Today, many types of various internal combustion engines are installed on cars, which differ from each other in the type of fuel used and the method of ignition ( gasoline, diesel ), as well as in layout (in-line, V-shaped, boxer, etc.).
If we ignore the most common in-line “fours” and “sixes” with a longitudinal and transverse arrangement, then boxer engine deserve special attention.
As a rule, most drivers have a very superficial understanding of this type of internal combustion engine. Most of the knowledge comes down to well-known information, that is, that in boxer engines, the pistons lie in a horizontal plane (opposite each other), and the engine itself has become massive thanks to the Japanese brand Subaru.
In this article, we intend to talk in more detail about what kind of boxer engine device, what are the strengths and weaknesses of such an engine, and also what features a diesel boxer engine has.
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Boxer internal combustion engine: general information
So, we note right away that the opponents are both gasoline and diesel. We add that until recently, such engines were exclusively gasoline, that is, a diesel boxer engine appeared relatively recently.
The very concept of “boxer engine” is actually a definition of the layout scheme. In such an engine, the pistons are located at an angle of 180 degrees (camber angle). It is also noteworthy that during engine operation, adjacent pistons occupy the same position, being at TDC or BDC (top and bottom dead center).
It is important to understand that a boxer engine is different from a V-engine, which can also have a similar camber angle. Visually, such internal combustion engines will be similar, however, in a V-shaped engine, adjacent pistons and connecting rods are located on the same crankpin. This means that if one piston is at TDC, the other goes down at BDC.
Subaru’s boxer engine is also called the “boxer” due to the unique movement of the pistons. These ICEs get an even number of cylinders, with 4 and 6 cylinder options being the most common.
As for design features, in such an engine, each piston with a connecting rod is attached to a separate crankshaft crankpin. These engines are also more complicated than in-line ones, since they have two cylinder heads, each with its own separate gasket and manifolds.
Also, the boxer has a larger number of camshafts and a complex scheme for implementing their drive. Given these features, boxer internal combustion engines are mass-produced by only a few manufacturers, among which Subaru engineers have advanced the furthest in this direction.
Boxer Diesel Engine
In 2008, the appearance of a boxer diesel engine was noted, which was serially installed on the Subaru model. Moreover, the Japanese then generally introduced the world’s first diesel boxer, since no automaker had previously produced such an engine.
The diesel boxer four-cylinder engine received a displacement of 2.0 liters, power was 150 hp, and the torque indicator was recorded at an impressive mark of 350 Nm. As you know, it is the moment characteristic, and not power, that plays a paramount role.
The engine was also equipped with a Common Rail fuel injection system and a turbocharger was installed. A variable geometry turbine was used as a turbocharger, which allowed the engine to almost completely get rid of the turbo lag effect and provide confident traction in a wide speed range.
The specified boxer diesel engine was planned to be installed under the hoods of the Subaru Legacy and Outback, as well as to launch the legendary Subaru Forester in a diesel version.
Problems and Reliability of The Boxer Engine
If we talk about what advantages of a boxer engine can attract the attention of motorists against the background of other developments, then it is worth noting the low center of gravity and the almost complete absence of vibrations during the operation of such an internal combustion engine in different modes.
As for the diesel version, which at the same time also promises significant fuel savings, then the minimum of vibrations allows us to count on a significant increase in comfort during the operation of a diesel car. It’s no secret that even modern diesel engines such as TDI, etc. usually more noisy and vibration-loaded compared to gasoline counterparts.
Passive safety is also worth noting, since the boxer engine“goes” down better during a frontal impact, thereby avoiding significant deformation of the driver’s capsule. Also, a downward shift in the center of gravity when using this type of internal combustion engine provides improved handling and makes the car more stable.
Even in the device of this type of engine, the crankshaft is mounted on a smaller number of main plain bearings, as a result, the total weight of the engine is reduced. It turns out that the boxer engine runs smoothly, without vibrations, is on the same axis as the gearbox and, thanks to this, it gives out more power, a car with such an engine is better controlled, and the level of passive safety is increased.
If we touch upon the shortcomings of the boxer engine, then the complexity of its maintenance and the high cost of repairs come to the fore, especially in the CIS. The fact is that in order to carry out a series of manipulations, the engine must simply be removed. Still, such engines require a lot of space in the engine compartment. This makes it difficult to access the elements of the engine itself and attachments.
Also, some experts point out that despite the rather large resource of the boxer engine, the presence and operation of the pistons in a horizontal position leads to the fact that the cylinder walls wear out unevenly. The result is increased engine oil consumption.
What is the result
As you can see, today the vast majority of boxer engines are gasoline versions that are equipped with distributed injection, can be both atmospheric and turbocharged. At the same time, Subaru also introduced a diesel version with Common Rail.
Also, all later versions of the boxers are high-tech forced engines, which allow you to get maximum power with significant fuel savings. The latest generation engines have a high compression ratio due to an increase in the piston stroke at the same time as a decrease in the volume of the combustion chamber.
Many more parts in the boxer engine are forged, which makes them light and strong at the same time. The active use of variable valve timing systems provides elasticity in different modes of operation of the internal combustion engine.
Finally, we note that Subaru has vast experience and a number of its own unique developments in the production of boxer engines. This means that the creation of a diesel boxer using all advanced technologies has allowed motorists to purchase a car that is equipped with a reliable, modern, economical and at the same time powerful diesel engine.
