Basic parameters of internal combustion engine

Displacement
First, let's look at the most common engine parameter - engine displacement. Engine displacement refers to the total working volume of each cylinder in the engine, usually expressed in liters (L). The working volume of a cylinder is the volume of gas swept by the piston from top dead center to bottom dead center, also known as single-cylinder displacement. It depends on the cylinder diameter and piston stroke. Engine displacement is a very important engine parameter; it represents the size of the engine better than the cylinder diameter and number. Many engine indicators are closely related to displacement. Generally speaking, the larger the displacement, the greater the engine output power.
Number of Cylinders
After understanding the displacement, let's look at other common parameters of the engine. Many novice car enthusiasts often reflect that they see "L4", "V6", "V8", "W12", etc. in the engine section of car information and hope to understand their meaning. These all indicate the arrangement and number of cylinders in the engine. Commonly used car engine cylinder numbers include 3, 4, 6, 8, 10, and 12.
Cylinder Arrangement
Cylinder arrangement, 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 by the engine.
Currently, the mainstream engine cylinder arrangement methods are:
L: Inline
V: V-shaped arrangement
Other non-mainstream cylinder layouts:
W: W-shaped arrangement
H: Horizontally opposed engine
Inline Engine
Inline engines, usually abbreviated as L, such as L4 representing an inline 4-cylinder. The inline layout is currently the most widely used cylinder arrangement, especially in engines with displacements below 2.5 liters. In this layout, all cylinders are arranged side by side at the same angle on a plane, using only one cylinder head. At the same time, the structure of the cylinder block and crankshaft is relatively simple, such as the cylinder column type.
Specifically, we commonly have four types: L3, L4, L5, and L6 (the number represents the number of cylinders). The advantages of this layout engine are small size, high stability, good low-speed torque characteristics, and low fuel consumption, which also means lower manufacturing costs. At the same time, the inline cylinder layout engine is relatively compact and can adapt to more flexible layouts. It is also convenient to arrange the turbocharger device. However, its main disadvantage is that the engine itself has lower power and is not suitable for models with 6 cylinders or more.
V-type engine:
The so-called V-type engine, simply put, is to divide all cylinders into two groups and arrange adjacent cylinders at a certain angle (angle between the center lines of the left and right cylinders) γ < 180° together to form a plane. The two groups of cylinders are at a certain angle. Viewed from the side (usually at an angle of 60°), the cylinders are V-shaped, hence the name V-type engine.
Compared with the inline layout, the V-type engine shortens the length and height of the vehicle body, and the lower installation position also allows designers to design a vehicle body with a lower drag coefficient. At the same time, due to the opposed arrangement of the cylinders, some vibrations can also be offset, making the engine run more smoothly. For example, some mid-to-high-end models that pursue a comfortable and smooth driving experience still insist on using large-displacement V-type layout engines instead of the more technologically advanced "small-displacement inline layout engine + turbocharger" power combination.
W-type engine:
Many people believe that, just as the cylinder arrangement of a V-type engine is V-shaped, the cylinder arrangement of a W-type engine must also be W-shaped. In fact, this is only an approximate W-shaped arrangement. Strictly speaking, it should also belong to a V-type engine, at least a variant of a V-type engine.
W-type engine. The W-type engine is a unique engine technology of Volkswagen Group in Germany. The W-type engine is formed by slightly misaligning the cylinders on both sides of the V-type engine. Or, the cylinder arrangement of the W-type engine is composed of two small V-types forming a large V-type, and the two groups of V-type engines share a crankshaft. Strictly speaking, the W-type engine should also be a variant of the V-type engine.
Compared with the V-type engine, the W-type engine can be made shorter, and the crankshaft can also be shorter, which can save the space occupied by the engine. At the same time, its weight can be lighter, but the width is larger, making the engine compartment more spacious.
The biggest problem with the W-type engine is that it is divided into two parts, and inevitable significant vibrations will occur during operation. To address this issue, Volkswagen has designed two counter-rotating balance shafts on the W-type engine, so that the vibrations of the two parts cancel each other out internally.