A boxer engine is an engine with a horizontal piston arrangement, that is, the pistons move horizontally relative to the car body. This arrangement is often found on Subaru engines,.
In a boxer engine, the pistons are located at an angle of 180°, and their movement is in the same horizontal plane relative to each other. Neighboring pistons in a boxer engine are equally spaced relative to each other. The second name of the “opposite” is “boxer”, this name was given to the motors for the peculiarity of the movement of the pistons, which resembles a boxer fight. The sound of the boxer motor is difficult to confuse with the sound of a conventional motor.
Unlike the classic V-shaped, in a boxer motor, each piston with a connecting rod is located on a separate crankshaft crankpin. In V-shaped motors, the pistons and connecting rods are on the same crankpin, so if one piston is at top dead center (TDC), then the second is at bottom TDC.
The main undeniable "pluses" of the boxer engine:
- Minimum vibration during operation;
- Low center of gravity;
- High degree of safety in the event of a frontal collision. In the event of a frontal impact, the engine goes under the car, which allows the driver and passenger to survive the accident and get out of it with minimal injury.
- Excellent stability, a car that is called "holds the road" and copes well with even the tightest turns.
- The location in the same plane with the transmission provides the most efficient power transfer.
At the same time, with all the above advantages, the boxer motor has another problem, due to the design features, the motor is affected by inertia forces that try to turn it around a vertical axis. The weight of this type of engine is often much lower than that of V-shaped counterparts, this can be achieved by installing
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.
In piston 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 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 Soviet-made two-stroke tank engine, which was used on the T-64 and T-72 tanks. An 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 Beetle. And since the 60s, boxer engines have been actively used by the 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 before 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 cars 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.
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 English, 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 better power transfer. 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 repairs;
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 Volkswagen engineers began to improve the V-shaped and in-line engine. In the sixties, the idea was intercepted by the Japanese company 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 should be the ideal engine in order to provide excellent driving? There is only one answer - Subaru's horizontally opposed engine.
Today, the boxer engine practically personifies this brand, although it is also used not only in Subaru, but also in cars of other brands, for example Porsche (albeit much less often).
By the way, fans of Soviet motorcycle classics most likely remember motorcycles with an opposed engine arrangement, such as the Ural and Dnepr, and their characteristic sound of a running engine. The sound of a boxer engine is another feature and a marketing advantage for car manufacturers.
Thus, Subaru makes this sound and its racing achievements a kind of “highlight” of its cars, which distinguishes them from all others, which, in turn, has the most positive effect on sales of cars of this brand.
Principle of operation
The principle of operation of the horizontally opposed Subaru engine is practically no different from the well-known internal combustion engine. The working strokes proceed at the same speed as with the vertical arrangement of the engine.
Flaws
- The main disadvantage is the difficulty of repairing boxer engines. Some of these engines are beyond repair at all unless removed from the engine bay. Until not least without a specialized tool. If you do not want to spend a huge amount of time, then contact the professionals. It is worth remembering that for such a procedure you will have to pay a rather large amount, which is not surprising. After all, not every specialist knows the structure of a boxer engine and its features;
- It is very difficult to find a specialized mechanic;
- A complex device requires a large financial investment in terms of new parts. That is, in order to buy the necessary part, you will have to pay a large amount;
- Increased oil consumption.
Advantages
An engine design with pistons on either side of the crankshaft at an angle of 180 degrees creates a huge number of advantages:
- With a horizontal arrangement of the cylinders against each other, the inertia forces arising from the movement of the pistons are mutually extinguished. Due to this, the engine has good balance and low vibration.
- The low level of vibrations makes it possible to get by with counterweights of small mass and not to install balancing shafts. As a result, the engine consumes less fuel and has better responsiveness.
- The low vibration level also makes it possible to obtain large cylinder diameters, which makes it easier to create high-speed engines for sports cars.
- Inertia relative to the vertical axis of the car is less, which increases the speed of response to control.
- The low engine height and low center of gravity further improve responsiveness and vehicle stability.
- The possibility of obtaining a large diameter of cylinders facilitates the creation of high-speed engines for sports cars.
- The design of the horizontally opposed engine has greater rigidity, which reduces mechanical losses during engine operation. This increases the life of the engine.
Safety
passive safety. In the event of a severe frontal collision, the flat boxer engine is more easily guided under the vehicle floor, thereby reducing impact energy transmitted to the passenger compartment.
Pedestrian safety. The boxer engine is flat, leaving space between the hard parts of the engine and the comparatively soft bonnet. This allows you to more effectively absorb the impact energy when hitting a pedestrian.
High stability during sharp maneuvers
The lightweight aluminum alloy engine has a low center of gravity, which ensures low inertia relative to the longitudinal axis of the car and low rolls.
The advantage of a low center of gravity can be demonstrated using the example of a metronome. If you move the weight to the lower position, the pendulum will swing quickly. When the weight is moved to the upper position, the vibrations will slow down. Thus, the advantage of a low center of gravity is most pronounced when passing through a bunch of tight turns at high speed.
Controllability
The low center of gravity and the longitudinal arrangement of the short engine make it possible to reduce not only rolls in a turn, but also the moment of inertia relative to the vertical axis of the car, which has a positive effect on understeer.
When the driver turns the steering wheel to change direction, the vehicle's center of rotation is closer to the rear of the vehicle. For vehicles of equal mass, a shorter distance from the center of rotation to the center of gravity means easier turning. That is why the layout with a low-mounted engine and a gearbox docked longitudinally with it is preferable.
In contrast to roll, which is a natural consequence of making a turn, the movement caused by turning the steering wheel can be mistaken for active movement as it is dictated by the driver.
In the metronome example, such an active movement is analogous to stopping the metronome pendulum with your finger and pushing it in the opposite direction. If the pendulum weight is in the down position, you will need less force to push it the other way.
