Spark plugs are one of the most important parts that ensure the operation of the engine. The quality of ignition of the fuel-air mixture depends on the condition of spark plugs, which means the efficiency of the internal combustion engine as a whole. We tell you how automobile spark plugs differ from each other and how not to make a mistake when choosing them.
How does a spark plug work
What are spark plugs in a car for? To ignite the mixture of gasoline and air in the cylinders. A large electric voltage is applied to the elements of the candle (electrodes) located close to each other – today it is 25-30 thousand volts. Because of it, a spark leaps in the gap between the electrodes (cathode and anode), igniting the fuel-air mixture in the cylinders when starting and running the engine. The principle of operation in the gasoline engine candles is simple, but in the design of this element there are many nuances that affect the parameters of the part. Perhaps the most important of them is the caliber number.
What is the caliber number
In the process of operation, automobile spark plugs get very hot, since they are in direct contact with the combustion chamber. But high temperatures on the surfaces of the electrodes cause unauthorized and untimely ignition of the fuel mixture. As a result – the engine begins to vibrate, fuel consumption increases, power decreases. This unfavorable process is called caliche ignition. And the candles have such a characteristic as caliber number. This value is determined by the time after which the plug in a laboratory experiment will reach a state that leads to caliber ignition. Simply put, the caliber number shows the ability of the plug to remove excess heat.
And this is one of the main parameters of plugs, by which they differ. There is no single standard, denoting the caliber number. Each manufacturer of plugs encrypts it in the marking in its own way. But on the Internet it is easy to find tables comparing the caliber numbers in the designations of plugs of different brands.
However, do not think that a low caliber number is always a good thing, and high – evil. After all, it is at high temperatures (at least 400 degrees Celsius) that combustion of deposits on the electrode surface takes place. That is, their self-cleaning, allowing the candle to function properly for a long time. Consequently, colder spark plugs are more prone to contamination during operation.
How spark plugs are organized
A spark plug consists of four basic elements: metal housing, ceramic insulator, center and side electrodes. There are two characteristic types of spark plugs: single-electrode and multi-electrode. The most common single-electrode design has a central and one side electrode, between which the spark is formed. Candles of this design are the most affordable, but do not have the greatest resource and may not allow you to reveal all the possibilities of the engine, especially if it is a turbocharged unit with high power potential and gas pressure in the combustion chamber.
The multi-electrode plug is characterized by the presence of two to four side electrodes. Due to the direction of the spark, this design provides the formation of a more even flame front (direction of combustion propagation through the engine cylinder), which has a positive effect on the smooth operation of the engine. This is especially noticeable at idle speeds. Also a plus in the multi-electrode design is that the spark “chooses” for its formation the most suitable (for example, the least contaminated at the moment) side electrode. That is, it always has the highest possible power. Thus, the technological features of multi-electrode plugs allow you to increase the engine output, as well as improve its environmental parameters. The minus is the cost of such candles, which will be higher than that of single-electrode candles.
Which candles are better
What factors determine the work of the candle? There are several of them, and one of the important ones is the material of the electrodes. Candles with copper and nickel electrodes are the most budget-friendly. They will save money, and this will be especially noticeable if the engine has six or more cylinders. On the other hand, and the resource of such plugs is relatively low: it is usually about 30 thousand kilometers. So there may be no real benefit.
Many modern engines need spark plugs whose electrodes contain platinum or iridium. These materials are much better able to tolerate thermal loads, which allows the use of thinner electrodes in the plugs than in the design with copper and nickel elements, and with them better spark formation.
Such candles are not cheap: their cost is 2-3 times higher than that of parts with copper electrodes. However, the difference in price can be justified by better fuel efficiency (it can reach 3-7 percent). And the main thing is that the resource of such plugs is higher: platinum – about 80-90 thousand kilometers, and iridium – up to 100 thousand kilometers.
How to choose the right spark plugs
It is necessary to buy plugs from the list specified in the car manual, so as not to disrupt the engine. The same will allow you not to make a mistake with other characteristics of plugs. These include the type of thread (as a rule, car plugs have a thread M14×1,25) and its length – short (12 mm), medium (19 mm) or extended (25 mm), as well as the size of the head under the key. Now the most common are 16 and 21 mm.
As for the design and materials, it is better to choose iridium or platinum plugs, if the budget allows. Especially when there is a powerful turbocharged engine under the hood. You can also pay attention to multi-electrode copper or nickel plugs.
For everyday use in the car spark plugs can be taken with an average caliber number from the range that automakers specify in the instructions to the car. If you prefer dynamic driving, you can install spark plugs with a higher caliber from the permissible caliber number. They may also be preferable in hot climates.
In order for the spark plug to work reliably, it must clean itself from fouling. Black deposits indicate a malfunction in the engine, e.g. increased oil consumption
When to change spark plugs
The plugs in your car should be changed in accordance with the scheduled maintenance schedule, which is usually specified in the owner’s manual. As a rule, the periodicity of plugs replacement corresponds to their average resource – no more than 30-50 thousand kilometers for copper or nickel plugs and 80-100 thousand kilometers for platinum or iridium plugs. It is better not to bring to complete failure of plugs – modern engines and especially catalytic converters work in such mode is harmful.
It is also recommended to check the condition of plugs at each scheduled maintenance (even if their replacement during it is not provided) or earlier, if their unimportant condition is signaled by changes in engine behavior:
- power loss;
- increased fuel consumption;
- starting problems;
- missing ignition (engine “trots”).
And remember that most often the life of plugs is adversely affected by low-quality fuel with a high content of harmful additives, primarily metal-containing additives. This leads to the formation of hard-to-remove reddish deposits on the electrodes and insulator, which have electrical conductivity. As a result, the deposits actually short-circuit the plug electrodes and the plug stops working.
Total conclusions
- The main elements of the candle in the car – the body, insulator, center and side (one or more) electrodes, between which a spark is formed.
- One of the main parameters of candles – caliber number. Candles are “hot” and “cold”, the optimal caliber number is determined by the design of the engine and its thermal mode.
- So you should choose candles from the list of recommended for your car.
- The design of plugs can be single-electrode and multi-electrode, the latter are considered more powerful and resourceful.
- Electrodes can be made of more budget copper and nickel or with the use of expensive platinum or iridium. The latter serve longer.
- The plugs should be replaced in accordance with the routine maintenance schedule, and more often if necessary.