Characteristics of spark plugs

The standard for spark plugs usually uses calorific value to characterize the thermal characteristics of spark plugs. The calorific value of spark plugs represents the balance ability of the insulation skirt of the spark plug to absorb heat and dissipate heat, with a higher calorific value. The stronger the balance between heat absorption and dissipation, the lower the calorific value of hot type spark plugs and the higher the calorific value of cold type spark plugs. Generally, engines with high power and high compression ratio use cold type spark plugs with high calorific value; On the contrary, engines with low power and low compression ratio choose thermal spark plugs with low calorific value. The selection of spark plugs is generally determined by the factory through product design experiments and should not be replaced arbitrarily
Choosing a spark plug can determine its calorific value based on the engine's compression ratio, speed, and air fuel ratio.
The calorific value of commercially available spark plugs ranges from 5 to 13. The larger the value, the colder the spark plug, which is known as a cold type. High compression ratio engines require the use of cold type spark plugs. The smaller the value, the hotter the spark plug, which is a hot type. Low compression ratio engines use hot type spark plugs.
The production of colder spark plugs is more sophisticated than ordinary products, so it can ensure the accuracy and quality of ignition during high engine RPM, thereby ensuring maximum power at the limit of the engine. In addition, its resistance is also controlled very small, and the number of trips is not lost due to the increase in speed. So using spark plugs with higher values is greatly beneficial for habitually increasing engine speed.