Introduction About Spark Plugs

If the engine is the ‘heart’ of the car, then the spark plugs are the ‘heart’ of the engine, without the help of spark plugs, the engine cannot work very well.The differences in materials, processes and ignition modes of spark plugs will lead to different impacts on the overall work of the engine. In addition, the heat value, ignition frequency and lifespan of spark plugs are depending on different materials.

The structure of the spark plug

图片 3The spark plug looks like a small and simple thing, but its actual internal structure is very complex. It is made up of wiring nut, central electrode, grounding electrode, metal shell and ceramic insulator. The ground electrode of the spark plug is connected to the metal case and screwed to the engine cylinder block.The main role of ceramic insulator is to isolate the central electrode of the spark plug, and then transmit it to the central electrode by high-voltage coil through wiring nut. When the current passes, it will break through the medium between the central electrode and the ground electrode and generate sparks to achieve the purpose of igniting the mixed steam in the cylinder.

The heat range of spark plugs

图片 1The heat range of spark plugs can be understood as the heat dissipation, in general, the higher heat range means the better heat dissipation and the higher affordable temperature. Generally, the optimal combustion temperature in combustion chamber is in the range of 500-850℃. According to the cylinder temperature of the engine, you can select suitable spark plugs. If the spark plugs’ heat range of your vehicle is 7 and you replace them with 5, it may result in slow heat dissipation and the head of spark plugs being overheated, sintering or melting. In addition, poor heat dissipation may cause the mixer to ignite prematurely and engine knock.

For distinguishing heat range of spark plugs, we can look at the length of the spark plug core. In general, if the spark plug core is relatively long, it is a hot-type spark plug and heat dissipation capacity is general; Conversely, the spark plug core with shorter length is cold-type spark plug and its heat dissipation capacity is stronger. Of course, the heat range of spark plugs can be adjusted by changing the material of the electrode, but changing the length of core is more common. Because the shorter the spark plug, the shorter the heat dissipation path and the easier the heat transfer, the less likely it causes the central electrode overheated.

At present, the mark numbers of heat range for Bosch and NGK spark plugs are different. The smaller number in model represent the higher heat range for NGK spark plugs, but the bigger number in model represent the higher heat range for Bosch spark plugs. For example, NGK's BP5ES spark plugs have the same heat range as Bosch's FR8NP spark plugs. In addition, most family car uses spark plugs with medium heat range. Also, when the engine is modified and upgraded, the heat range should also be increased according to the increase in horsepower. Generally, for every 75-100 horsepower increase, the heat range should be rose by one level. Besides, for high pressure and large displacement vehicles, the cold-type spark plugs are commonly used to ensure the stability of the spark plugs because cold-type spark plugs dissipate heat faster than hot-type.

The gap of spark plugs

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The spark plug gap refers to the distance between the central electrode and the side electrode. It should be noted that small gap will lead to premature ignition and dead fire phenomenon. On the contrary, large gap will lead to more carbon stains, power declining and fuel consumption increasing. Therefore, when you are mounting non-original spark plugs, you should not only pay attention to the spark plug electrode type and heat range, but also pay attention to the spark plug gap. Usually the last letter (Bosch spark plugs) or number (NKG spark plug) of the spark plug models indicate how big the gap is. For example, NKG BCPR5EY-N-11 spark plugs and Bosch HR8II33X spark plugs have a gap of 1.1mm.

Spark plugs are a very important part of the engine. If they have not been changed for a long time, ignition problems will occur which may eventually lead to a strike.


Post time: Jul-16-2020