The principle of operation of a boxer engine, advantages and disadvantages. Subaru Boxer Engine: Pros and Cons Boxer vs Inline
After the creation of the first ICE, questions arose almost immediately about its improvement and increase in power. The first engine was single-cylinder, and the simplest solution immediately suggested itself, allowing to increase its power - to increase the number of cylinders. But the next steps in the development of the internal combustion engine were not so obvious, since these several cylinders can be arranged in different ways - vertically in a row one after another, at an angle or horizontally. This last version was called the boxer engine, i.e. an engine whose cylinders are located horizontally, opposite (opposite) each other.
Boxer engine options
However, even such a simple technical solution - placing the engine cylinders horizontally opposite each other - can be implemented in several ways. When such a boxer engine is running, its pistons can move different ways.
Boxer boxer
During the operation of such a motor, the pistons are always at a distance from each other, and each works in its own cylinder - if one is located at the maximum distance from the engine axis, then the other, adjacent, occupies a similar position.
This way of working resembles the movement of a boxer, which is why it is called "boxer". Very often uses similar boxer engines Subaru. The described engine is shown in the photo below. 
OPOC, reviving old ideas
Another construction principle implements an opposed 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 a motor is shown in the figure below. 
This boxer engine is a two-stroke engine. The figure clearly shows that there are two pistons in the cylinder, and they are fixed on one crankshaft (in the figure they are designated as red and blue). Red provides an inlet for the mixture, and blue provides an outlet for combustion products. From the design of such a boxer engine, the cylinder head and valve drive mechanism disappeared. In addition, the advantage of such a boxer 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 gasoline. It is imperative to clarify that like anyone two-stroke engine, he needs to purge the cylinders. For this, an electric motor powered from an external source is used. When the boxer engine is on mode, the electric motor is shut off and the air supply is converted to a turbocharger.
Considering the design of such a boxer engine, it is necessary to note its advantages: an increase in efficiency provided by the fact that the expanding gases press on two pistons, and not on the wall of the combustion chamber, as well as an increased force on the shaft. In addition, each piston travels a shorter distance, which reduces friction and therefore losses.
Considering other advantages that a similar boxer engine promises, it is worth noting - 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 fifty to forty five percent less space under the hood;
- more economical by fifty to forty five percent.
However, it should be borne in mind that such an opposed 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, developed for the T-64 tanks, as well as the subsequent T-72 and others. Then he provided the necessary power for the given dimensions. A similar boxer engine and its structure are shown in the figure below. 
As can be seen from the figure, its 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 gasoline and diesel. By analogy with OPOC, turbocharging is used to supply air to the cylinders as well as to remove the exhaust gases.
The principle of counter movement of pistons used made it possible to simplify the design, ensure the power and compactness of the power plant. So, a similar diesel boxer power unit at two thousand revolutions, a volume of thirteen and six tenths of a liter gave out seven hundred Horse power, while taking up a minimum of space.
What is good and bad about oppositor?
It should be noted that in the history of the car, many manufacturers in different time used a boxer engine in an attempt to realize the benefits it provided. However, at the moment, SUBARU uses such motors more often than others on their cars. 
It should be noted right away that it is the device of the opposed power unit that provides its advantages when installed on a car:
- 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 the opposite, 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 also disadvantages and disadvantages of the opposed one. 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 service itself is extremely costly and inconvenient, requires highly qualified performers;
- increased oil consumption during operation.
Despite the noted disadvantages and disadvantages, a number of cars (the already mentioned SUBARU and some Porshe models) are equipped with opposed power units. One must think that manufacturers quite accurately weigh their advantages and disadvantages and deliberately go for the use of such a motor.
For internal combustion engines, the arrangement of the cylinders horizontally is only one of the possible options construction, but nevertheless, in this case, the resulting boxer engine is distinguished by great capabilities and significant prospects for use in a car.
The first engine was barely built internal combustion, almost immediately started 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 civilian automotive industry did not perceive opposed type motor, and it was installed exclusively on military equipment... The first civil car where it was installed new type the engine became "Beetle" from the concern "Volkswagen". Over time, when more than 20 million of these cars were already produced, the idea of using an opposition engine was adopted by such brands as Porsche and Subaru.
Opposition engine - design differences
Despite the fact that the diagram of the boxer engine is, in principle, 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 in different ways.
Boxer engine
Such a motor is designed in such a way that the pistons are constantly spaced from each other at a certain distance - when one is at the maximum distance from the engine, then its "neighbor" takes exactly the same position. This type of boxer motor got its name due to the similarity of piston movements with the movements of a boxer. It is such a motor that is very widely used by the Subaru concern in its cars.
Motor "OROS"
Such an engine has a slightly different structure. Its renaissance has begun quite recently, helped in no small part by Bill Gates' investments.
It is a standard two-stroke boxer engine with two pistons in each cylinder that move towards each other. All pistons are mounted on the same shaft. One of them is intended for the admission of the combustible mixture into the combustion chamber, the second is for the removal of 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, the boxer engine has advantages and disadvantages, which are due to design features. Despite some negative aspects, the advantages of this type of motor are quite numerous.
Disadvantages are also present
What does a boxer engine mean in terms of its advantages is clear to many, but nevertheless there are a number of disadvantages due to which such a motor has not yet been installed on all cars produced today.
Some features of modern boxers
Since its development and the 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 widespread - 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:
O high reliability and the power of the boxer engine is evidenced by the fact that this type of engine was installed on the Soviet T-64 tank, and later on on the T-72. Only such a boxer engine, the operating 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 give out about seven hundred horsepower at 2 thousand revolutions and a volume of 13.6 liters. Mass interesting facts you can find out about the work of opposition motors by watching the video:
How to avoid costly boxer engine repairs
Any boxer engine has pluses and minuses, which is quite natural. To avoid the occurrence of problems, the elimination of which may require very serious material costs, it makes sense to heed the advice of specialists and operate a car with an installed boxer engine correctly. The first thing that you should pay close attention to is the exact adherence to the deadlines Maintenance, which should be carried out at specialized stations and only by qualified personnel.
Great care should be taken when choosing engine oil... Preference should be given only to famous brands, make the purchase either in specialized stores with an impeccable reputation, or in brand centers service... Using a low-quality product can cause a lot of trouble for an overly economical driver. The same can be said for the quality of the fuel. Fuel containing a large amount of "unauthorized" additives seriously reduces the engine life, leading to the need for costly renovation works.
Many car owners purchasing vehicles with a boxer engine, have heard about a high-quality and efficient cooling system, so they don't really get hung up on this point. You should not mercilessly drive the engine, especially in the warm season - the most advanced cooling system may not cope with its task. To a large extent, it contributes to difficult cooling and the absence of periodic cleaning of the engine - accumulating dirt on the motor significantly complicates heat transfer, contributing to excessive heating.
Despite some challenges, the boxer engine has proven itself to be of great benefit to 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 motors cost their owners much more. This is also reflected in the significant savings on fuel, which is required much less - depending on specific model auto fuel savings can be up to 50%.
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 the cylinders. Each option has its own strengths and weak sides... 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
In reciprocating internal combustion engines (and there are also rotary ones), the placement of cylinders can be different in relation to each other: at an acute angle, in one row, star-shaped, and so on. In the case of an opposed cylinder, the cylinders are in the same plane and are placed opposite each other at an angle of 180 degrees. Unlike many in-line engines, the opposed unit often has two and also vertical distribution. There are several types of boxer engines. Among them, the most famous are:
- 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 in extreme top point, the second is in the lowest position. They are all the time equally distant from one another;
- OPOS - 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 by rotating the crankshaft.
- 5 THF. This is a Soviet-made two-stroke tank engine that was used on the T-64 and T-72 tanks. An interesting feature of this unit is its multi-fuel capacity. The main fuel for him is diesel fuel. However, using a special switch on fuel pump high pressure, it was possible to start the mode of operation 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 required to correct the ignition angle (injection timing).
Many companies were actively involved in the development of power units. For example, Volkswagen paid attention this type units since the mid-30s of the last century. These were not just experiments, but the desire to develop our own boxer engine, to reduce the level of vibrations that arise during the operation of a traditional V-shaped or in-line engine, etc. By the way, Volkswagen engineers applied their development in the legendary Volkswagen car Beetle. And since the 60s, boxer engines have been actively used. Japanese company Subaru, which was developing in parallel with the Germans.
Benefits of an opposed internal combustion engine
By and large, the operation of a boxer engine does not differ from the principle of operation of units of other designs. However, this arrangement of cylinders has certain advantages as well as disadvantages.
- The most noticeable advantage of the considered power plants the almost complete absence of vibration during operation is considered. This effect is achieved through arrangements that balance each other. This not only adds comfort, but also significantly increases the service life. From here comes the second "plus";
- Impressive flat engine life. There is evidence that quite often the run to the first overhaul was at least 500 thousand kilometers. Of course, the driving style makes its own significant adjustments. And, nevertheless, the turnaround time is quite long. However, all the time you can find the assertions of experts 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 cars with a low center of gravity. This quality is especially appreciated in powerful sports cars. Indeed, passing bends at high speeds, it is very important to maintain stability;
- Also, one cannot fail to mention the saving of space under the hood. Although this point will seem controversial to many, because winning in height, you need to make the hood wider or longer.
These are, perhaps, all the essential advantages of opposites. 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 motors compared to 16 valve motors... Which power unit is better to choose.
Modern piston engines Internal combustion (ICE) can be classified based on criteria such as the type of fuel consumed and the location of the cylinders. If with the division of engines based on the type of fuel, everything is more or less clear even to people who are very far from technology, then with the division according to the arrangement of the cylinders, everything is not so obvious. In this article, we will look at one of the types of internal combustion engines with an unusual arrangement of cylinders, namely a boxer engine. Here you will learn about what a boxer engine is, how it works, what its pros and cons, and where it is used.
The design and features of the boxer engine
The diagram of the boxer engine
Opposed internal combustion engines are called, the camber angle of the cylinders of which is 180 °. The pistons in them move in a horizontal plane, moreover, mirror-like in relation to each other. This means that they reach their highest point at the same time. By the way, this is one of the main differences between opposed power units from the more common V-shaped ones: in them, the pistons move synchronously (when one of them is at the top point, the second is at the bottom).
Thanks to this arrangement of cylinders, the boxer engines have a low center of gravity. In addition, their height is significantly less than that of the V-shaped, they are "flatter" and take up less space in engine compartment... One of distinctive features boxer engines are the presence of two gas distribution mechanisms (they have one crankshaft, like V-shaped ones, most often they have one). As for the principle of operation of these motors, it is exactly the same as for all other internal combustion engines: the movement of the pistons driving the crankshaft is carried out due to the pressure of the gases formed during the combustion of the fuel mixture.
Types of boxer engines
Today there are three main types of boxer engines:
- Boxer;
- OPOC;
- 5 THF.
They differ from each other mainly in the way in which the pistons move in them.
Boxer. In boxer engines of this type, each piston is located in its own cylinder, and they are located at a certain distance from each other, which always remains constant. This is precisely the main feature of such power units. Since in the process of functioning, the movement of their pistons resembles the movement of boxers in the ring, they got the name Boxer.
OPOC. This abbreviation stands for Opposed Piston Opposed Cylinder, and the design feature of this type of boxer engine is that there are two pistons in each of the cylinders. They move towards each other. OPOC type boxer engines are two-stroke, they do not have cylinder heads and valve actuators. Thanks to this design, these power units are lightweight, and they are both gasoline and diesel.
5 THF. This type of boxer engine is domestic development... At one time, it was created specifically for installation on T-64 tanks, a little later it was used in the T-72. Just like in the opposed OPOC engine, its cylinders contain two pistons that move towards each other, but unlike it, each of them has its own crankshaft... Combustion chambers in 5 TDF boxer engines are located between the pistons, they work both on gasoline and on diesel fuel... Now these power units are no longer produced.
Pros and cons of boxer engines
Boxer engine crankshaft and pistons
Like other types of internal combustion engines, boxer powertrains have both pros and cons. As for the pluses, one of the most significant of them is the very low level vibrations during operation. This is what these motors owe to the opposed arrangement of their pistons. The fact is that when moving, they mutually balance each other, and the imbalance of forces that leads to vibrations is almost completely absent.
This advantage of boxer engines entails another significant plus: since there are practically no vibrations, the wear of moving parts is much slower than in, say, V-shaped engines. Accordingly, the resource of such motors is very large: practice shows that the value of their mileage before overhaul is about half a million kilometers. Some owners of cars with boxer engines claim that this figure is even higher in practice, ranging from 600,000 to 700,000 kilometers.
Another plus of power units of this type is the low center of gravity. That is why they are often installed on sports cars... When cornering at high speeds, boxer engines provide increased vehicle stability. In addition, as mentioned above, their low height can be considered an advantage of motors of this type. In fairness, it should be noted that at the same time they are somewhat wider than power units of other types (for example, the same V-shaped motors).
As for the disadvantages of boxer engines, the main ones are the following: high price and the complexity of the repair. The design of such motors implies high precision in the manufacture of many of their main elements, the use of expensive high-strength materials. In addition, their assembly and adjustment is much more complicated than similar procedures for V-shaped or in-line internal combustion engines. Diagnostics and troubleshooting of boxer engines is possible only with specialized equipment and specially trained personnel. It goes without saying that even minor repairs to such motors are not cheap for the owners of the cars on which they are installed.
Also, a significant drawback of boxer engines is considered a significant oil consumption. However, in terms of fuel consumption, they are still inferior to modern V-shaped and in-line power units.
Scope of application of boxer engines
Boxer engines are not nearly as widely used as V-shaped and in-line engines, but there is an automaker that has been installing these types of motors on their cars for half a century. This is a well-known Japanese firm Subaru. In addition, boxer units can be found on some Volkswagen models and Porsche, at one time they were equipped with Soviet motorcycles "Ural" and "Dnepr", Hungarian buses "Ikarus".
It should be noted that in last years interest in power units of this type has increased significantly. According to some reports, research and development on the improvement of OPOC boxer engines, carried out by a group of American engineers, is funded by Bill Gates.
Video on the topic
The novelty, presented in 2002, aroused great curiosity. The pros and cons of the Subaru boxer engine are assessed by almost every motorist, even if he is not going to change his iron horse or prefers models from other manufacturers.
Diesel fans are also showing interest, although the opposites are produced exclusively in the petrol interpretation - the promised advantages are tempting for everyone. Those who, by definition, love Subaru products, want to know what they have to deal with, since the concern intends to equip its models with only such engines in the near future.
The idea has been developed since the 60s of the last century, but somehow sluggishly and without enthusiasm. Now she is becoming the leading one for the company.
The pros and cons of a Subaru boxer engine are naturally determined by the peculiarities of its structure. The principle of its operation remains the same, the engine has not gone anywhere from the idea of internal combustion. But the design solution is original. And opposites are used only on Subaru and Porsche cars. Although not so long ago they were equipped with Honda, Alfa romeo, Chevrolet, Ferrari, Volkswagen and several others.
What is a boxer engine?
In classic motors, the cylinders have a vertical orientation and move, respectively, in the direction: up - down. In opposites, they are located horizontally, as a result of which the pistons move left - right. Since this movement strongly resembles a fight in the ring, this type of engine is popularly nicknamed "boxer".
It is interesting that the idea is not very original, but rather forgotten. Similar motors were aboard the departed Ikarus and Soviet motorcycles like the Dnieper, stood on some models of domestic tanks. Of course, Subaru developed a more perfect mechanism, but still they did not start from scratch at all.
Due to the horizontal arrangement of the cylinders, the engine seems to be more compact. However, this is an optical illusion: in terms of dimensions it is similar to traditional ones, it just has a lower height. But the width exceeds the inline engine by more than 2 times. Roughly speaking, it spread over the plane, which is why it looks smaller.
Advantageous sides of the opposition
Subaru also brings small dimensions to them, but we have already figured it out, so we cannot agree with the opinion of the company. The main advantages are given precisely by the horizontal orientation.
- Center of gravity shift... First, it is underestimated compared to in-line motors. Secondly, it is distributed along the axis. This gives better handling and stability;
- Reduced vibration... Conventional, even high-quality engines, to a certain extent transmit vibration waves to the body and to the interior. In opposites, the vibration of one piston is smoothed out and leveled by the oncoming movement of the second;
- Great resource... Boxers are theoretically rated for a million kilometers. Is this so - time will tell, but I want to believe;
- Enhanced security... And it has been proven by crash tests. At head-on collision conventional engines often go into the salon, breaking the front riders' legs. Boxer engine in case of a direct impact, they are displaced under the bottom, reducing the likelihood of death.
disadvantages
Perhaps it was they who led to the low prevalence of boxer engines. After all, many companies have gradually abandoned their use. And if in sports cars opposites are still found, then in, so to speak, everyday ones are quite rare.
- Engine self-maintenance is virtually zero... The complexity of its configuration leads to the fact that the owner can only change the oil himself. Even in order to replace or clean the candles, you will have to go to the service station. Anyone who dares to do this on their own has a high probability of seriously damaging the cylinder head.
- A flat-engine car is much more expensive to maintain than an in-line car. All auto works are estimated by masters higher, parts in price are 2-5 times higher than those for “rowers”.
- The opposed engine requires a catastrophic amount of oil. And if we reduce all the disadvantages to a single denominator, then we can say that they are too high monetary costs. That does not prevent people who have appreciated all the pros and cons of the Subaru boxer engine, to give preference to such models and still strive for the desired purchase.
