In order for the fuel (air-fuel mixture) to burn completely, it is necessary to correctly ignite it in the working chamber of the internal combustion engine (ICE). And for this you need a special element (which is the spark plug), which is relevant mainly for gasoline power units. Diesel engines also have their own devices, but they are made a little differently, so they will not be considered in this article. And we will begin the analysis with what types of spark plugs the modern automotive market can offer us. We also touch on the differences between them and along the way get acquainted with the features of choice.
General information
Spark plugs are an integral part of any engine. Their main role is to ignite the fuel in the combustion chamber using a spark created by an electric discharge. But it is worth noting that its power is not so small - about several tens of thousands of volts. Moreover, the operation of the engine, as well as its life resource, depends on the performance of this element.
If in fact, the car candle is a high voltage conductor. Unfortunately, not all drivers appreciate such important details. But their condition largely affects changes in the operation of the power unit. And to everything else, whatever the appearance of the spark plugs, they are directly related to changes in fuel consumption.
Candle loads
During the operation of the internal combustion engine, the spark plugs are subjected to a variety of loads:
- thermal;
- mechanical;
- chemical;
- electric.
With regard to thermal load, the following can be said. The spark plug is installed in such a way that its working part is located directly in the combustion chamber, while the contact part is in the engine compartment. The temperature here varies from a few tens of degrees at the inlet to 3000 ° C during the combustion process. Under the hood, this figure reaches 150 ° C.
As a result, due to such uneven heating in relation to the entire length of the part (the difference can reach several hundred degrees), thermal stresses and deformations occur. In addition, regardless of the types of automotive spark plugs, the insulator and metal parts have different coefficients of thermal expansion, which only aggravates the situation.
As for the load of a mechanical nature, it is worth considering the pressure difference. At the inlet, it is lower than atmospheric by 50 kgf / cm 2 , and when burning fuel, significantly higher. In addition, vibrations affect the spark plugs while the engine is running.
Chemical loads are caused by a variety of substances released during fuel combustion. Moreover, some of them can cause oxidative reactions in the most resistant materials. And this despite the fact that the working temperature of the electrodes and the insulator is about 900 degrees.
Not without the effect of electrical load. During the formation of a spark, which takes about 3 ms, a high voltage pulse acts on the insulator at this time. Sometimes it can go up to 20-25 kV, but some systems can produce much more voltage.
Types of spark plugs and their characteristics
After familiarizing yourself with the loads, it is worth moving on to discussing the technical characteristics of the spark plugs. If necessary, knowledge of this will help make the right choice. Actually, the parameters themselves:
- The heat number.
- The number of electrodes.
- Spark gap.
- Temperature Range.
- Life time.
- Thermal performance.
Consider each of these important parameters in more detail.
Something about the incandescent number
When choosing spark plugs, this is the very first thing experienced motorists pay attention to. This parameter indicates at what pressure the ignition will occur. By this is meant such ignition of the air-fuel mixture, which does not occur through the resulting spark, but from contact with a heated electrode.
Regarding any kind of spark plugs in a car, this characteristic is very important, and it must necessarily meet the requirements of ICE. Sometimes it is possible to use candles with an overestimated hot number for a short time. At the same time, products in which it is below the requirements are prohibited for use. Otherwise, this leads to undesirable consequences. This is the burning of pistons and valves, a breakdown of the cylinder head gasket.
Number of electrodes
A little over a century has passed since the invention of the first spark plug. And the first products had only one electrode. But progress does not stand still, and such necessary automotive paraphernalia is constantly being improved. Thanks to the efforts of some manufacturers, products with two, three, and even four electrodes began to enter the global automotive market, depending on the type of spark plugs.
Many vehicle owners mistakenly believe that the more there are, the higher engine performance. In fact, the goal of this step is slightly different - to ensure the quality and stability of sparking. In other words, if one fails, the work will continue through the other. In this case, interruptions do not occur. This stability in the engine can be clearly seen at low speeds. In addition, the use of several electrodes significantly increases the life of the spark plugs.
However, this is far from the only way. There are products on sale that have no side electrodes at all. In this case, auxiliary elements placed on the insulator come into play. This type of spark plug (photo can be found below) has good prospects. During the operation of the candle, several electrical discharges are formed alternately, and the spark seems to start dancing. Only such know-how has a high cost, on the basis of this, not every motorist can afford such a luxury.
Period of use
If the engine is in good condition, then, as a rule, the life of the spark plugs is 30 thousand km for the classic ignition system and 20 thousand km for the electronic one. At the same time, as many experts note, the actual value is two times higher. Only this can be achieved only in laboratory conditions. Only here you can create ideal conditions, which cannot be done during the operation of the vehicle in the usual mode. And often the appearance of spark plugs after work leaves much to be desired.
The importance of the spark gap
The spark gap of the spark plug is the distance from the central electrode to the side elements. Each manufacturer sets its own value, therefore, their thoughtless adjustment threatens with serious interruptions amid a decrease in performance.
If the electrode was accidentally bent, it is worth trying to return it to its original position. To do this, you can navigate to another product. In extreme cases, you can buy a new candle.
Temperature range of candles
The temperature regime of the spark plugs is also very important. It means heating their working part. Ideally, this range should be between 500-900 ° C, based on the operating mode of the power unit. Moreover, regardless of the conditions of the combustion chamber. Whether it is idle of the internal combustion engine or the maximum, the temperature of the spark plug must always be within the established norm. And this also applies to all types of spark plugs.
This state of affairs is due to the fact that carbon deposits form on the insulator due to the lowered temperature. This in turn causes interruptions in the operation of automotive candles. In addition, an increase or decrease in temperature negatively affects their service life.
Thermal parameter
This characteristic indicates the relationship between the working temperature of the spark plug and the internal combustion engine operating modes. In order to increase this parameter, the length of the thermal cone is increased, but there is a need to adhere to the established boundaries of 900 ° C. Otherwise, there is a glow ignition.
Based on this characteristic, candles are divided into two types (the heat value is indicated in brackets):
- Hot (11-14).
- Cold (twenty or more).
- Medium (17-19).
- Unified (11-20).
It is worth noting that all types of spark plugs work differently in the summer and winter. In this regard, it will be more rational to keep two sets on hand: in summer, use cold candles, and in winter, on the contrary, hot ones. However, it is still worth considering the peculiarity of driving. If you have to spend time in traffic jams quite often when driving in winter, then the best option is a hotter candle. At the same time, which Russian does not like fast driving, especially in the summer and outside the city? Then use colder items.
Overview of the types of spark plugs
Car spark plugs can be divided into different types, not only depending on technical specifications. Their material of manufacture should be taken into account. According to this, they can be:
Nickel candles are the simplest design. The central and side electrodes are made of nickel, therefore they have a low cost, and therefore they should be changed quite often. According to manufacturers, their resource is 15-50 thousand kilometers. However, our current realities are such that we can safely divide this value in half, and it turns out that the replacement frequency is once per year of operation.
Platinum candles are distinguished by the presence of soldering of the same metal on both electrodes (central and side). This significantly increases the service life to 50-60 thousand kilometers. This material is resistant to corrosion and holds well in high temperature conditions.
For iridium spark plugs, a mixture of two metals is used: an iridium soldering is deposited on the central electrode, and on the side elements - platinum. As a result of this tandem, the life of the spark plugs is further extended. According to manufacturers, it can be up to 60-100 thousand kilometers.
Talk about troubles
Over the entire life of the spark plugs, over time, carbon deposits form on them over time. Moreover, it can be of a different kind, which kind of acts as a good means of diagnosing the engine.
What is the difference between types of soot on spark plugs from each other? Each breakdown is characterized by its own shade:
- Oily - indicates wear on the valve stem seals and piston rings, valve guides.
- Black (dry) - indicates a malfunctioning candle. Perhaps due to lack of energy to obtain a spark of the required power. This is also a sign of low compression of the cylinders, poor carburetor operation, with regard to injection engines this is an occasion to check the fuel pressure regulator. Clogged air filter.
- Red is certainly not the kind of working spark plug. This usually happens when using different additives to oil or fuel. If there is a need for their frequent use, it is worth lowering the concentration, otherwise the carbon deposit will gradually increase. And this threatens unstable operation of the engine, since the patency of the spark will be noticeably worsened. Therefore, when it first appears, it is necessary to immediately get rid of it.
- White - indicates the absence of cooling candles, while the pistons are very hot. By and large, this is a sign of engine overheating.
- If the soot has a white shade of a weakly expressed nature and settles evenly, it is worth changing the fuel.
Features of the choice of spark plugs
To make the right choice of spark plugs, it is necessary to strictly follow the recommendations that are set out in the operating instructions for the vehicle or in its passport. First of all, it is worth paying attention to the incandescent number, the gap between the electrodes and the thermal parameter. This will allow you to enjoy the appearance of faulty spark plugs as little as possible.
Preferred should be trusted manufacturers, including:
These companies have already passed the test of time, and for a long time. Many drivers have already managed to verify the professionalism of these specialists, which is reflected in the high quality of their products.
It is also worth remembering the fakes that flooded any market, including the automotive one. So, for original NGK candles, the central electrode is perpendicular to the contact and absolutely flat.
BOSCH products have a brand mark just above the thread (belt). Also, there is no marking of the W8 ATS, which is usually put on fakes.
The contact output of the original DENSO candles does not shine, which is often found among fake products. The marking itself is clear, the surface of the frame is perfect, the electrodes themselves are centered.
Finally
We touched on the topic of carbon deposits on spark plugs; finally, we will try to analyze such an important question: which spark plugs are the best? It is very difficult to answer it unequivocally, since here it is necessary to be guided not only by acquired knowledge, but also by sound logic. For VAZ owners, buying candles at twenty or thirty dollars apiece would be a rash, stupid, and pointless decision. According to the same logical scheme, it is unlikely that any owner of expensive luxury in the person of Mercedes will buy cheap products that have a reduced resource and poor performance.