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What is the exhaust manifold

The exhaust manifold is one of the parts of the implements of the motor (or ICE), designed to collect exhaust gases into a single tube of several cylinders.

The structure of the exhaust manifold

The exhaustion collector is defaced, as a rule,from cast iron. On the one hand, it is attached to the catalyst (or to the exhaust pipe), on the other - directly to the ICE. Due to the location peculiarities, the collector operates under extreme conditions. During the operation of the engine, the exhaust gases are heated to a temperature of several thousand degrees. After the motor is muffled, their cooling is sufficiently rapid, which inevitably leads to the formation of condensate. As a result, rust quickly appears on the collector.

an exhaust manifold
What functions does the exhaust manifold perform:

- removal from the combustion chamber of exhaust gases;
- filling and purging the combustion chamber. This provides resonant waves of exhaust. When the intake valve opens, the pressure in the manifold is within the normal range, and in the combustion chamber the working mixture is under pressure. After the exhaust valve has been opened, a wave forms due to a 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 start of the exhaust stroke, thereby helping to leave the cylinder of the next portion of the exhaust gases.

Resonance (standing waves) appear in the ICE pipeat a sufficiently wide 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 engine speed, the faster the gases exit, the sooner returns and moves the wave, which achieves a shorter cycle.

spider exhaust manifold
To create favorable and identical conditions for each cylinder, it is necessary that for each cylinder there is a personal exhaust pipe (to form standing waves and separate the cylinders).

To avoid burns and to increase fire safety, the exhaust manifold is usually enclosed by a metal screen.

Solid or tubular manifolds

Tubular manifolds can significantly improvecapacity ICE, but they are not always the best choice for an accelerated motor. Although it is these reservoirs that are more effective in the mid-range rev range. However, if the motor is running at low speed, good performance may be provided by collectors made of cast iron (solid ones). They are more compact and less prone to leakage.
exhaust manifold
Auto Tuning and Sports

In the field of auto-tuning and motor sport, the importancehas an exhaust manifold. "Spider" is the name he received for his appearance. Sometimes on race cars there is no exhaust manifold - each cylinder has its own exhaust pipe without a silencer and a catalyst of a certain length. For autotuning, there are now many models of manifolds with different characteristics that significantly affect engine performance. It is also possible to make an exhaust manifold by hand.

Virtually all of these parts are made ofceramics or stainless steel. The exhaust manifold of ceramics is lighter, but with strong heating, cracks can appear on it, which will negatively affect the operation of the ICE.

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