Why does Subaru have such a characteristic growling exhaust sound? What is a boxer engine - pros and cons Boxer sound

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. Adjacent pistons in a boxer engine are positioned identically in relation to each other. The second name for “opposite engines” is “boxer”, the motors received this name for the peculiarity of the movement of the pistons, which resembles a boxer’s fight. The sound of a boxer engine is difficult to confuse with the sound of a conventional engine.

Unlike the classic V-shaped engine, in a boxer engine each piston with a connecting rod is located on a separate crank pin of the crankshaft. In V-shaped engines, 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 “advantages” of the boxer engine:

1. Minimal vibration during operation;
2. Low center of gravity;
3. 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 injuries.
4. Excellent stability, the car, as they say, “holds the road” and copes well with even the sharpest turns.
5. The location in the same plane with the transmission ensures 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, inertial forces act on the motor, which try to rotate it around the vertical axis. The weight of this type of engine is often much lower than that of V-shaped analogues, this can be achieved thanks to the installation

What do we know about the boxer engine? The fact that the pistons in it move horizontally. That this engine is the face of Subaru cars. Perhaps that's all. Let's find out a little more.

A boxer engine is one of the internal combustion engine layouts 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 resembles a boxing match, so another name for the 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 crankpin of the crankshaft. A boxer engine always has an even number of cylinders (2, 4, 6, 8, 10, 12). The most common currently available are four- and six-cylinder boxer engines.

The boxer engine should not be confused with the V-twin engine and the cylinder angle of 180°. Although externally similar, in such an engine adjacent pistons with connecting rods are located on the same connecting rod journal. Therefore, when one piston reaches top dead center, the other is at bottom dead center.

The undeniable advantages of the boxer engine are a low center of gravity, minimal vibration during operation and a high level of safety in a frontal collision.

The center of gravity of the boxer engine is shifted downwards to achieve better stability and controllability of the car. The low-mounted engine is aligned with the transmission, resulting in more efficient power transfer.

A boxer engine is almost completely vibration-free (there is only a moment from second-order inertia forces, tending to turn the engine around a vertical axis). The mutually coordinated movement of adjacent pistons ensures smooth engine operation. The boxer engine's mass balance allows the crankshaft to be mounted on three main bearings (instead of the usual five), significantly reducing engine length and weight.

Boxer engine better meets the requirements passive safety. In the event of a frontal collision, the engine goes down under the car and, thereby, saves the lives of passengers in the cabin. An equally important advantage of a boxer engine for drivers is the characteristic sound of its operation, which differs from other internal combustion engines.

Unfortunately, boxer engine is not without its shortcomings. The most serious, in our opinion, is the high labor intensity repair work, associated with a design feature of the engine. Yes, to complete individual repairs the engine must be removed from the vehicle. Some sources note that the horizontal movement of the piston leads to uneven wear cylinder liner and, as a result, increased consumption oils Due to certain overall dimensions The boxer engine is installed on the car only longitudinally.

Currently, boxer engines are being developed and installed in their cars by Subaru and Porsche. Previously, the boxer engine could be seen in cars from Alfa Romeo, Citroen, Chevrolet, Honda, Lancia, Toyota, Volkswagen and even Ferrari.

Subaru has used boxer engines since 1963. These are four- and six-cylinder Boxer. The history of four-cylinder engines from Subaru goes back three generations: the series E.A.(1966-1994); series EJ(1989-1998, crankshaft on 5 main bearings, 1999-2010, crankshaft on three main bearings); series FB(since 2010). Six-cylinder Boxers went into production a little later - series ER(1987-1991), series E.G.(1992-1997), series EZ(since 1999).

The vast majority of boxer engines are gasoline engines with distributed fuel injection and overhead valve timing. They have one (SOHC) or two (DOHC) camshafts, which are driven from the crankshaft by a timing belt or chain. Despite the different number of camshafts, the engines employ a four-valve gas exchange scheme. A number of engines are turbocharged.

The third-generation four-cylinder Boxer is simpler, more compact, economical and harmless. To reduce fuel consumption, reduce emissions, increase torque and expand its limits, many progressive technical solutions are used in new engines:

• the compression ratio is increased by increasing the piston stroke and reducing the volume of the combustion chamber;
• the weight of moving parts (connecting rod, piston, crankshaft) is reduced due to forging;
• on camshaft X the intake and exhaust valves use a variable valve timing system (AVCS active valve control system);
• a new oil pump has been applied, providing high quality lubricants and increasing engine life;
• A cooling system with separate circuits is used to cool the cylinder block and the cylinder head.

In 2008, Subaru first introduced diesel boxer engine. The four-cylinder engine with a volume of 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 car 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.

They differ from each other not only in the type of fuel consumed, but also in design features. For example, there is great variety in the arrangement of cylinders. Each option has its own strengths and weak sides. In this case, the pros and cons of the boxer engine will be considered.

In piston engines internal combustion(and there are also rotary ones) the placement of the 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 placed opposite each other at an angle of 180 degrees. Unlike many in-line engines, the boxer unit often has two, as well as 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 extreme top point, the second occupies the extreme bottom position. They are always equally distant from one another;
• OROS — Opposed Piston Opposed Cylinder. The principle of operation in this case is that the pistons are located 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. Interesting feature This unit is multi-fuel. The main fuel for it is diesel fuel. However, using a special switch on the high-pressure fuel pump, it was possible to start operating on gasoline or a mixture of gasoline with kerosene and diesel fuel, and the engine could also run on jet fuel. True, it was also necessary to adjust 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 unit since the mid-30s of the last century. These were not just experiments, but a desire to develop our own boxer engine, to reduce the level of vibrations that arise during the operation of a traditional V-twin or in-line engine, etc. By the way, Volkswagen engineers used their development in the legendary Volkswagen car Beetle. And since the 60s, boxer engines began to be actively used Japanese company Subaru, which was engaged in development in parallel with the Germans.

Advantages of an opposed internal combustion engine

By and large, the operation of a boxer engine is no different from the principle of operation of units of other designs. However, this arrangement of cylinders has its certain advantages, as well as disadvantages.

• The most noticeable advantage of the considered power plants There is considered to be 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 service life. This is where the second “plus” comes from;
• Impressive life of the boxer engine. There is evidence that quite often the mileage before the first major overhaul was at least 500 thousand kilometers. Of course, driving style makes significant adjustments. And, nevertheless, the time between repairs is quite long. However, quite often one can come across statements from experts and car enthusiasts that 800-900 thousand before the first one is nothing more than a beautiful fairy tale;
• The motors of the design discussed in this article provide cars with a low center of gravity. This quality is especially appreciated in powerful sports cars. After all, when taking turns 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 to gain in height, you need to make the hood wider or longer.

That, perhaps, is all the significant advantages of opposition speakers. Now we need to consider the disadvantages, of which, unfortunately, there are several more.

The main differences, as well as the advantages and disadvantages of 8 valve motors compared to 16 valve engines. Which power unit better to choose.

What should it be perfect engine to provide a superior driving experience? 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 frequently).

By the way, fans of Soviet motorcycle classics most likely remember motorcycles with an opposed engine, such as the Ural and Dnepr, and their characteristic sound of a running engine. The sound of a boxer engine is another of its features 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 operating principle of the Subaru horizontally opposed engine is practically no different from the well-known internal combustion engine. Power strokes proceed at the same speed as with a vertical engine.

Flaws

• The main disadvantage is the difficulty of repairing boxer engines. Some of these engines are completely beyond repair unless removed from engine compartment. Not yet without a specialized tool. If you do not want to spend a huge amount of time, then turn to professionals. It is worth remembering that for such a procedure you will have to pay a fairly 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 large financial investments 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

The engine design, in which the pistons are located on either side of the crankshaft at an angle of 180 degrees, creates a huge number of advantages:

• When the cylinders are arranged horizontally opposite each other, the inertial forces arising during the movement of the pistons are mutually canceled out. Due to this, the engine has good balance and low vibration levels.
• The low level of vibrations allows you to get by with counterweights of small mass and not install balance shafts. As a result, the engine consumes less fuel and is more responsive.
• The low level of vibration also makes it possible to obtain large cylinder diameters, which facilitates the creation of high-speed engines for sports cars.
• The 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 enhance vehicle stability.
• The ability to obtain large cylinder diameters facilitates the creation of high-speed engines for sports cars.
• The design of a horizontally opposed engine has greater rigidity, which reduces mechanical losses during engine operation. Thanks to this, the engine resource increases.

Safety

Passive safety. In the event of a serious frontal collision, the flat-boxer engine is more easily directed under the vehicle's floor, thereby reducing the impact energy transferred to the passenger compartment.

Pedestrian safety. The boxer engine has a flat shape, leaving space between the hard engine parts and the relatively soft hood. This allows you to more effectively absorb impact energy when hitting a pedestrian.

High stability during sharp maneuvers

The lightweight aluminum alloy engine has a low center of gravity, which provides low inertia relative to the longitudinal axis of the vehicle and low roll.

The benefit of a low center of gravity can be demonstrated with the example of a metronome. If you move the weight to the lower position, the pendulum will swing quickly. When moving the weight to the upper position, the oscillations will slow down. Thus, the advantage of a low center of gravity is most clearly manifested when passing a bunch of sharp turns at high speed.

Controllability

The low center of gravity and the longitudinal position of the short engine make it possible to reduce not only roll when turning, but also the moment of inertia relative to the vertical axis of the car, which has a positive effect on turning.

When the driver turns the steering wheel to change direction, the vehicle's center of rotation is positioned toward the rear of the vehicle. For cars of equal mass, a smaller distance from the center of rotation to the center of gravity means easier turning. That is why a layout with a low-mounted engine and a gearbox longitudinally coupled to it is preferable.

In contrast to roll, which is a natural consequence of turning, the movement caused by turning the steering wheel can be mistaken for active movement, since it is commanded by the driver.

In the metronome example, this active movement is analogous to stopping the metronome pendulum with your finger and pushing it in the opposite direction. If the pendulum bob is in the down position, you will need less force to push it the other way.