Spark plugs - how to choose the right one

Choosing spark plugs – what could be easier! I looked at the instructions for car and wrote down the required marking. However, it happens that the machine's operating manual is not at hand at the moment or you are offered several product options. In order not to make a mistake in choosing, it is worth knowing the structure and basic characteristics of these elements.

Design

In principle, it has remained unchanged for many years. There is a case inside which the main metal electrode passes, isolated from the side by ceramics. A high voltage is applied to the center pin of the spark plug from the ignition module (coil). As a result, a spark is formed in the air space of the cylinder, which ignites the fuel mixture. What should you look for when choosing candles?

Heat number

During continuous operation, this part is heated to high temperatures. As a result, it may turn out that the mixture will ignite not from a spark, but from a hot electrode. Those who drove a car with a carburetor engine probably remember the situation when the ignition is turned off, but the engine is still running. The situation is called pre-ignition. Many unpleasant surprises can be expected from him. Spontaneous ignition of the mixture is fraught with rapid wear of CPG parts, a decrease in the power of the power unit.



High temperature resistance shows the so-called. heat number. But there is an unexpected nuance here: each manufacturer spontaneously sets this parameter. And if for some brands an increase in the value indicates that the candles are becoming more “cold”, then for others the opposite is true. For example, at Denco, the “hottest” candle is indicated by the number “9”, and the most resistant to temperature is marked “35”. Bosch has the opposite: from "10" to "2".
The worse the part tolerates heat, the more resistant it is to soot. And if the candle is resistant to high temperatures, then more combustion products will settle on it. Therefore, a compromise is needed.

Side electrodes

One or several? For many, the answer to this question is considered important. There is a difference, of course, but not as big as it seems. Multi-electrode spark plugs began to be used when they began to use the ignition system, where the formation of a spark occurs 2 times more often than usual. As a result, the wear rate of the electrode increases. Therefore, they began to make an additional one: the spark always “chooses” the less worn one.



Today on sale you can find candles with three and even four electrodes. The completeness of fuel combustion and the power of the spark (engine) do not depend on their presence. But this increases the spark plug resource on some engines. If the car manufacturer recommends multi-electrode parts, then they should be installed.

Central electrode

The main characteristics of this part of the candle is the thickness. This parameter is especially important if a separate coil is provided for each of them (a similar system is used in the most modern motors). And here everything is simple: the thinner the electrode, the better the candle works: there is less carbon deposits and harmful emissions into the atmosphere, the spark is thicker, the fuel burns more completely.

A logical question arises: what is the best way to make a central electrode so that it is both strong, resistant to high temperature and durable? The most common answer is chrome-nickel alloy. The material is low cost. However, there is a significant minus - a large (2,5 mm) thickness. But you can’t do less: thermal erosion will “quickly” destroy the electrode. The solution was found.

Precious metal electrodes

When using rare earth elements, it is possible to make a candle that satisfies all of the above requirements. Electrodes made of platinum or iridium are five times thinner than nickel electrodes and they have the same operating life (an average of 100 thousand km, while budget candles “go” for 20 thousand kilometers). The cost of "precious" ignition elements is 4-5 times higher than the "classic" ones.

How to choose candles

Dimensions of a conventional product: 14 mm - diameter, 19 mm - length, 16 mm - nut size (it requires an appropriate key: usually on "21"). There are candles with a different geometry, but they are rare. Also, when buying, it is necessary to take into account the glow number recommended by the manufacturer, the gap, the number of electrodes. Therefore, the best option is to select the original product by OEM or manufacturers' catalogs.



However, disagreements may arise here: it is unclear who then to focus on? Ideally, the recommendations of car and candle manufacturers should match. But if this is not the case, preference should be given to those who make the details. Engineers of manufacturing companies are constantly improving products and it happens that improved candles have already appeared on the market, but auto manufacturers have not yet had time to order them.

But the main requirements should not be ignored. For example, if it is recommended to use only candles with an electrode made of iridium, platinum, parts with a nickel tip cannot be used. Otherwise, the sparking process will be disrupted, additional loads will appear in the system, fraught with breakdown of the ignition module and other electronics. Below are the brands that are popular with car owners.

DENSO 4702 IK20TT

In the manufacture of candles of this type, iridium is used. The Japanese manufacturer claims a service life of 120 thousand km. At the same time, reduced fuel consumption and a minimum of harmful emissions into the atmosphere are guaranteed. Some users note improved dynamics, a decrease in vibrations when idling. The negative points include the high cost.

Bosch SUPER 4 WR78

A product with four side electrodes and one central electrode is popular with motorists. The latter is covered with a layer of silver, which, according to the manufacturer, allows the product to self-clean from carbon deposits. The motor starts quickly even in severe frost. The declared resource is 50 thousand kilometers, which is due to the uniform wear of the part. Users note that there are many fakes on the market.

NGK 4339 DCPR8E

The product belongs to the budget segment. But it has characteristic features: a trivalent coating of metal parts that prevents corrosion processes. The insulator is made in the form of a body with corrugated recesses around the circumference, which improve heat transfer, which stabilizes sparking. The core is made of copper. According to users, the NGK 4339 DCPR8E model is a combination of acceptable quality and affordable price.

BRISK DR15YC-1

Also a popular brand. The main electrode is made of nickel alloy, the core is made of copper. Candles are suitable for cars that are constantly operated in the city. But on the track, the products also work effectively. The resource declared by the manufacturer is 30 thousand km.

When to change candles

This must be done in accordance with the manufacturer's recommendations. A candle with a nickel electrode rarely serves more than 20-25 thousand kilometers. It all depends on the level of load on the power unit, the operating conditions of the car, driving style. Even if the candles look “attractive”, with a pale brown coating, they still need to be changed: the gap between the electrodes increases, the insulator wears out. This increases the load on the ignition system and, as a result, threatens with a sudden breakdown of its elements.