There are many different spark plug designs available in the market nowadays. Understanding the differences between them is beneficial in helping the engine to run properly and efficiently.

In the present study, a group of four spark plugs with different number of ground electrodes were chosen to explore their impact on the engine performance and especially the combustion instability.

The results showed that the amount of crossover of the ground strap, the dimensions of the ground strap and the gap width are the primary factors affecting the spark onset, flame initiation and kernel growth.

The plug that performed the best was a plug with no ground electrode where the amount of heat loses was the lowest and there was no obstacles affecting the flame growth. The coefficient of variation (COV) of this spark plug type was the lowest of the four main test spark plugs.