Exhaust manifold, also known as an exhaust header, is a component in an internal combustion engine that collects and channels the exhaust gases produced by the engine's cylinders. It is typically made of metal, such as cast iron or stainless steel, and is mounted on the engine's cylinder head.

The primary function of an exhaust manifold is to gather the individual streams of exhaust gases from each cylinder and combine them into a single outlet. Each cylinder in the engine has an exhaust port, and the manifold collects the gases emitted from these ports, directing them towards the exhaust system.

Here are the main functions of an exhaust manifold:

1.Gas Collection: The exhaust manifold is positioned directly at the engine's cylinder head and is designed to collect the exhaust gases produced during the combustion process. Each cylinder has its own exhaust port, and the manifold gathers the gases from all the cylinders into a single outlet.

2.Gas Combining: The manifold combines the individual streams of exhaust gases from each cylinder into a single flow. By merging the gases together, it creates a more efficient path for the exhaust to exit the engine, reducing backpressure and improving overall engine performance.

3.Heat Dissipation: The exhaust gases expelled from the engine contain a significant amount of heat energy. The manifold's metal construction helps dissipate this heat by providing a large surface area for heat transfer. Effective heat dissipation prevents excessive temperature buildup in the engine compartment, which can lead to damage or reduced performance.

4.Emissions Control: In modern vehicles, the exhaust manifold often incorporates an oxygen sensor(s) or other emission control devices. These sensors monitor the oxygen content in the exhaust gases, providing feedback to the engine control unit (ECU). The ECU uses this information to adjust the air-fuel mixture, optimizing combustion efficiency and reducing harmful emissions.

5.Connection to Exhaust System: The exhaust manifold serves as a connection point between the engine and the rest of the exhaust system. It directs the exhaust gases into the downstream components, such as the catalytic converter, muffler, and tailpipe. The manifold's design may include flanges or connections for easy installation and secure attachment to the exhaust system components.

Overall, the exhaust manifold plays a vital role in collecting, merging, and directing the engine's exhaust gases, while also contributing to heat dissipation and emissions control. Its proper functioning is essential for the efficient operation of the engine and compliance with emission regulations.