An engine is called a boxer engine, the cylinders of which are located in a horizontal order relative to each other. A similar structure scheme has a name: a V-shaped engine with a 180-degree camber angle. FROM of English language the word "opposite" is translated - "located opposite". Consider the boxer engine - the pros and cons.
Features of the boxer motor
Despite the similarity with the V-engine, the boxer has nothing to do with it. The difference is that in the boxer, two adjacent pistons are located in the same plane relative to each other. In a V-shaped engine, the pistons, when moving at certain moments, occupy the position of the upper and lower "dead center". In the opposition, they simultaneously reach either the upper "dead center" or the lower one. This improvement of the V-shaped motor resulted from the location of the cylinders at a developed angle.
Another innovation was the location of gas distribution mechanisms in a vertical plane. All this freed the design of power units from imbalance and increased vibrations, and made driving a car as comfortable as possible. Now the vibrations from the engine are not transmitted to the body and do not shake the car.
Boxer engines always have an even number of cylinders. The most common are four- and six-cylinder engines.
The design features of the boxer-type power unit have significant advantages over other types of motors:
The center of gravity is shifted down;
economical fuel consumption;
low vibration level;
increased motor resource;
passive safety in frontal collision.
The center of gravity shifted down allows for better stability of the car and optimal handling during active maneuvers and 
sharp turns. During sharp turns, roll is significantly reduced. The location of the engine on the same axis with the transmission provides the best transmission power. The absence of balance shafts saves fuel consumption.
The engine runs smoothly. A low level of motor vibration is achieved due to the coordinated rotation of adjacent pistons. The location of the crankshaft on three bearings, instead of the usual five, is another advantage of the boxer engine. This significantly reduces the mass of the engine and its length.
The location of the pistons in a horizontal plane gives the system greater rigidity, which significantly reduces mechanical losses during the operation of the power unit.
Passive safety is ensured by the fact that in the event of a collision, the motor easily goes down under the car. As a result, there is a decrease in the intensity of the impact directed at the passenger compartment.
The increased diameter of the cylinders provides the engine with high revs, which makes it possible to create sports-type models on this base.
Another feature is the characteristic sound during operation of the boxer power unit: it is more pleasant to hear.
Disadvantages of a boxer engine.
The advantages of the boxer engine are obvious. The disadvantages are:
Labor-intensive repair;
increased consumption of engine oil.
To repair the engine, it is completely removed. However, this is not the problem. Replacement parts are very expensive, and assembling the engine causes a lot of headaches. If, when repairing an in-line motor, the driver can independently replace the candles, then this is impossible in the boxer. Any repairs must be carried out on special equipment, which is available only at the service station.
The history of the opposition
Initially, this type of power unit was used in the military industry, in particular, on domestic tanks. In the future, Ikarus and the Dnepr MT motorcycle drove on similar engines. At present, two firms are engaged in the installation of a boxer on their products - Porsche and Subaru.
The first developments appeared in the thirties of the last century, when engineers Volkswagen group began to improve the V-shaped and in-line engine. In the sixties, the idea was intercepted Japanese firm Subaru. In 2008, Subaru releases the first diesel-powered boxer. Distinctive features - a four-cylinder engine with a capacity of 2 liters. Power indicator - 150 l / s.
Video principle of the Subaru boxer engine
Despite the high cost of spare parts and maintenance in service stations, the pleasure of driving a car equipped with a “boxer” cannot be compared with anything. High stability, easy handling, car responsiveness to all driver actions speak for themselves.
What do we know about the boxer engine? The fact that the pistons in it move horizontally. What this engine is the face of Subaru vehicles. Perhaps everything. Let's find out a little more.
boxer engine is one of the layout schemes of the internal combustion engine, in which the pistons are at an angle of 180 ° and move in a horizontal plane towards and away from each other. In this case, two adjacent pistons are always in the same position, for example at top dead center.
The movement of the pistons in the engine is reminiscent of a boxer fight, so another name for a boxer engine is boxer(boxer). A design feature of the boxer engine is the installation of each piston with a connecting rod on a separate connecting rod journal of the crankshaft. The boxer engine always has an even number of cylinders (2, 4, 6, 8, 10, 12). The most common currently four- and six-cylinder "boxers".
The boxer engine is not to be confused with the 180° V-engine. With external similarity in such an engine, adjacent pistons with connecting rods are located on the same connecting rod journal. So when one piston reaches top dead center, the other is at bottom dead center.
The indisputable advantages of the boxer engine are a low center of gravity, minimal vibration during operation and a high level of safety in frontal collisions.
The center of gravity of the boxer engine is shifted down to achieve better stability and controllability of the car. The low-mounted engine is on the same axis as the transmission, which results in more efficient power transfer.
The boxer engine is almost completely devoid of vibrations (there is only a moment from the forces of inertia of the second order, which tends to turn the engine around a vertical axis). Mutually coordinated movement of neighboring pistons ensures smooth operation of the engine. The weight balance in the boxer engine allows the crankshaft to be mounted on three main bearings (instead of the usual five), which significantly reduces the length of the engine and its weight.
The boxer engine is more compliant passive safety. In a frontal collision, the engine goes down under the car and, thereby, saves the lives of passengers in the cabin. No less important advantage of the boxer engine for drivers is the characteristic sound of its operation, which differs from other internal combustion engines.
Unfortunately, the boxer engine is not without its drawbacks. The most serious, in our opinion, is the high labor intensity repair work related to the design of the engine. So, to perform individual repairs, it is required to remove the engine from the car. Some sources note that the horizontal movement of the piston leads to uneven wear cylinder liners and, as a result, increased consumption oils. In view of certain overall dimensions the boxer engine is installed on the car only longitudinally.
Currently, boxer engines are being developed and installed on their cars. Subaru and Porsche. Previously, the boxer engine could be seen on Alfa Romeo, Citroen, Chevrolet, Honda, Lancia, Toyota, Volkswagen and even Ferrari cars.
Subaru has been using boxer engines since 1963. These are four- and six-cylinder boxer. The history of four-cylinder engines from Subaru spans three generations: EA(1966-1994); series EJ (1989-1998, crankshaft on 5 main bearings, 1999-2010, crankshaft on three main bearings); series Facebook(since 2010). Six-cylinder Boxers went into production a little later - a series ER(1987-1991), series EG(1992-1997), series EZ(since 1999).
Absolute majority boxer motors These are gasoline engines with distributed fuel injection and an overhead gas distribution system. They have one (SOHC) or two (DOHC) camshafts that are driven from the crankshaft by a timing belt or chain. Despite the different number of camshafts in the engines, a four-valve gas exchange scheme is implemented. A number of engines are turbocharged.
The third-generation four-cylinder Boxer turned out to be simpler, more compact, economical and harmless. To reduce fuel consumption, reduce the toxicity of emissions, increase the amount of torque and expand its boundaries in new engines, a lot of progressive technical solutions have been used:
- increased compression ratio by increasing the piston stroke and reducing the volume of the combustion chamber;
- reduced weight of moving parts (connecting rod, piston, crankshaft) due to forging;
- on the camshafts x intake and exhaust valves used variable valve timing system (active valve control system AVCS);
- a new oil pump was used, which provides high quality lubrication and increases engine life;
- a cooling system with separate circuits for cooling the cylinder block and block head was used.
In 2008, Subaru first introduced diesel boxer engine. The four-cylinder engine, 2.0 liters, develops a power of 150 hp. It uses common rail injection, a turbocharging system with a variable geometry turbine.
A number of Porsche models (911, Boxster, Cayman) are equipped with six-cylinder boxer engines. At one time, 8 and 12-cylinder boxer engines were developed for use in auto racing.
from the book by V.N. Stepanov
Tuning of automobile engines: SPb., 2000. - 82 p.: ill.5. MODERNIZATION OF THE EXHAUST GAS SYSTEM
In a modern car, the exhaust gas (EG) system has several important functions:
- muffling noise during exhaust gas exhaust to a level not exceeding the established sanitary standards;
- reduction of the amount of toxic components in the exhaust gas to values not exceeding the maximum permissible concentrations.
Along with the performance of these functions, the exhaust system must provide:
- good cleaning and purging of the engine cylinders;
- minimal energy losses of the exhaust gas on the way from the exhaust valves to the blades of the turbine nozzle apparatus;
- operation of the turbine at minimum fluctuations in the exhaust gas flow.
In addition, the exhaust system must have a relatively simple design and be manufacturable. Fulfillment of these requirements makes it possible to obtain an acceptable fuel consumption, reduce the likelihood of turbine blade breakage, reduce the metal consumption of the exhaust system and facilitate its maintenance.
The main problem when trying to equip a car with an effective noise suppression system is the difficulty of placing the silencer sufficiently large sizes. Usually this problem is solved by installing several (up to three) series-connected mufflers with smaller dimensions on the car instead of one large one. An important requirement for the exhaust tract in this case is the presence of a minimum resistance to the movement of the exhaust gas and, as a result, a reduction in engine power losses.
To reduce the amount of toxic components in the exhaust gas in the exhaust tract modern cars installed catalytic converter. The peculiarity of the developed designs of catalytic converters is that the effective neutralization of the contained
in the exhaust gas of toxic components, they are carried out only at the value of the excess air coefficient α = 0.994 ± 0.003. In order to determine the amount of oxygen contained in the exhaust gas and correct (if necessary) the composition of the air-fuel mixture to ensure efficient operation catalytic converter, a sensor is installed in the exhaust tract feedback, the so-called lambda probe, which is also called oxygen sensor. On some Toyota vehicles, such a sensor is installed both at the gas inlet to the catalytic converter and at the outlet of it. This allows the control unit to evaluate the efficiency of the catalytic converter.
It should be noted that when installing a catalytic converter, the resistance of the exhaust tract inevitably increases, which is accompanied by a slight decrease in the effective engine power (by 2–3 kW). So that the total resistance of the exhaust tract does not increase significantly when the catalytic converter is installed, the latter is usually placed in place of the pre-muffler. Since the maximum efficiency of the engine occurs when running on lean mixtures (≈α 1.05...1.15), forced operation of the engine in the entire range of loads on mixtures of almost stoichiometric composition inevitably leads to a decrease in efficiency (up to 5%).They strive to perform the exhaust tract of the system in such a way that, when carrying out the main functions assigned to it, it would contribute to a more complete cleaning of the combustion chambers from residual gases and a more complete filling of the engine cylinders with a fresh charge. Depending on the method of organizing the movement of the exhaust gas flow in the area from the exhaust valves to the inlet of the turbocharger turbine, the exhaust systems are divided into systems
constant pressure,
impulse,
pulse with pulse converters
ejection single-pipe.Exhaust systems of constant pressure due to the existing serious shortcomings on automotive engines almost no
apply.
The most widely used here are pulse and pulse systems with pulse converters. Let's take a closer look at these systems.
Due to the cyclicity of the working process in piston internal combustion engines in the exhaust tract, as well as in the intake, an oscillatory movement of gases occurs, as a result of which a pressure wave is formed.
Due to the large difference in gas pressure in the cylinder and the exhaust tract, at the first moment from the beginning of the opening of the exhaust valve, a significant amount of gases escapes the cylinder. During this period, called pre-release, a pressure wave propagating at the speed of sound is created. This wave, reflected from the walls of the exhaust pipeline, under certain circumstances, can prevent further outflow of gas from the cylinder, due to the large pressure difference in the initial period of release. The subsequent cleaning of the cylinder from residual gases is carried out in this case only due to the pushing action of the piston. Obviously, under such conditions, the amount of gases remaining in the combustion chamber from the previous cycle will be the largest. This will adversely affect the subsequent filling of the cylinder with a fresh charge and, accordingly, the power, efficiency and environmental performance of the engine.
However, the resulting pressure wave can also be used to create conditions behind the exhaust valve that improve the cleaning of the cylinder from residual gases. To do this, the exhaust system must be adjusted so that by the end of the exhaust process, during the existing valve overlap phase, a rarefaction is formed behind the exhaust valve during the passage of the wave. This will lead to an increase in the amount of residual gases flowing from the cylinder and an improvement in filling it with a fresh charge. The exhaust system is tuned by selection of the length and cross-sectional area of the exhaust pipelines. At the initial stage of work, the named parameters of the exhaust system can be preliminarily determined by the calculation method, but then it is necessary to verify and refine the results obtained on the test bench. When performing these rather laborious works, in order to reduce the number of experiments, in order to obtain the expected result, one should use the techniques known from the theory of experiment planning.
The practice of designing exhaust systems shows that the more cylinders one exhaust pipeline unites, the smaller the resulting pressure amplitude arising in the pipeline, which is formed as a result of the superposition of individual waves. Therefore, in order to avoid undesirable superposition of waves, the exhaust system is made in the form of several pipelines arranged in a fan (one above the other), each of which releases gases from no more than three cylinders. To prevent undesirable wave superposition, the gas flows from the cylinders are combined by pipelines in such a way as to ensure the alternation of gas outlets into each pipeline at the greatest possible intervals. At the same time, it is necessary to strive to ensure the same length of exhaust pipelines (in practice, this is not always possible to implement due to the existing overall restrictions). The implementation of these conditions is possible with a fan-shaped arrangement of the exhaust pipelines, when they are located one above the other. Ensuring the same length of pipelines allows you to adjust the exhaust system for a certain range of speed KV. In the impulse exhaust system, the exhaust gas is supplied to the turbine by separate pipelines from each group of cylinders.In an impulse exhaust system with an impulse converter, the pipelines that combine the exhaust from two or three cylinders pass into a Y-shaped pipe that performs impulse conversion, two paths of which are combined into one after a certain distance. Compared to classical pulse exhaust system pulse system with pulse converter loses by dimensional indicators, but allows you to increase the efficiency of the turbocharger and increase the resource of the turbine.
On the one hand, big, mighty V8 engines and V12s have their own appeal, there is something special about their sound. Plus power. But there is a bit of logic in small-volume racing engines, which at maximum speeds buzz like those power units.
For example, . The high-revving boxer engine, the EJ207, is loved by tuners and for good reason. For example, the Australian tuning company GotitRext decided to raise the boxer's performance to new heights.
The company took up tuning the boxer engine, supplying it with new internals and a Garrett GTW3884 turbine. Incredibly, with a 2.0-liter engine, it was possible to "remove" 610 hp in this way. off the wheels! However, this is not the most interesting.
The greatest achievement of the engineering team was the ability to implement very high speed. 12 thousand revolutions per minute! That's what an incredible "ceiling" rested against the performance of this engine.
It is not clear how GotitRext managed to bring the performance to such an unusually high level and not lose the reliability of the engine (the company claims that this is so). Due to the fact that not every transmission will withstand such levels of power and torque, the transmission has also been redone.