The exhaust manifold is one of the parts of the attachment of the motor (or ICE), designed to collect exhaust gases into one pipe from several cylinders.
Exhaust manifold structure
The exhaust manifold is made, as a rule, of cast iron. On the one hand, it is attached to the catalyst (or to the exhaust pipe), on the other hand, directly to the internal combustion engine. Due to its location, the collector works in extreme conditions. During the operation of the internal combustion engine, the exhaust gases are heated to a temperature of several thousand degrees. After the engine is turned off, they are cooled quite quickly, which inevitably leads to the formation of condensate. As a result, rust quickly appears on the manifold.
What are the functions of the exhaust manifold:
- removal of exhaust gases from the combustion chamber;
- filling and blowing the combustion chamber. This is ensured by resonant exhaust waves. When the intake valve opens, the pressure in the manifold is within normal limits, and in the combustion chamber the working mixture is under pressure. After the exhaust valve has opened, a wave is generated due to the large pressure difference. It is reflected from the nearest obstacle (in conventional machines
it is a catalyst or resonator) and returns to the cylinder. Then, in the middle range of revolutions, this wave approaches the cylinder to the beginning of the exhaust stroke, thereby helping to leave the cylinder of the next portion of exhaust gases.
Resonance
(standing waves) appear in the ICE pipe at a wide enough range of revolutions. In this case, the wave propagates with the speed of exit from the cylinder, and not with the
speed of sound. For this reason, the higher the speed of the internal combustion engine, the faster the gases escape, the faster the wave returns and moves, having time to a shorter cycle.
To create favorable and uniform working conditions for each cylinder, it is necessary that each cylinder has a personal exhaust pipe (for the formation of standing waves and separation of the cylinders).
To avoid burns and to increase fire safety, the exhaust manifold is usually enclosed with a metal screen.
Solid or tubular manifolds
Tubular manifolds can significantly improve engine power, but they are not always the best choice for a
boosted motor. Although it is these collectors that are more efficient in mid-range revs. However, if the motor operates at low speeds, cast iron manifolds (solid) can give good performance. They are more compact and less prone to leaks.
Auto tuning and sport
In the field of auto tuning and motorsport, the exhaust manifold is important. "Spider" - this name he received for his appearance. Sometimes on
racing cars there is no exhaust manifold - each cylinder has its own exhaust pipe without a muffler and catalyst, a certain length. For auto tuning, many models of collectors with various characteristics that significantly affect the operation of the engine are now available. It is also possible to make the exhaust manifold with your own hands.
Almost all of these parts are made of ceramic or stainless steel. The ceramic exhaust manifold is lighter, but with strong heating, cracks may appear on it, which will negatively affect the operation of the internal combustion engine.