Pistons ("Priora"): types, choice, reviews

It is possible to repair the engine after breaking the timing belt, but you will have to spend on this mass of effort, money and time. Therefore, many car owners do not wait for the belt to break, and the pistons will meet with the valves, and immediately install other, protected pistons. "Priora" with similar details works the same as with factory ones. But the risk of breakage due to the breakage of the timing belt is reduced to almost zero.

Now there are several manufacturers that produce spare parts for this engine, including pistons. "Priora" is completed with products from Russian companies "STK", "STI" and "Avtramat" from the Ukrainian manufacturer. Let's see what these products represent.

general information

The piston in the internal combustion engine is designed to transfer the rotational energy to the crankshaft. This energy is produced by combustion of the mixture. When the mixture of air and gasoline explodes, the gases expand. The latter presses the parts on the surface and pushes it. During operation, the piston surface experiences high thermal loads. Pressure in the motors "Priora" can reach a mark of 65-80 bar.

During operation, the Priora pistons are accelerated to a speed of 100 km / h with some periodicity and then decelerated to zero, while the operating frequency at 6000 rpm is 200 Hz. When the fuel-air mixture burns, the heating in the chambers can reach 1800-2660 degrees. This is several times higher than the temperature at which the metal melts. As a consequence, the strength of the alloy decreases. In the body of the piston, various stresses arise because of sudden temperature jumps, and besides, a voltage is added from pressure and inertia during accelerating-slowing processes at high frequencies.

Device

In order for the crank-connecting rod to serve in such difficult conditions, the part must be light and resistant to wear. The alloy has a high thermal conductivity - due to this, a rapid cooling on heating is ensured.

The outer surface is formed in such a way that there is never a risk of jamming the part inside the combustion chamber. Gases should not enter the crankcase of the engine. In view of the temperature difference between the bottom of the piston and the skirt, the element is made in a barrel-like shape. Therefore, it meets all the requirements.

To compensate for the deformation of the skirt during operation, the mechanism is made with a so-called "anti-ellipse". The major axis of the part is perpendicular to the hole for the finger. The top part of the piston is the so-called head. It has a bottom and special grooves. They are fitted with O-rings. The piston head can withstand high loads, it has a special protective coating.

The grooves for the piston rings are made at a slight angle. This ensures that the outer edges of the rings are positioned higher than the inner ones. The manufacturer prevents the formation of the slope of the groove cross-section down under high-temperature conditions. This is not the last characteristic that distinguishes pistons. "Priora" is equipped with such elements that "slide" in the combustion chamber. To do this, their working surface is covered with special compounds. To make the part better worked, coatings are applied which will eventually wear out during the running-in process. Often this is a phosphated tin compound. This coating also reduces the occurrence of scratches during cold start. Antifriction materials remain on the piston for good. They prevent cracking of the working part of the part and erosion.

The skirt of the piston is processed by special incisors in production to create a microrelief. So oil is better retained on the surface, thereby reducing friction on the pistons. "Priora" will withstand heavy loads on the KSM. All these parameters are identical to the pistons of third-party manufacturers. The products of STK are very weighty - they mention reviews. They are heavier than all other models.

Reasons for replacement

Here everything is very individual. Car enthusiasts say that if you fully comply with all the maintenance regulations, install parts from the original manufacturer or simply quality analogues on the Lada Priora car, then the engine will never let you down. Everything will work in normal mode. But everyone wants to save on spare parts or do tuning "Priora". Here there are questions. For example, if you save on the gas distribution mechanism, installing poor-quality rollers and a belt, the replacement interval decreases slightly. For example, the timing belt is normally set to change every 50 thousand km. On non-original spare parts you can travel up to 10 thousand km.

Pistons "STI"

STI is a Togliatti company. Pistons are manufactured using hot pressing technology. If you analyze the reviews of all those who have already bought parts of this brand for the Lada Priora car, you can see that they greatly reduce the efficiency of the engine. This can be explained by the fact that compared to the products of "STK" and "Avtramat", the details of "STI" have a lower compression ratio. The combustion chamber has a large area due to too deep samples for the valves.

The composition of the alloy reduces the content of silicon. This affects the strength characteristics of the part at high thermal loads. A reduced amount of nickel makes the part resource below. With these disadvantages, these pistons have a high price. But while forged products from the company "STI" significantly lose the rest of the brand. Pistons "Avtramat" ("Priora" they are also manned), these shortcomings are deprived, as well as "STK". However, there have been cases of belt breaks on cars with these mechanisms.

"Avtramat"

These are details of Ukrainian production. Pistons are made at the Kharkov enterprise. The part is produced by casting. The alloy completely repeats the one that the original spare parts. Also, the factory dimensions of the VAZ pistons are repeated. But unlike the original, the Ukrainian element has deeper samples. This gives him a lot of advantages over the regular part, if the timing belt breaks. As for the compression ratio, it remained unchanged. Therefore, if you install these products, the power characteristics of the engine, the difference will not be noticeable.

Due to the fact that the samples are enlarged, the area of the combustion chamber has grown a little, the efficiency should be lower relative to the regular spare parts. However, the figures differ slightly. Thus, the figure is 53.2 cm ² for the original and 53.3 cm ² for the "Avtramat". In practice, this is completely invisible. There is another plus that these pistons have. "Priora" (the price of parts is 3 times less - 2 thousand rubles, than for products from "STI" - almost 7 thousand) in service will cost inexpensively if you use these products.

STK

These parts are produced on the basis of the enterprise in Samara. Their technical characteristics practically do not differ from the products of "Avtramat". The difference in the weight of the piston. Due to the higher weight, the acceleration dynamics of the car is reduced. Also, the pistons "STK" have a higher price.

Advantages of installing non-standard pistons

Elements with grooves for the valves are very hardy. Even if the timing belt is broken, the upper camshaft and the valve are simply locked in place. The piston will go down due to the crankshaft, and nothing terrible will happen. The valve will fail in the grooves created for them. Next, the owner will need to drive the car to the service station, where specialists will restore the timing mechanism. This is a huge plus.

It should be noted that if there are no such potholes on the pistons, serious repairs are expected as a result of the belt rupture of the owner. Under the replacement are directly pistons and valves, as well as the pastel of the camshaft. The cost of such repairs can start from 30 thousand rubles. Therefore it is necessary to install pistons "STK" or the like. Protochki will save from expensive repairs.

Minuses

If the piston is light (as far as possible), then the motor will add to the power. You can achieve an increase in dynamic performance by 5-7%. Pistons with lungs can not be called lungs. To make a recess in the top of the part, it is required to have a sufficiently thick wall. This makes it harder, because of what power is lost.

In addition, these grooves change the compression of the combustible mixture. This also affects the thrust of the powertrain. If we sum up, then with the installation of such a detail, the motor will lose the very 5% of its power. For the engine of 150 liters. from. This is 10.5 "horses". Another disadvantage is the higher fuel consumption. The dimensions of the VAZ pistons are the same as those of the factory ones, but due to the bores, the volume of the combustion chamber increases, even slightly. Finally, because of the increased volumes, the compression decreases. Detonation is also increasing.

Conclusion

With all the shortcomings, car owners still install non-standard pistons with grooves. This makes it possible to secure the motor in case of belt failure. In the opinion of motorists, the best pistons on Prioru are the products of Avtramat. They have an optimal price, weight and characteristics.