displacement
First, let's take a look at the most common engine parameter - engine displacement. The engine displacement is the total working volume of each cylinder in the engine, usually expressed in liters (L). The working volume of a cylinder refers to the volume of gas swept by the piston from top dead center to bottom dead center, also known as the single cylinder displacement, which depends on the cylinder diameter and piston stroke. Engine displacement is a very important engine parameter, which better represents the size of the engine than cylinder diameter and number. Many indicators of the engine are closely related to the displacement. Generally speaking, the larger the displacement, the greater the engine output power.
Number of cylinders
After understanding the displacement, let's take a look at other common engine parameters. Many novice car enthusiasts often report seeing words such as "L4", "V6", "V8", "W12" in the engine section of their car information, hoping to understand what they mean. These all indicate the arrangement and number of cylinders in the engine. The commonly used cylinder numbers for automotive engines include 3, 4, 6, 8, 10, 12, etc.
Cylinder arrangement
The arrangement of cylinders, as the name suggests, refers to the arrangement of each cylinder in a multi cylinder internal combustion engine. Simply put, it refers to the queue of cylinders discharged from an engine.
At present, the mainstream engine cylinder arrangement is:
L: Inline
V: V-shaped arrangement
Other non mainstream cylinder arrangements:
W: W-shaped arrangement
H: Horizontally opposed engine
Inline engine:
Inline engine, usually abbreviated as L, for example L4 represents inline 4-cylinder. The inline layout is the most widely used cylinder arrangement nowadays, especially on engines with displacements below 2.5L. All cylinders in this layout of the engine are arranged side by side at the same angle in a plane, and only one cylinder head is used. At the same time, the structure of the cylinder block and crankshaft is relatively simple, such as the cylinders standing in a column.
Specifically, we commonly see four types: L3, L4, L5, and L6 (numbers represent the number of cylinders). The advantages of this layout engine are compact size, high stability, good low-speed torque characteristics, and less fuel consumption, which also means lower manufacturing costs. At the same time, engines with inline cylinder layouts are also relatively compact and can adapt to more flexible layouts. It is also convenient for arranging supercharger devices. But its main drawback is that the engine itself has a lower power and is not suitable for models equipped with 6 or more cylinders.
V-type engine:
The so-called V-type engine, in simple terms, divides all cylinders into two groups and arranges adjacent cylinders together at a certain angle (the angle between the centerline of the left and right cylinders) γ< 180 °, forming a plane with two sets of cylinders at an angle, the cylinders appear in a V-shaped shape when viewed from the side (usually at an angle of 60 °), hence the name V-type engine.
Compared with the inline layout, the V-shaped engine shortens the length and height of the body, and the lower installation position allows designers to design a body with a lower drag coefficient. At the same time, thanks to the opposed arrangement of cylinders, it can also offset some vibrations, making the engine run smoother. For example, some mid to high end models that pursue a comfortable and smooth driving experience still insist on using a large displacement V-shaped layout engine instead of the more advanced technology of a "small displacement inline layout engine+turbocharger" power combination.
W-type engine:
Many people think that just like the cylinders of a V-shaped engine are arranged in a V-shaped shape, the cylinder arrangement of a W-shaped engine must also be in a W-shaped shape. In fact, it is only an approximate W-shaped arrangement, strictly speaking, it should also belong to a V-shaped engine, at least a variant of a V-shaped engine.
W-type engine, W-type engine is the exclusive engine technology of Volkswagen in Germany. The W-type engine is formed by slightly misaligning the cylinders on each side of the V-type engine. Or rather, the cylinder arrangement of a W-type engine is composed of two small V-shapes forming a large V-shape, with two sets of V-type engines sharing the same crankshaft. Strictly speaking, the W-type engine should also be a variant of the V-type engine.
Compared to the V-type engine, the W-type engine can be made shorter, and the crankshaft can also be shorter, which can save space occupied by the engine. At the same time, it can be lighter in weight, but its width is larger, making the engine compartment fuller.
The biggest problem with the W-type engine is that it is divided into two parts as a whole, which inevitably causes significant vibration during operation. In response to this issue, Volkswagen has designed two counter rotating balance shafts on the W-type engine, allowing the vibrations of the two parts to cancel each other out internally.
Horizontal opposed engine:
When introducing the cylinder V-shaped arrangement engine above, it has been mentioned that the angle formed by the V-shaped layout is usually 60 ° (the angle between the centerline of the left and right cylinders) γ< The cylinder angle of a horizontally opposed engine is 180 degrees. However, the manufacturing cost and process difficulty of horizontally opposed engines are quite high, so currently only two manufacturers in the world, Porsche and Subaru, are using them.
VR engine:
The VR engine is a proprietary product of Volkswagen. In 1991, Volkswagen developed a 15 ° angle V6 2.8L engine called VR6, which was installed on the third-generation Golf. This type of engine has a compact structure, a width close to that of an inline engine, and a length no longer than that of an inline 4-cylinder engine.
As is well known, for a V-type 6-cylinder engine, a 60 degree angle is the optimal design, which has been proven through countless scientific experiments. Therefore, the vast majority of V6 engines adopt this layout form. But in order to accommodate the V6 engine in a smaller space, Volkswagen Group has taken a different approach and developed a smaller VR6 engine with an angle of 15 degrees. From the perspective of power parameters, it is not inferior to a regular V6 engine, but it exposed obvious shaking problems at the beginning of development. Although a series of balancing and stabilizing measures have significantly improved the problem. But this still cannot go beyond changing its structural characteristics, just like the vibration of a regular inline engine is usually greater than that of a V-shaped engine, the VR6 with a smaller angle determines from its structure that its vibration will be greater than that of the V6. Models such as Volkswagen's Golf R32 and EOS have all been equipped with this engine.
  The characteristic of VR engines is their small size, making them very suitable for the front engine platform of Volkswagen series. Because Volkswagen's front engine front wheel drive chassis is designed in a longitudinal manner, and the engine is located in front of the front axle, the engine cannot be too long or it is difficult to arrange the front suspension. This engine is very compact. Although it is a V-cylinder engine, due to the close proximity of the two rows of cylinders, only one cylinder head is needed to handle it, which is much lower in cost than a V6 engine with a 90 degree and 60 degree angle (because a regular V-cylinder engine must process two cylinder heads, and if it is a DOHC V-cylinder engine, it also needs to process four camshafts, so the cost is very high).