What type of valves are used in a 4-stroke cycle engine to operate the port openings?

In a 4-stroke cycle engine, poppet valves are used to control the intake and exhaust of gases. These valves open and close at specific times during the engine cycle to allow fresh air-fuel mixture to enter the combustion chamber and to let exhaust gases exit after combustion. Poppet valves operate with a spring mechanism and have a cylindrical shape that fits into a machined seat, allowing for a tight seal when closed, which is crucial for maintaining the engine's efficiency and performance.

The functioning of poppet valves is synchronized with the movement of the engine's camshaft, which precisely times their opening and closing in accordance with the engine's cycle of intake, compression, power, and exhaust strokes. This timing is key to ensuring that the engine operates smoothly and effectively.

Other valve types, such as butterfly valves and ball valves, serve different applications and are not suited for this specific function in a 4-stroke cycle engine. Butterfly valves are commonly found in throttle applications and are used to regulate air flow but do not operate in the same manner as poppet valves. Ball valves are primarily used in fluid control systems due to their simple on/off operation and are also not designed for the timing and operation required in engine cycles. Throttle valves