An engine is a machine that converts chemical energy into mechanical energy, and its conversion process is actually a working cycle process. Simply put, it is the process of burning fuel in the cylinder to generate kinetic energy, driving the piston in the engine cylinder to move back and forth, thereby driving the connecting rod connected to the piston and the crank connected to the connecting rod to move back and forth in a circular motion around the center of the crankshaft, and outputting power.

According to different sources of power, automotive engines can be divided into diesel engines, gasoline engines, electric vehicle motors, and hybrid engines. According to the working mode of the intake system, it can be divided into four types: naturally aspirated, turbocharged, mechanically supercharged, and dual turbocharged.

According to the piston movement mode, it can be divided into two types: reciprocating piston internal combustion engines and rotary piston engines.

According to cylinder arrangement, it is divided into inline engines, V-type engines, W-type engines, and horizontally opposed engines.

According to the number of cylinders, it can be divided into single cylinder engines and multi cylinder engines. Modern cars often use three cylinder, four cylinder, six cylinder, and eight cylinder engines.

According to different cooling methods, it can be divided into water-cooled engines and air-cooled engines. Water cooled engines have uniform cooling, reliable operation, and good cooling effect, and are widely used in modern automotive engines.

According to the number of strokes, it can be divided into four stroke internal combustion engines and two stroke internal combustion engines.

Four stroke internal combustion engines are widely used in automotive engines. Classified by fuel supply method: carburetor engine, electronic injection engine, and cylinder direct injection engine.