Do you know what the calorific value of spark plug means? How to choose?

Source: Today's Headlines-Automobile Eastern Hemisphere

Spark plug, as the terminal component of engine ignition system, plays a vital role. During the operation of the engine, the driving voltage of 12V is boosted by 20,000 ~ 50,000 volts of the high-voltage package, which is transmitted to the spark plug to ignite the compressed mixture, and the mixture burns and expands to complete the power stroke. Without a spark plug, the mixture can't be ignited and the engine can't run.

Spark plugs are also one of consumables and need to be replaced regularly. When we replace the spark plug, many people only pay attention to the material or pole number of the spark plug, but few people care about the estimation of the calorific value of the spark plug. Many people know that when replacing the spark plug, the calorific value of the spark plug cannot be lower than the original calorific value, but they think that it is not a big problem to be higher than the original calorific value. In fact, this is also wrong. Let's discuss the calorific value of spark plugs together.

What is the calorific value of spark plug?

The calorific value of spark plug actually refers to an index of heating and heat dissipation ability, and the heat emitted by itself is called calorific value. The calorific value includes nine numbers: 1 ~ 9, where 1-3 is low calorific value, 4-6 is medium calorific value and 7-9 is high calorific value.

The calorific value of spark plug indicates the balance ability of heat absorption and heat dissipation of spark plug insulator skirt. The higher the calorific value, the stronger the balance between heat absorption and heat dissipation of the spark plug, the higher the speed at which the spark plug can export heat from the combustion chamber and the lower the working temperature of the spark plug. This kind of spark plug is called a cold spark plug. On the contrary, the lower the calorific value, the worse the balance between heat absorption and heat dissipation of spark plug, the lower the speed at which spark plug can export heat from combustion chamber and the higher the working temperature of spark plug. This kind of spark plug is called a hot spark plug.

For example, spark plugs with calorific values of 5, 6 and 7 are recommended for the original car. If 5 degrees is selected, if the vehicle runs at high speed for a long time, the temperature of the spark plug head may be too high, causing hot fire and knocking, which will seriously affect the use of the spark plug.

If you choose 7 degrees, and the vehicle often drives at a low speed, it is easy to have the problem of carbon deposition in the spark plug. Carbon is a conductive material, and serious carbon deposition will cause engine fire and jitter. The higher the value of the spark plug, the greater its own heat dissipation capacity. In fact, the cylinder itself does not generate so much heat, and the heat dissipation is stronger, so it will reduce the combustion efficiency of the oil-gas mixture and affect the engine power.

What about the calorific value of spark plugs?

The calorific value is expressed by numbers, and the number in the middle of the general model is calorific value, and the units of different manufacturers are different. The calorific value of different brands is different, and the calorific value of each brand will have its corresponding model, which is applicable. For example, the calorific value of LDHRIK 16 is 6, and that of LDHRIKL is 7.

For example: D8RC and D8TC:

D indicates that the thread specification is M 12X 1.25 and the screwing length is 19mm.

8 indicates that the spark plug has a high calorific value (1 ~ 3 is a low calorific value, and 4 ~ 6 is a medium calorific value? Heat value, 7 ~ 9 is high heat value, the higher the heat value, the faster the heat dissipation, which is a cold spark plug. ,? The lower the calorific value, the slower the heat dissipation.

RC stands for resistance type nickel-copper composite electrode spark plug.

TC stands for insulator protruding spark plug.

Engines with high power and high compression ratio generally choose cold spark plugs with high calorific value; On the contrary, engines with low power and low compression ratio choose hot spark plugs with low calorific value. However, many engines now adopt new technologies such as turbocharging, direct injection in cylinder, variable valve timing and lift and even variable compression ratio, so the selection of spark plugs does not completely follow this law. General automobile engineers will finally determine the model and calorific value of spark plugs through strict calculation and experiments, so we should not easily change the model of spark plugs in use.

This article comes from car home, the author of the car manufacturer, and does not represent car home's position.