Function of an Exhaust System | Full Details.

What is the function of an exhaust system? In this article, I will discuss the Function of an Exhaust System. 

Function of an Exhaust System
The function of an Exhaust System

The exhaust system is an essential component in a vehicle that is responsible for directing exhaust gases away from the engine and safely releasing them into the environment. Its primary function is to reduce the harmful emissions produced by the engine, which include carbon monoxide, nitrogen oxides, and hydrocarbons.

Function of an Exhaust System- 

Function of an Exhaust System– The exhaust system also helps to improve engine performance and fuel efficiency by reducing back pressure and providing a more efficient flow of exhaust gases. Additionally, it helps to reduce noise levels produced by the engine, ensuring that the vehicle operates quietly and smoothly. Overall, the exhaust system is a crucial part of a vehicle, and without it, the engine’s performance, fuel efficiency, and safety could be compromised. 

The air-fuel mixture bums in the combustion chamber, pressure rises and the piston gets a power impulse by which it moves downward giving the motion to the crankshaft. For the continuous running of the engine, the fresh charge is to come over and over again inside the cylinder and the burnt (or exhaust) gases are to be removed from the cylinder. The exhaust system collects the exhaust gases from the cylinder and conducts them to the rear of the vehicle, where they are discharged into the atmosphere. The exhaust system does so with a minimum power loss, noise, or vibration, and transfer of heat to the vehicle body. The exhaust system consists of exhaust from the cylinder (or cylinders of a multi-cylinder engine). The exhaust pipe connects the exhaust manifold and the muffler. On another side of the mufflers, a tailpipe or outlet pipe is connected which discharges the exhaust gases into the atmosphere.

Single exhaust system of V-8 engine.
The single exhaust system of the V-8 engine.
This FIg shows a single exhaust system of a V-8 engine. It consists of only one muffler and one tailpipe. In some cases, a dual exhaust system is used, each unit of which has an exhaust manifold, muffler, and piping.
When the length of the exhaust system is particularly long, or where improved silencing is required, an additional muffler or expansion box may be fitted in advance of the muffler. In order to reduce the fire risk and avoid vapor look n the fuel pipes, it is advantageous to fit the exhaust manifold will be fitted on the opposite side of the engine to the inlet manifold. 

To prevent power losses, the exhaust system must present a minimum resistance to the flow of the exhaust gases, as such build up back pressure in the exhaust system that opposes the working pressure in the cylinders. 

Exhaust system for a six-cylinder engine.
Exhaust system for a six-cylinder engine.

The overall length of the exhaust system should be kept as short as possible, with the minimum number of bends. The ratio of the tailpipe diameter to the length is important for maximum silencing efficiency. 

Exhaust Manifold

The exhaust manifold is a tube for carrying the exhaust gases away from the engine cylinders. It collects exhaust gases from the exhaust ports of the various cylinders and conducts them to a central exhaust passage.

Exhaust manifold.
Exhaust manifold.

The exhaust manifold is usually made of cast iron. It is bolted to the side of the cylinder block on L-head engines and to the side of the cylinder head on I-head engines. On V-8 engines, there are two exhaust manifolds, one for each bank of cylinders. On some V-8 engines, each manifold is connected to a separate exhaust pipe, muffler, and tailpipe. On others, they are connected by a crossover pipe and exhaust through a common muffler and tailpipe. Fig. shows an exhaust manifold for an eight-cylinder in-line passenger car engine.

The exhaust manifolds are designed to avoid overlapping of exhaust strokes, as far as possible, thus keeping the back pressure to a minimum. This is often done by dividing the exhaust manifold into two or more branches so that two cylinders will not exhaust into the same branch at the same time. Large radius bends are provided in the design to eliminate any restriction to the flow. A heat tube may also be provided to furnish heat to the built-in automatic choke unit of the carburetor.
The center portion of the exhaust manifold is often connected to the intake manifold of an in-line engine through a heat trap and exhaust damper, except where the intake manifold is water-heated. The damper is controlled thermostatically to deflect the exhaust gases around the intake manifold. When the engine is cold all the exhaust gases pass around the intake manifold. When the engine is warmed up, a part of the exhaust gases goes around it; and when the engine is fully warmed up none of the exhaust gases goes around the intake manifold, but goes directly to the exhaust pipe, as shown in Fig.

Heat control valve operation.
Heat control valve operation.


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