NGK bougies

As technology advances, the efficiency of the spark plug has increased, resulting in higher combustion efficiencies. The design evolution has reduced the quenching effect on the flame kernel. The quenching effect is the heat absorption by the spark plug ground electrode and center electrode, which hinders the flame kernel efficiency. The NGK spark plug has seen many changes to its design over the last 75 years, with most occurring in the last 30 years.