Engineering C-D Ignition for Modern Engines

A new breakerless capacitor discharge ignition system has been developed by Delco-Remy Division, GMC. This unit provides important benefits to the vehicle operator, and has been designed to fit the requirements of modern gasoline engines. An extensive engine test program was conducted to establish the major design objectives. In this test program, it was found that under adverse cold starting conditions the system must produce 23-25 kv of ignition at the spark plug to insure reliable starts. Battery voltage may drop as low as 4.0 volts at this time.

It was also determined that an extremely rapid voltage rise at the spark plug is not necessarily best for smooth engine operation. A risetime of 35 microsec was chosen as a more nearly optimum choice to provide smooth engine operation and extended spark plug life. In the process of making applications for original equipment, a number of problems were encountered. Special provisions were found to be required for engine test instrumentation, and to reduce radio frequency interference to a satisfactory level. Benefits provided by this new system include the extension of spark plug life by as much as 4-5 times; improved cold starting; and the virtual elimination of traditional ignition distributor maintenance.