Effect of Leading and Trailing Spark Plugs on Combustion, Fuel Consumption and Exhaust Emission in a Wankel Engine

The aim of this study was to determine the ignition advance difference between the leading and trailing spark plugs found in the 13B-MSP (Multi Side Port) Wankel engine. The optimum ignition advance difference between the two-spark plugs had been determined by examining brake specific fuel consumption, emissions, p–V diagram, cumulative heat release rate and cyclical variations on the engine. Better results were obtained, if the advance difference was 15 or 20° in terms of total hydrocarbon and brake specific fuel consumption. It was observed that as the ignition advance difference decreased between the two-spark plugs, the combustion started earlier and completed in a short time, and when the ignition advance difference increased, the combustion started later and slower. Therefore, combustion improved with the ignition advance difference being 15°. The average of maximum pressures for 200 cycles was found as 20.48 bar, 26.11 bar and 17.36 bar in 5°, 15° and 30° ignition advance differences, respectively. 15° ignition advance difference was found to be faster to burn than other advance differences. It was observed that the optimum advance difference between the leading and trailing spark plugs should be 15°. Subsequently, single-spark plug (Trailing plug) and two-spark plug (Trailing + Leading plug) experiments were performed on different loads. As a result, two-spark plug compared to single-spark plug, fuel consumption and emissions decreased, and it was observed that combustion became better by increasing in-cylinder pressure and heat release rate.