Waste Spark Ignition

The Waste Spark Theory of Ignition Systems is based on understanding basic electric circuits. Electricity always travels in a circuit. Electricity leaves the source, travels through conductors and a consumer and returns to the point of origin. The coil secondary winding is the source of spark for the spark plugs. The spark must return there in order for the circuit to be complete.

The plugs that fire simultaneously (1-4, and 2-3) are wired in series with the coil. Since the polarity of the coil windings is fixed, one spark plug fires in the forward direction, from the center to the outer electrode, the other plug always fires backwards or from the outer electrode to the center. The spark travels from the coil through the conductor to the spark plug, the energy remaining after the spark has jumped the gap, travels through the cylinder head, through the companion spark plug and back to the coil.

One of the spark plugs will be firing on exhaust and the other on compression. The cylinder firing on compression will consume 80-90% of the energy produced by the coil. The cylinder firing on exhaust will consume the balance.

On the MINI the secondary ignition for cylinders 1 and 4 are paired as are 2 and 3. Cylinders 3 and 4 fire in the conventional manner from the center electrode out to the outer electrode. Cylinders 1 and 2 fire from the outer electrode back to the center electrode.