What is a car silencer and how does it work

Any car with an internal combustion engine is equipped with an exhaust system. One of its main elements is a silencer. Consider why it is needed in a car, how it works, what kind of device it is, as well as some tips for installing it.

What is a car muffler

A silencer is a volumetric bulb mounted at the end of an exhaust system. It is installed to damp sound waves arising during the operation of the motor. This is part of the entire exhaust system of a car.

In addition, before the exhaust gases are removed into the environment, they must be cooled. This is another feature of this part. Today there is a wide variety of silencers, which differ from each other not only in their efficiency, but also in design.

How does a car muffler work?

As the name implies, this part of the car's exhaust system is designed to dampen sound vibrations during engine operation. And due to the large volume, the exhaust gases are also cooled.

The main muffler consists of several chambers separated from each other, which are interconnected by tubes with perforation, offset relative to each other. When the flow of exhaust gases passes through the pipe and enters the first chamber, it hits the baffle, is reflected from it and then enters the second tube, passing into the next chamber. This is how sound waves are suppressed.

Today, there is a wide variety of stock mufflers, as well as options for car tuning. Each of these mufflers will differ not only in their size, but also in their internal structure. Despite this, the main task of this part remains sound suppression and exhaust gas cooling. The exception is straight-through mufflers, which, on the contrary, make the exhaust louder.

Silencer functions in the exhaust system

As all motorists know, if you remove the muffler in the car, it will roar louder than a racing car. This will seem funny to someone, however, such a car has no place in a quiet residential area.

In the exhaust system, the muffler performs the following functions:

• Extinguishes the exhaust gas exhaust sound. During engine operation, explosions are formed in the cylinders, which are accompanied by a loud noise.
• Reduces exhaust speed. Since the gases move at high speeds in the pipes, direct exhaust would cause significant inconvenience to passers-by and cars following such a machine.
• It cools exhaust gases. The internal combustion engine operates due to the energy that is released during the combustion of the air-fuel mixture. In the exhaust system, the temperature of these gases reaches several hundred degrees. In order not to injure people passing by the machine, as well as to avoid the arbitrary ignition of flammable objects, it is necessary to lower the temperature of the exhaust.
• Exhaust gas removal for redistribution of the body. The entire exhaust system is designed so that exhaust fumes do not accumulate under the car while it is standing still (for example, in a traffic jam or at a traffic light).

Inside the muffler, resistance is created for the movement of exhaust gases. It is important that this parameter does not exceed the permissible standards established by the engine manufacturer. Otherwise, the motor simply “suffocates” due to the fact that the exhaust system blocks the flow outlet.

Design, principle of operation and types of silencers

Car exhaust system consists of:

• Receiving pipe;
• Catalyst;
• Resonator;
• Main silencer.

The intake pipe is connected to the exhaust manifold. Its purpose is to combine all the conclusions from the motor into one cavity. In the catalyst, harmful substances that are part of the exhaust gases are neutralized. Thanks to this element, the exhaust is not so harmful to the environment.

Next in the system is a resonator. The main task of this element is to dampen the sound of exhaust gases. Outwardly, it resembles a smaller version of the main silencer.

Muffler Materials

All silencers are made of steel. Manufacturers use different grades of this material to increase the reliability and effectiveness of their products under extreme loads.

This part can be made of these types of steel:

• Carbon
• Aluminized;
• Galvanized;
• Stainless.

Most parts of the exhaust system include aluminum, so they have a longer service life. Carbon options, on the contrary, fail more quickly. Stainless versions are less common. However, they are among the most expensive types of silencers. Direct-flow silencers are often made from stainless steel, since the temperature of exhaust gases in such systems is much higher at the end of the highway.

Resonator device

A resonator is a flat or round metal can. It has several partitions in which perforated tubes are fixed. They are not installed opposite each other, but with an offset so that each of them faces the partition.

When exhaust gases enter the cavity from the main pipe, they hit the baffle. Reflecting, they partially dampen the sound wave of the incoming new portion of gases. Then they get into the next cavity chamber, where a similar process takes place. At the exit from the resonator, the sound is no longer so intermittent, but more like a hum, and not like shots.

Through the outlet pipe, the flow is directed to the silencer tank. It is structurally easier to place this element in the back of the machine, as there is more space.

Silencer device

The silencer itself has a similar device as the resonator. If you look at it in a section, then it has similar extinguishing chambers, only of a larger size. In addition to these elements, an absorber may be present in the silencer.

This is a special chamber in which perforated pipes pass. It is filled with porous material to absorb sound waves. As an absorber, metal shavings, mineral wool, or other porous material capable of withstanding high temperatures are used.

In fact, there is a wide variety of silencers. They differ from each other not only in the design of acoustic chambers, but also in the material from which they are made. According to the type of design, they distinguish:

• Restrictive. In such silencers, the outlet is a smaller diameter than the inlet. The bottom line is that the pulsating exhaust is suppressed due to the fact that it can not freely pass through the outlet, therefore it spreads throughout the cavity of the can.
• Mirrored. In such modifications, the exhaust gases hit the partition of the acoustic chamber, are reflected from it and enter the perforated pipe leading to the next chamber. Depending on the model, the details of such cameras may be more than two.
• Resonator. These silencers have up to 4 acoustic chambers. They are interconnected by a perforated pipe. The sound is suppressed due to the fact that sudden jumps are compensated by a large number of outlet openings along the highway. This design does not allow creating pressure inside the pipe, which reduces the flow rate.
• Absorbing. The principle of operation of such models has already been described a little earlier. This is a modification of the resonator type of silencers, only in addition a non-combustible porous filler is used to absorb sound waves.

Since each design has its own advantages and disadvantages, manufacturers often combine these types of silencers.

Resonant silencer design

One of the most complex designs is the resonant silencer model. The structure of such models is similar to the structure of the resonator, only the main element has a larger tank with an increased number of acoustic cavities.

Several perforated pipes are placed in the can cavity. They are not installed opposite each other, but in different planes so that the exhaust is scattered throughout the cavity. Thanks to this, the silencer suppresses all frequencies of sound waves. As expected, such varieties of elements of the exhaust system also create a certain resistance, which affects the power of the motor.

Features exhaust pipe silencer

A feature of all silencers is that when the temperature and sound effect are eliminated, the motor power partially decreases. A certain resistance is created inside the exhaust system. This factor affects the stroke of the piston in the exhaust stroke.

The greater this resistance, the more difficult it is for him to remove the combustion products. This means that the crankshaft will rotate at a lower speed. To solve this "problem", some craftsmen modernize the exhaust pipes, removing partitions from their cavities. Some generally remove the classic silencer, and install forward flow.

Naturally, in such models, exhaust gases are removed faster (energy is not wasted to overcome various barriers). As a result, engine power increases by about 7 percent. Even more power can be obtained by removing the catalyst from the system.

Before installing such a silencer in your car, there are two things to remember:

1. Within the city, you cannot use cars whose sound exceeds a certain level of decibels. In-line silencer does not fit into these parameters. A car with a similar exhaust system can make a real commotion in the courtyard of a multi-storey building. Such a system can equip a car that rides on tracks.
2. If a catalytic converter is removed in a vehicle, the level of pollution will increase significantly. As a result, the car may not pass a technical inspection. Even if the inspection is not carried out, then environmental care is the task of every inhabitant of the planet, and not of individual organizations.

How are mufflers made?

In order for the new product to cope with its primary task and not create excessive backflow (exhaust gas resistance, due to which the engine will have to spend part of the torque to overcome this pressure), manufacturers calculate what the backpressure will be in a particular case. Based on this, it is determined for which power units the installation of such a silencer will be less critical.

For this reason, silencers for different car models may have different sizes and weights (this is affected by the presence of additional partitions and tubes in the silencer bulb itself). But to satisfy the needs of fans of visual tuning, analogues with a double exhaust pipe or exhaust systems with two mufflers are also being developed.

The flasks themselves are made from different grades of steel by welding. The seams are treated with anti-corrosion and refractory agents to prevent rust and muffler burnout. There are more expensive options that are made of stainless steel.

How to choose a silencer

Please note that not every muffler can be installed on your car. The problem is that each element of the exhaust system is created for the parameters of the motor - its volume and power.

If an unsuitable part is installed on the machine, excessive resistance may be created in the exhaust system to exhaust the exhaust gas. Because of this, the power of the motor can significantly decrease.

Here's what to look for when choosing a new muffler:

• The volume of the can. The bigger the bank. The better the noise absorption and better gas removal.
• Quality details. If metal folds or a painted part are visible, then it is better not to buy such a muffler.
• A suitable muffler can be found on the vehicle VIN. So it’s easier to pick up the original spare part. If this is not possible, then the search should be by brand and model of car.

Separately, it is worth mentioning the opportunity to purchase used parts. In the case of silencers, this is a bad idea. It is not known in what conditions the spare part was stored. Since the main material from which they are made is steel, they are susceptible to corrosion. There is a high probability of buying an already rotten muffler, but outwardly it will not be noticeable.

Brand Tour

When buying any part (not just elements of the exhaust system), it is extremely important to choose products from well-known brands. Among the manufacturers who offer quality silencers, the following can be distinguished:

• Bosal. Belgian company that has established itself with quality products.
• Walker. The Swedish brand also sells durable and effective silencers.
• Polmostrow. The peculiarity of the Polish company is that it offers its customers a wide selection of different modifications of silencers. Often the company's products are sold at an average price.
• Asso. Italian parts are of high quality, but often they need refinement, because even the model for which they are created, the silencer may not be suitable. This complicates the repair of the exhaust system.
• Atiho. Despite the fact that the products of the Russian manufacturer do not differ in the same high quality as the European counterparts, all products are sold at an affordable price.

The process of choosing a muffler depends on the motorist himself and his financial capabilities.

How to recognize a fake

Often unscrupulous sellers sell Chinese or Turkish goods at the price of the original. Sometimes they themselves do not suspect that they are selling a fake. Here are the factors for calculating low-quality products:

• Thin metal. Such material is used to make cheap parts. Most often, such silencers are quite light and can be deformed.
• Packaging. If there is no manufacturer’s marking on the muffler (stampings, notches, logos with holograms, etc.), then this is most likely a fake.
• The volume of the can. The original part is always more than a fake, because in the second case, the manufacturer does not pursue quality in order to get more benefits, saving on material.
• Cost. The original is always more expensive. However, this should not be the only factor by which the quality of the spare part is determined. Often, buyer’s ignorance is used by unscrupulous sellers, realizing fake at the price of the original.

How to install a silencer

The installation scheme of a car muffler is quite simple. To do this, raise the car on a jack or lift. The next step is to dismantle the old part. All parts of the exhaust system are connected using special connectors - earrings (a metal ring that is inserted at the junction of the elements) and a metal clamp.

It is important that all the edges of the pipes fit snugly against each other, otherwise the exhaust gases will leak out through the hole formed. This will immediately become known when the driver starts the engine.

It is worth considering that during the operation of the exhaust system its elements become very hot. Often this leads to baking of the joints. In view of this, it is sometimes necessary to loosen the pipe during dismantling. In this case, you must be careful so as not to damage the corrugation (if any) or the exhaust pipe.

Related videos

Here is a detailed video about the operation of the car exhaust system:

How the exhaust system and muffler work. Why is the flow of exhaust gases faster than the speed of sound

Questions and answers:

Why a muffler in cars? This part of the exhaust system provides: reduction of exhaust gas noise, damping of exhaust speed, cooling of exhaust gases and reduction of their pulsation.

Where is the muffler of the car? It is a volumetric vessel with two openings (inlet and exhaust). There are several perforated baffles and insulation inside the muffler.

How does a car muffler work? Exhaust gases enter the cavity, are reflected from the baffle, enter the pipe between the cavities (the number of chambers depends on the muffler model), and then into the exhaust pipe.