIS Overview & Primer Before discussing the detailed mechanics of how the EIS works, we should overview the benefits and general operation of the EIS. The EIS differs from standard magneto systems in one very significant way: TIMING. In a magneto, timing is permanently set; the EIS adjusts timing (or spark advance) based on RPM and manifold pressure. This ability to adjust the spark advance allows the EIS to determine the optimum timing setting which produces the most power with the least fuel. EIS Spark Advance (Timing) = Mechanical Advance + RPM Advance + Vacuum Advance The mechanical advance is set during the installation of the EIS timing housing or crankshaft sensor. This setting is usually zero degrees of TDC. As the engine is started, the unit is set to fire the spark plugs at TDC. After reaching 650 RPM, the EIS will advance the timing to 18 degrees and stay there until the engine reaches 1000RPM. After 1000RPM, the EIS will advance the timing just less than 1/2 of a degree for each additional 100 RPM. Refer to the following RPM Advance Curve Chart, fig. 1: While the timing is advanced for RPM, the manifold pressure is sensed and calculated in to the total spark advance. These two measurements are used together to determine the most efficient timing setting for the engine. Refer to the following Vacuum Advance Curve Chart, fig. 2: If the MAP Sensor (manifold absolute pressure or vacuum) option is not installed, then the vacuum advance value in the above equation would be zero. Without the MAP sensor installed, the advance remains zero up to the 650 RPM. At 650 RPM, it immediately advances to the initial RPM advance setting. The advance then remains at the initial RPM advance setting until 1000 RPM, where it then advances in a straight line to the maximum RPM advance setting. If the MAP sensor is used, the advance will be the same as just described plus an additional 0 to 15 degrees depending on the manifold pressure.   Replacement Parts Available PN EIS-1 KIT Price Buy 08-05953 4-cylinder Electronic Ignition System comes with: Coil Pack, Controller, Mag Timing Housing, MAP Sensor, spark plug wires, instruction manual. Specify engine make and model. $1235.00 PN EIS-2 KIT Price Buy 08-05954 6-cylinder Electronic Ignition System comes with: Coil Pack, Controller, Crankshaft Timing Wheel, MAP Sensor, spark plug wires, instruction manual. Specify engine make and model. $1385.00 PN EIS-3 KIT Price Buy 08-05955 Subaru EJ-22 4-cylinder Electronic Ignition System comes with: Coil Pack, Controller, Subaru Timing Wheel Kit ( replaces COG pulley & factory pick-up ), and instruction manual. $1050.00 PN EIS-4 KIT Price Buy 08-05956 Rotorway RW 152 4-cylinder Electronic Ignition System comes with: Coil Pack, Controller, Trigger Wheel Kit ( mounts on V-Belt Pulley ), spark plug wires, and instruction manual. $1095.00