What is the difference between 2 valves and 4 valves per cylinder?

[LoganMarie]

2 valves refer to an engine with one intake and one exhaust valve, totaling 2 valves, while 4 valves refer to an engine with two intake and two exhaust valves, totaling 4 valves. 2-valve engines are mostly used in small-displacement, low-speed engines, whereas 4-valve engines are commonly found in large-displacement, high-speed engines. These differences lie in the valve train mechanisms of the engines, but the principles remain the same. Here is some additional information: 1. Valves: Valves refer to the intake and exhaust valves of a cylinder. The intake valve is directly connected to the intake manifold and serves as the entry point for the engine to draw in the air-fuel mixture (or fresh air). The exhaust valve is connected to the exhaust manifold and serves as the exit for the engine to expel combustion waste gases. 2. Function: Valves are specifically responsible for introducing air into the engine and expelling the post-combustion exhaust gases. Structurally, they are divided into intake and exhaust valves. The intake valve's role is to draw air into the engine to mix with fuel for combustion, while the exhaust valve's role is to expel the post-combustion waste gases and dissipate heat.