What engine parameters affect the operating temperature of a spark plug?
Air/Fuel mixture: Rich mixtures reduce the tip temperature, causing fouling and poor drivability. Lean mixtures increase both tip temperature and combustion chamber pressure, resulting in pre-ignition. It is important to read the spark plugs frequently while tuning after engine modifications, the spark plugs will help you achieve an optimum air/fuel ratio. Compression ratio/forced induction: As effective compression ratio increases through engine modifications or forced induction, a colder plug using a narrower gap and higher ignition voltage is required. Ignition timing: Advancing the ignition timing by 10° increases the plug tip temperature by approx. 70°-100°C. Engine speed and load: Increases in firing-end temperature are proportional to engine speed and load. When consistanly traveling at high engine speeds or hauling, towing, or pushing loads – install a cooler plug. Weather: Temperature, humidity, and barometric pressure all affect air density and intake volume. Higher intake vo
