Kettering ignition systems used on the majority of automotive engines can no longer assure reliable ignition for high-output engines. The capacitor discharge ignition, CDI, is a promising system to supersede the obsolete battery-coil. This study examines wave-front requirements at the spark plug for producing ignition in the internal combustion engine and system characteristics necessary for producing the wave-front. Arc requirements are described and used to define CDI parameters. A modified Kettering system which violates some basic ignition concepts was replaced by a CDI system designed in this study. Its characteristics were derived from arc requirements, not by aggrandizing the replaced battery-coil parameters. During performance tests, the CDI system exhibited superior performance. It fired simulated fouled plugs and continued to produce an arc when pressurized tx) 3 times the value at which the Kettering ceased to function. This improved performance was accomplished with approximately the same stored energy and less input power.

http://archive.org/details/ignitionsystemre00will

Lieutenant, United States Naval Reserve