Impact of spark plug type on the cycle-to-cycle variability in an internal combustion gas engine

An experimental study was conducted using a single-cylinder gas engine to determine the impact of spark plug type on engine cycle-to-cycle repeatability. Two types of spark plugs were used for the analysis: the first was a flat electrode spark plug, and the second was a conventional spark plug with a side electrode, designated as “J”. The tests were carried out over an air excess ratio range of 1.0 to 1.4 and an ignition coil charging time range of 1.5 ms to 5 ms, at a constant engine speed of 1500 rpm and a load of 6 bar IMEP. The results indicate a significant improvement in engine repeatability when using a spark plug with a flat ground electrode. An average reduction of 61% in the IMEP variability coefficient was achieved in the air excess range of 1.0–1.3. The use of a spark plug with a side electrode “J” resulted in a reduction in the sensitivity of engine operation to changes in the mixture composition and coil charging time.