Owners of Lada Priora cars often get into unpleasant situations. Breakage of the timing belt leads to sad consequences. The thing is that the pistons that the manufacturer installs at the factory when assembling the engine have insufficient depth samples. The motorists call these samples tsekkov. This is the cause of destruction. Repair of the motor after such an accident will cost the car owner expensive. It’s cheaper to replace the regular ones with the so-called non-plug pistons with the Priora.
Physics of pistons, loads
This element is designed to convert energy from a fuel explosion into translational motion and transfer them to the crankshaft. When the gases expand after the explosion, mechanical and thermal effects are exerted on the piston and its working surface. The item is experiencing high intensity loads. The maximum possible pressure in the Priors engine can reach 65-80 bar. This is almost a few tons.
In the process, the pistons can periodically accelerate their movement to 100 km / h or more. Also, their movement can slow down to almost zero at a frequency of up to 200 Hz at 6000 rpm. When a mixture of fuel and air explodes in a cylinder, the temperature inside can reach 1800-2600 degrees. Under such thermal influences, the strength characteristics are reduced. Thermal stresses occur due to sudden temperature changes. It is also worth adding stresses from the pressure of combustion products and inertia during accelerations and decelerations at high frequencies.
About the design of standard pistons
In order to work in such conditions, the part should be as light as possible. And the material is resistant to wear. Also, the alloy must be characterized by high thermal conductivity. This will ensure a high cooling rate. External work surfaces must be made so that the part does not jam in the heated cylinder. Also, the combustion products must not penetrate the crankcase. The piston has a barrel-shaped shape, there is a big difference between the degree of heating of its working part and the skirt. This allows you to satisfy all requirements.
To compensate for possible deformation of the skirt during operation, the piston is made with an “anti-ellipse”. The major axis of the part is strictly perpendicular to the axis of the pin hole.
The piston head or its upper part includes a bottom. There are also special grooves for mounting o-rings. So that the upper part can cope with high loads, at the production stage it is covered with a special layer of protective coating. The grooves for installing the rings are made so that there is a small angle. This ensures that the outer edge of the ring is higher than the inner. This allows you to prevent the slope of the cross section of the groove down during operation at high temperature loads. To ensure better sliding, the piston is treated with special coatings over the entire working surface. To make the part better run in, apply such coatings that wear out during the running-in process. This is a tin coating or phosphating. Slip improvers remain on the surface throughout their life.
The skirt is processed using cutters. This is done to obtain a microrelief. Due to this, the oil is better retained on the surface of the part, thereby reducing friction.
Differences in the design of “safe” pistons for the Priors
So, non-plug pistons on the Priora practically do not differ from the standard ones. This is actually an exact copy of the standard piston for engines from AvtoVAZ.
But on the top of the traditional mirror there is no - instead, there are deep samples. This allows you to protect the timing parts and the pistons themselves when meeting with the valves. Dimensions and all other parameters fully correspond to the characteristics of standard parts.
Why install non-factory pistons?
On each car it is individual. If you fully comply with the manufacturer’s engine maintenance regulations, install recommended or at least high-quality spare parts and consumables, then the car will serve for a long time and in good condition, and all mechanisms and components will work in their normal modes.
But everyone wants to save money or make car tuning, and a number of questions appear here. If you save on timing (and this is the belt and rollers to it), buying obviously low-quality parts, then it should be borne in mind that their replacement intervals will also fall as well as the price. For example, if on a standard AvtoVAZ engine the belt should be changed after 30-50 thousand km, then on cheap and non-original components rarely anyone could drive more than 5-10 thousand km.
Some tuning experts are trying to take everything from the engine and even more than what it can give. Motors are often equipped with compressors. However, most of the parts and components in the engine are not designed for such loads at all. The engine can not work long in the ranges of 7-9 thousand revolutions. The timing mechanism is also not designed for such operation - the weakest link is always damaged. And this is a belt. And what to do when you want to save money and not drive slowly? You can get out of this situation by installing non-plug pistons on the Priora.
Advantages of installing safe mechanisms
Even inexperienced motorists know that a system with non-plug pistons will be more secure and tough. Even if the belt breaks, the upper camshaft will simply stop. The piston moves from below due to the impact of the crankshaft. If non-plug pistons are installed on the Priora, disaster will not happen. Valves will enter the grooves and will not bend. Even if the belt is torn, the car can be transported to the service station. This is a great advantage.
disadvantages
In the process of creating various AvtoVAZ engines for front-wheel drive models, designers and engineers initially created similar pistons. Prior had non-plug grooves already from the factory (in earlier versions). More often they can be found on VAZ engines of the tenth family. This was due to the use of a belt instead of a chain. If the piston is lightened as much as possible, then the motor acquires an additional 5-7 percent of power, which is a lot. Replacing the pistons on the Priore with non-plug power will not add. This will only protect against expensive repairs. To make a groove, it is necessary that the surface is thick enough. The piston is made heavy, which takes power. Groove also unsatisfactorily affects the compression of the combustible mixture. This also affects power. As a result, if you install such parts on a car, then the motor loses 5-7% of its power. For an engine of 150 liters. from. it's 10.5 liters. with, which is very significant.
This is what those who have already installed non-plug pistons on their Priora car write. Reviews show that, in addition to reducing power, fuel consumption has increased. Detonation increases due to uneven weight distribution.
Piston manufacturers for Priors
So, the car owner decided to protect himself and is thinking about installing protected pistons. Let's look at what non-plug pistons on the Priora are on sale, which are better to purchase and install.
STI, Tolyatti
These products are manufactured in Togliatti using hot pressing technology. Judging by the reviews of those who have already equipped them with the engine, the details significantly reduce the efficiency and engine power. This can be explained by a low compression ratio and a large cylinder size. Valve samples are too deep.
The low silicon content in the alloy does not affect the strength characteristics in the best way. Lower nickel content reduces resource. At the same time,
forged pistons from STI have a high cost.
STK
The Priora pistons are non-plug STK produced in Samara. The characteristics of these products are practically no different from regular pistons. The samples are quite deep. Owners may not worry about the consequences of a timing belt break. Of the shortcomings, a higher mass can be distinguished. This affects the dynamics of acceleration. But adequate cost is a decisive factor when choosing.
Conclusion
Thus, it is clear that safe pistons have many advantages. These advantages are undeniable. Each owner of cars of this model must install non-plug pistons on the Priora. Which to choose depends on the goals and objectives. If you need reliable and inexpensive, then this is STK or Ukrainian Avtramat. However, the plant in Kharkov stopped production, and all stocks were almost sold. And STI is not worth its money, reviews say.