Function:
* Collects exhaust gases: It gathers the hot, spent gases from each cylinder after combustion and channels them into a single flow.
* Directs exhaust flow: The manifold directs the exhaust gases towards the rest of the exhaust system, including the catalytic converter, muffler, and tailpipe.
* Improves engine efficiency: By efficiently channeling exhaust gases, it helps improve engine performance and fuel economy.
Components and Construction:
* Pipes: The manifold consists of individual pipes, often called "runners," that connect to each cylinder's exhaust port.
* Collector: The runners converge into a single collector pipe, which then leads to the rest of the exhaust system.
* Materials: Exhaust manifolds are typically made of cast iron, steel, or even aluminum (in high-performance applications).
Types:
* Single-plane: Runners are all connected to a single point on the collector, creating a "pulse" that can improve low-end torque.
* Dual-plane: Runners are arranged in two groups, which helps spread exhaust pulses and can benefit high-rpm performance.
* Equal-length: Runners are all the same length to ensure consistent exhaust pulses, benefiting high-performance engines.
Importance:
* Performance: The design and construction of the exhaust manifold can significantly affect an engine's power, torque, and fuel efficiency.
* Durability: The manifold must withstand high temperatures and corrosive exhaust gases.
* Emissions: The manifold plays a role in directing exhaust flow for proper catalytic converter operation, minimizing emissions.
Common Issues:
* Cracks: High temperatures and vibration can cause cracks in the manifold.
* Leaks: Gaskets can wear out, causing leaks in the exhaust system.
* Corrosion: Exhaust gases can cause corrosion over time, especially in older vehicles.
In short, the exhaust manifold is an essential part of the engine's exhaust system, responsible for collecting and directing exhaust gases while contributing to overall performance and emissions control.
