The Effect of Ignition System Power on Fast Burn Engine Combustion

The effect of varying the average ignition power from about 2 megawatts to 15 watts is investigated with the breakdown, capacitive discharge, conventional inductive, and long duration ignition systems on a fast burn, bowl-in-piston, single cylinder engine. The plug variables are held constant while the ignition energy for the different systems varies from 30-90 mJ. Lean air /fuel comparisons are made at idle and light load conditions using premixed propane as the test fuel. The breakdown ignition system, which is a high power modification of the capacitive discharge (CD) system, produces a faster burning rate and improved ignitability versus the CD system. The breakdown, inductive, and long duration systems are found to have comparable idle results and are superior to the CD system. The breakdown system creates the fastest burn rate of all the single plug systems. A conventional dual plug system, however, is shown to have leaner capability than the breakdown system at low speed, light load, operation. The results suggest that charge quality has an important interaction with the ignition system.