When an eight-cylinder engine is running at 3,000 rpm, its ignition coil must do remarkable things. If a single coil is used, its magnetic field must be able to build up and collapse 200 times in 1 second.

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This is because there are 4 strokes per cylinder (intake, compression, power, exhaust) and 8 cylinders firing in succession, resulting in 32 total firing events per revolution. At 3,000 rpm, the engine is firing 150 times per second, and since each firing event requires both a buildup and collapse of the ignition coil's magnetic field, the coil must be able to do this 300 times per second (or 200 times per second if we only consider one of the two required actions per event).

When an Eight-Cylinder Engine Is Running at 3,000 Rpm, Its