The device of the horizontally opposed Subaru engine
The pistons are at an angle of 180° and move horizontally towards each other. In this case, two adjacent pistons are always in the same position, for example at top dead center.
Subaru's engine was recently called the "boxer". The movement of the pistons is very reminiscent of a boxing match in the ring. A special design of the engine is that each piston (together with the connecting rod) is separately mounted on the connecting rod journal. crankshaft. The engine always has an even number of cylinders. That is, two, four, six, and so on. The most popular units are engines with four and six cylinders.
Many people think that this is a V-shaped motor with a camber angle of 180 degrees. Yes, outwardly there is a similarity: adjacent pistons with connecting rods are located on one connecting rod head. And if one piston is at top dead center, then, accordingly, the other is at the bottom.
Start of boxer engines
In the last century (1938), the first boxer engines were developed. Initially, they were installed only on auto volkswagen Käfer or Volkswagen Beetle. It was Volkswagen experts who invented the horizontal motor. Some of Volkswagen cars Group and in our time have such motors. In 1940, SUBARU mechanics began working on a new engine. Even now, Subaru installs boxer engines in their cars.
Pros of a Subaru engine
Here are some features of the boxer engine:
Low center of gravity. The feature has a positive effect on driving performance.
The location of the cylinders. Thanks to the good placement, the engine runs much quieter. The cylinders move towards each other in a horizontal plane, and there is almost no vibration. It extinguishes easily.
Great resource. The motor can run for a drive of 1 million kilometers. Of course, this is permissible if the engine is used correctly and consumables are changed in a timely manner.
Subaru engine cons
Boxer motors are very hardy to use. But still, there are downsides. Namely:
Repairing such a motor is very difficult.
The price of the motor is high. In most cases, the price depends on the complex structure;
Maintenance of such a motor is not easy.
While we discussed the pros and cons boxer motor, it is very powerful. Dynamic characteristics very similar characteristics gasoline engine. The similarity lies in durability and fuel consumption.
Reliable Subaru engines
There are 3 small displacement engines: EJ15, EJ16, EJ18.
Although they are not "millionaires", they are still durable. Suitable for C-class cars. The motor is not big, only 1.5 liters. There is no complexity in the structure. But he owns all the necessary details. There are 2 block heads.
One of the best engines- two-liter SOHC: EJ20E, EJ20J, EJ201, EJ202.
Although such motors are difficult to maintain, this is compensated by the strength that is in the normalized balance of motor resources. Owners of such engines can boast of their safety. It is no worse than in-line four-cylinder engines from Toyota with the same volume. This unit runs on 92-m gasoline. Fuel consumption is small. After a run of two hundred to two hundred and fifty thousand kilometers, you need to replace the rings.
Mid-level engines include aspirated DOHC (two liter): EJ20D; EJ204. These units are considered reliable. Their engine life is quite high.
Specificity Maintenance engine:
Difficult to replace spark plugs
The timing belt is replaced without errors;
Mechanical work - after removing the motor;
The engine runs on 95-m gasoline.
Engines Subaru Impreza wrx sti and Forester with turbines 
Although the fuel consumption is not high, the power units with the turbine work at 100%. But there is one drawback: with such work, the motor resource is rapidly exhausted. Some owners of cars with such an engine are satisfied with the regime: races, repairs, races again ... But if a person wants to use the car more often than repair it, then this is impossible with such an engine.
For example, the EJ20G and EJ205 engines are turbocharged. Their motor resource is limited to one hundred and fifty thousand kilometers. After that, it is not enough to make a standard motor repair. Most often, the engines are thrown away. After such a run, the connecting rod breaks, the pistons are destroyed and this indicates emergency wear.
But other turbo engines: 1) EJ20K; 2) EJ206; 3) EJ207; 4) EJ208.
Even 100,000 kilometers for such a motor is very good result. Often, cars with such an engine have only one owner. They are not purchased so that they rest in the garage. The owner of the car manages to "kill" him in a short time.
Subaru engine upgrades
It was the employees of Fuji Heavy Industries Ltd who made changes to the engine:
Improved dynamic performance;
Exhaust gases have become cleaner.
To achieve this, they increased the compression ratio in the middle of the cylinders. I also had to increase the piston stroke and reduce its volume. In turn, the volume of the combustion chamber also decreased.
The gas distribution system has been improved. Due to this, gas exchange has improved in the middle of the cylinders. The valves started working at the right moment. Strength has become much higher, and fuel consumption decreased significantly. More importantly, carbon dioxide exhaust pipe decreased markedly.
Working on the modernization of the device, the experts brought the mass of the main moving elements to a minimum, thereby not sacrificing quality and durability. How did you manage to achieve such a result? They supplied parts that are much lighter than their counterparts. Of course, the cost of the motor has not decreased, but reliability has grown. A new oil pump was put into the engine. It lubricates all working parts and engine elements very well. Such significant changes have led to the fact that the motor resource of the device has increased by 30%!
By redesigning the cooling system, the developers managed to achieve even greater efficiency. Due to the fact that the engine has a system of separate cooling modules for the cylinder head and the block with cylinders, the device warms up much faster. This system protects the motor from overheating.
As soon as the first engine was created internal combustion, almost immediately began work on its improvement. As the main task, the developers have identified for themselves such as reducing the overall dimensions of the motor itself, increasing its power and increasing the stability of the car. Thus, the first boxer engine appeared, which solved a sufficient number of problems, but not all.
Initially, the civil automotive industry did not accept the boxer type of motor, and it was installed exclusively on military equipment. The first civilian car, where a new type of engine was installed, was the Beetle from the Volkswagen concern. Over time, when more than 20 million of these cars were produced, the idea of using an opposition engine was adopted by brands such as Porsche and Subaru.
Opposition engine - design differences
Despite the fact that the scheme of the boxer engine, in principle, is one, there can be two options for its execution. This is due to the fact that the same technical solution, namely the horizontal arrangement of the cylinders, is implemented different ways.
Boxer engine
Such a motor is designed in such a way that the pistons are constantly located at a certain distance from each other - when one is at the maximum distance from the engine, then its “neighbor” occupies exactly the same position. This type of boxer engine got its name because of the similarity of piston movements with the movements of a boxer. It is this motor that the Subaru concern very widely uses in its cars.
Motor "OROS"
Such an engine is arranged somewhat differently. Its revival has begun quite recently, helped in no small measure by the investments of Bill Gates.
This is a standard two-stroke boxer engine, in each cylinder of which there are two pistons that move towards each other. All pistons are mounted on the same shaft. One of them is for intake combustible mixture into the combustion chamber, the second - to remove exhaust gases. This arrangement allowed the designers to abandon the drive mechanism for the valves, as well as the cylinder head itself. It is worth noting such an advantage as the operation of all pistons with one crankshaft.
Are there any advantages to a boxer engine
Like any other type, a boxer engine has advantages and disadvantages, which are due to design features. Despite some negative sides, the advantages of this type of motors are very numerous.
There are disadvantages too
What does a boxer engine mean in terms of its merits is clear to many, but nevertheless there are a number of disadvantages due to which such a motor is not yet installed on all cars produced today.
Some features of modern opponents
Since its development and installation of the first boxer engine on a Volkswagen in 1938, this type of engine has undergone major modernization. Four-cylinder engines are currently the most widely used - they are the most environmentally friendly, compact and economical in terms of fuel consumption. In many ways, this was the result of many years of painstaking work of engineers who embodied a sufficient number of unique developments in such motors:
The high reliability and power of the boxer engine is also evidenced by the fact that this particular type of engine was installed on the Soviet T-64 tank, and later on the T-72. Only such a boxer engine, the principle of which has changed little since then, was able to provide high power with its relatively small overall dimensions. For reference, only he could issue about seven hundred Horse power at 2 thousand revolutions and a volume of 13.6 liters. mass interesting facts You can learn about the work of opposition motors by watching the video:
How to Avoid Costly Boxer Engine Repairs
Any boxer engine has pros and cons, which is quite natural. To avoid problems, the elimination of which may require very serious material costs, it makes sense to heed the advice of specialists and operate the car with a boxer engine installed correctly. The first thing you should pay close attention to is the exact observance of the terms of maintenance, which should be carried out at specialized stations and only by qualified personnel.
Great care must be taken when choosing engine oil. Preference should be given only famous brands, acquisition do either in specialized stores with an impeccable reputation, or in branded centers after-sales service. Using a low-quality product can cause a lot of trouble for an overly economical driver. The same can be said about the quality of fuel. Fuel containing a large amount of "unauthorized" additives seriously reduces engine life, leading to the need for expensive repair work.
Many car owners who purchase vehicles with a boxer engine, they have heard about a high-quality and efficient cooling system, so they don’t really get hung up on this moment. You should not drive the engine mercilessly, especially in the warm season - the most advanced cooling system may not be able to cope with its task. To a large extent, it contributes to difficult cooling and the absence of periodic washing of the engine - the accumulated dirt on the motor significantly complicates heat transfer, contributing to excessive heating.
Despite some difficulties, the boxer engine proved to be excellent, significantly increasing driving comfort and safety. It should be noted that the prevailing opinion about the extreme high cost of owning a car with such an engine is clearly exaggerated. For example, consider the Subaru brand, which has been producing cars with this type of engine for a long time - they have never been among the cars with excessive expensive service, and many cars with standard engines cost their owners much more. Significant savings on fuel also affect here, which is much less required - depending on the specific car model, fuel savings can reach up to 50%.
Eleven years later, Fuji Heavy, which develops engines for Subaru models, introduced the third generation of the branded opponent. The Japanese plan to equip the entire the lineup stamps. boxer engine Subaru is equipped with four cylinders and is still gasoline.
Both a more powerful turbocharged version and a classic naturally aspirated engine are available, according to the taste and finances of the client. The new version of Subaru's horizontally opposed engine was endowed with all the advantages of previous generations, but there were also weak sides opponent.
Advantages of opponents
Upon closer inspection, it turns out that the Subarovsky engine is not compact, but simply relatively symmetrical and flat - it seemed to be “smeared” on engine compartment. It is clear that no matter how hard the engineers try, the dimensions of a 4-cylinder internal combustion engine cannot be less than a certain volume. The motor plate is really short and flat, but very wide.
The motors of the B6, R6, R8, V12 layout are fully balanced. Opposite B4 in this list, alas, does not appear. However, the B4 unit has an advantage in terms of vibration load, but there is no serious difference with the traditional in-line four.
According to Subaru's advertising, the cars have a low center of gravity, which contributes to amazing stability and handling at high speeds. Of course, on a racing or rally track, this is an obvious plus. But with daily driving around the city with traffic jams, a low center is not always a plus. When shaking on hatches, potholes and speed bumps, when hobbled along a broken primer - are these opposite virtues civil car? A significant role for speed exercises is played by suspension, pavement and tire condition. Unfortunately, it is difficult to brag about the quality of coverage, and other factors depend on the owner.
By itself, the boxer and the box installed longitudinally do not create a symmetrical weight distribution, however rear wheels get a slightly larger share of the load. And here come the shortcomings. The longitudinal layout of the engine on a front-wheel drive machine must ensure that the engine is positioned in front of the axle, being completely in the front overhang. Therefore, Subaru cars get a long overhang, sometimes not yielding to Audi with an in-line engine and a similar layout.
Disadvantages of Subaru engines
There is a curious feature in the geometry of engine cylinders - when the hone grid is in its normal state, and the cylinder begins to turn into an ellipse. True, aluminum cylinder blocks with cast-iron liners and different expansion ratios have never been considered ideal.
Engines are worn out by excessive consumption of oil, and regardless of age - older cars from the first wave of foreign cars and people from Subaru car dealerships, still smelling of fresh plastics, can stand in line for the master. The horizontal layout of the cylinders itself contributes to the waste, on occasion the turbines do not give up their share of oil, and, of course, this leads to the standard disease of the occurrence of the rings. The air flow sensor is quickly and willingly covered with dirt on models from any manufacturer. Unfortunately, good MAP sensors are a thing of the past.
At the moment, Subaru's boxer engine has many modifications. It is not clear why a company with only four mass-produced cars should produce so many versions, updating them almost every year. For example, nine engines are provided for one Impreza. And the number of modifications reaches forty.
They differ from each other not only in the type of fuel consumed, but also in design features. For example, there is a great variety in the arrangement of cylinders. Each option has its strengths and weaknesses. In this case, the pros and cons of a boxer engine will be considered.
Read in this article
What are the features of a boxer engine
AT piston engines internal combustion (and there are also rotary ones), the placement of cylinders can be different in relation to each other: under acute angle, in a row, star-shaped and so on. In the case of a boxer, the cylinders are in the same plane and placed one opposite the other at an angle of 180 degrees. Unlike many in-line engines, the boxer unit often has two, as well as a vertical distribution. There are several types of boxer engines. Among them, the most famous are:
- Boxer ("Boxer"). It differs in that the pistons located in front of each other move like boxers in the ring. That is, when one of them is at the highest point, the second occupies the lowest position. They are all the time equally removed from each other;
- OROS - Opposed Piston Opposed Cylinder. The principle of operation in this case is that the pistons are in pairs in one cylinder (upper and lower piston). They move towards each other, rotating the crankshaft.
- 5 TDF. This is a two stroke tank engine. Soviet-made, which was used on the T-64 and T-72 tanks. Interesting feature of this unit is its multi-fuel. The main fuel for him is diesel fuel. However, with the help of a special switch on the high-pressure fuel pump, it was possible to start the operation mode on gasoline or on a mixture of gasoline with kerosene and diesel fuel, and the engine could also run on jet fuel. True, it was also necessary to correct the ignition angle (injection timing).
Many companies were actively involved in the development of power units. For example, Volkswagen has paid attention to this type of units since the mid-30s of the last century. These were not just experiments, but the desire to develop their own boxer motor, reduce the level of vibrations that occur during the operation of a traditional V-shaped or in-line engine, etc. By the way, Volkswagen engineers also applied their development in the legendary Volkswagen car Beetle. And since the 60s, boxer engines have been actively used Japanese company Subaru, which was engaged in development in parallel with the Germans.
Advantages of the boxer ICE
By and large, the operation of a boxer engine does not differ from the principle of operation of units of other designs. However, such an arrangement of cylinders has certain advantages, as well as disadvantages.
- The most noticeable advantage of the power plants under consideration is the almost complete absence of vibration during operation. This effect is achieved due to the arrangement, which balance each other. This not only adds comfort, but also significantly increases the service life. This is where the second "plus" comes from;
- Impressive boxer engine life. There is evidence that quite often the mileage to the first overhaul was at least 500 thousand kilometers. Of course, the driving style makes its own significant adjustments. And, nevertheless, the overhaul period is quite long. However, quite often one can meet the statements of specialists and motorists that 800-900 thousand before the first is nothing more than a beautiful fairy tale;
- The motors of the design considered in this article provide vehicles with a low center of gravity. This quality is especially appreciated in powerful sports cars. After all, passing turns at high speeds, it is very important to maintain stability;
- Also, one cannot fail to mention the space saving under the hood. Although this point will seem controversial to many, because winning in height, you need to make the hood wider or longer.
Here, perhaps, are all the essential advantages of the opponents. Now we need to consider the disadvantages, which, unfortunately, are somewhat larger.
The main differences, as well as the advantages and disadvantages of 8-valve engines compared to 16 valve engines. Which power unit is better to choose.
After the creation of the first internal combustion engine, questions arose almost immediately about its improvement and increase in power. The first engine was single-cylinder, and the simplest solution immediately suggested itself to increase its power - to increase the number of cylinders. But the next steps in the development of internal combustion engines were not so obvious, since these several cylinders can be arranged in different ways - vertically in a row one after the other, at an angle or horizontally. This last option was called the boxer engine, i.e. engine, the cylinders of which are located horizontally opposite (opposite) each other.
Boxer engine options
However, even such a simple technical solution - to place the engine cylinders horizontally opposite each other, can be implemented in several ways. When such a boxer engine is running, its pistons can move in many different ways.
boxer boxer
During the operation of such a motor, the pistons are always at a distance relative to each other, and each works in its own cylinder - if one is located at the maximum distance from the axis of the engine, then the other, neighboring one, occupies a similar position.
This order of work resembles the movements of a boxer, which is why he received the name "boxer". Very often uses similar Subaru boxer engines. The described engine is shown in the photo below. 
OPOC, the revival of old ideas
Another construction principle implements a boxer engine of the OPOC type. Today they are beginning to develop again thanks to the investments of the notorious Bill Gates. The device of such an engine is shown in the figure below. 
This boxer engine is a two-stroke. The figure clearly shows that there are two pistons in the cylinder, and they are fixed on one crankshaft (in the figure they are indicated as red and blue). Red provides the intake of the mixture, and blue - the release of combustion products. From the design of such a boxer engine, the cylinder head and the valve drive mechanism disappeared. In addition, the advantage of such an opponent is that the pistons work on one crankshaft.
All this significantly reduced the weight of the boxer engine and significantly expanded the scope of its use. Another feature is that it can be either diesel or petrol. It must be made clear that, like any two stroke engine, he needs to purge the cylinders. For this, an electric motor powered by an external source is used. When the boxer engine enters the mode, the electric motor is turned off and the air supply device turns into a turbocharger.
Considering the design of such a boxer motor, its advantages should be noted: an increase in efficiency provided by the fact that expanding gases press on two pistons, and not on the wall of the combustion chamber, as well as increased force on the shaft. In addition, each piston travels a shorter distance, which reduces friction and, consequently, losses.
Considering other advantages that such a boxer engine promises, it is worth noting that the manufacturer reports that when it is used as a diesel engine, then:
- such an engine is fifty to thirty percent lighter than a conventional turbodiesel;
- such a power unit contains fifty percent fewer parts than a conventional diesel engine;
- takes up fifty to forty-five percent less space under the hood;
- 50-45% more economical.
However, it should be borne in mind that such a boxer power unit is still quite crude, which means that the noted advantages reflect to a greater extent the expectations of its developers.
Boxer tank engine
Yes, there was such an engine, this is the 5TDF, designed for the T-64 tanks, as well as subsequent T-72s and others. Then it provided the necessary power for the given dimensions. A similar boxer engine and its device are shown in the figure below. 
As can be seen from the figure, his pistons are located in one cylinder and move in the opposite direction, but each work on its own crankshaft. With a minimum distance between the pistons, a combustion chamber is formed between them, where the fuel is ignited. There is a boxer engine, both petrol and diesel. By analogy with OPOC, turbocharging is used to supply air to the cylinders, as well as remove exhaust gases.
The used principle of the oncoming movement of the pistons made it possible to simplify the design, provide power and compactness power plant. So, a similar diesel boxer power unit at two thousand revolutions, a volume of thirteen and six tenths of a liter produced seven hundred horsepower, while taking up a minimum of space.
What is good and bad for an opponent?
It should be noted that in the history of the car, many manufacturers at different times used the boxer engine, trying to realize the advantages provided by it. However, at the moment, more often than others, SUBARU uses such engines in its cars. 
It should be noted right away that it is the device of the boxer power unit that provides its advantages when installed on a machine:
- low center of gravity of the car, which gives it additional stability when driving;
- reduction of both noise and vibration due to the movement of the pistons towards, due to which the boxer engine is considered quieter than similar in-line engines;
- a significant resource, reaching a million kilometers with proper operation.
However, everything is not always good, there are minuses and shortcomings in the opposition. Of these, it is worth noting:
- repair of such a motor is very difficult;
- the engine device is also quite complex, and accordingly, it has a high price;
- maintenance costs are high, and the maintenance itself is extremely costly and inconvenient, requiring highly qualified performers;
- increased oil consumption during operation.
Despite the noted disadvantages and shortcomings, a number of cars (already mentioned SUBARU and some Porshe models) are equipped with boxer power units. We must think that manufacturers accurately weigh their advantages and disadvantages and consciously go for the use of such a motor.
For internal combustion engines, the arrangement of cylinders horizontally is only one of options construction, but nevertheless, in this case, the resulting boxer engine has great potential and significant prospects for use in a car.