What is a resonator of the exhaust system

What is a resonator?

The main purpose of a resonator is to dampen the sound vibrations of roaring exhaust gases bursting out of the combustion chamber. The size, shape and design of the resonator directly affect how loud the engine will be. If this part fails, the entire exhaust system is disrupted. The car becomes noisy, the smell of exhaust penetrates into the cabin. The history of the resonator in the exhaust system

The first soundboard appeared in cars in the early 20th century. Reducing noise levels was the first task the developers had to solve, as soon after the appearance of serial cars, there was dissatisfaction with their excessively noisy operation by pedestrians. With this part began the creation of a full-fledged exhaust system, which can be seen in modern cars.

How the resonator works

Exhaust gases are produced in the combustion chamber and exhausted from the cylinder through the exhaust valve. They then travel at high speed through the exhaust manifold and intake pipe. The temperature of the gas mixture is about 650 degrees Celsius, so the parts of the exhaust system are subjected to serious thermal stress. The hardest part is designing a resonator for a sports car. On the one hand, it has to let the flow of gases through without creating obstacles. On the other hand, it has to reduce the noise level.

The gas flow then enters the catalytic converter, and then the resonator, which is a cavity with one or more chambers. A tube with small openings passes through the chambers, through which the separated gas flow passes. The passage through the tube contributes to the mutual absorption of sound waves.

Types of resonators

More sophisticated modern resonators may have a shell with thermal insulation material between the layers. Such parts not only absorb noise, but also allow you to protect the body from heating.

Combined resonators, which consist of two parts, are increasingly common in the automotive industry. The first part of the part is based on a classic design with a tube and internal bulkheads, while the second part is filled with noise-absorbing material (usually basalt fiber). Such combined resonators are more efficient than conventional resonators.

Resonator Operation and Troubleshooting

The longest-lasting resonator is a double-body resonator. The material must be impervious to corrosion. As a rule, inexpensive mufflers for consumer market cars are made of aluminized steel, that is ordinary steel coated with a thin layer of aluminum, which protects the surface from corrosion. The volume of the resonator also plays an important role. It is a measure of the efficiency of the resonator. If the volume is insufficient, then during a sharp pressure on the accelerator pedal the noises will be significantly amplified, and the part itself can begin to vibrate. Buying an alluminized steel resonator, you should remember that the low price of the product is obtained by reducing the durability. The best resonators are made of stainless steel

As any part of the exhaust system, the resonator is exposed to the harmful effects of aggressive factors: working in a gas environment, high temperatures. Because of this, the service life of the exhaust system parts is very short. Signs of failure may be an increase in noise, the smell of exhaust gases in the car, the presence of jets of smoke under the bottom. In this case, it should be replaced.

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The resonator in motorsport

Due to its simplicity and low weight, the resonator finds application in motorsport, but for this purpose, the part is often subjected to significant modifications. As a rule, resonators are installed in sports cars that have a more complex type of chamber, which provides sound absorption and has minimal resistance, that is, it does not increase the back pressure in the exhaust system. Sport mufflers are usually made of stainless steel, as it has a smoother surface (creating a minimum of eddies in the system), and parts made of it work better in extreme temperature conditions.

Muffler resonator in an exhaust system

The muffler resonator is a part of the exhaust system, whose tasks include damping low frequency sounds arising from engine operation. It will be useful for every motorist to know where the resonator is, and what possible problems it will have to face during its service life. Breakdown of the resonator of the exhaust pipe is not critical, but can cause a lot of inconvenience not only to the driver, but also to the people around him. On how to eliminate the problems that have arisen, how to dismantle and install the unit, as well as how to make the resonator with your own hands – about all this we will talk in this material.


Purpose of the resonator

To begin with, let’s understand what the resonator is needed for . As mentioned above, it is part of the exhaust system of the car engine. Its main function is to dampen the low frequency sounds that arise when the gases are exhausted and enter the gas exhaust system. There are two reasons why noises occur in it:

  • Sound from the expansion of the gases;
  • Noise from the vibration of the exhaust system components.

where is the resonator

Together with the muffler, the tasks of the automotive resonator include reducing the velocity of the exhaust gas movement. This is made possible by a physical law, according to which the gases, which move quickly in a narrow pipe, lose their speed, and consequently their energy, when they enter a large volume. In the exhaust system, the resonator stands before the main silencer, being, in fact, the first link in the chain of silencing of sounds in the exhaust system. That is, its main tasks are preliminary noise reduction and balancing the pulsation of the exhaust gas flow.

Some car owners call it the “middle muffler” (because of its physical location approximately in the middle of the car bottom) or the “second muffler”. However, this is incorrect, because the exhaust system resonator and muffler have different principles of operation.

The resonator in a car’s exhaust system also has the function of freeing the engine’s exhaust gases and creating a uniform pressure in it. This ensures that there is minimal resistance to the movement of the exhaust gases and allows almost all of the useful power of the engine to be utilized.

Since the resonator still draws a portion of the power of 10. 15%, the so-called straight-through mufflers are used in sports cars and no resonators are installed.

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Device of the resonator

Structurally, the resonator consists of a perforated (drilled along its entire length within the device) tube placed in a metal housing. There is also a choke hole in the design, designed to increase the efficiency of damping of wave oscillations in the tube. The internal cavity of the resonator is divided into two or more unequal parts by baffles located in a transverse plane to the tube. Also included in the design of more modern exhaust resonators is a thermal and/or acoustic insulation (often the same material) located under the body and designed to reduce its temperature and/or the sounds emanating from the device.

Internal structure of the resonator

The internal cavities have an unequal volume in order to allow the flow of exhaust gases to periodically contract and expand, which in turn gives equalization of their uneven pulsation. That is, each chamber has its own resonance frequency. In addition, they have a slight offset relative to the axis of the body. This is necessary to achieve a change in the direction of the exhaust flow. And the internal perforation on the tube is needed to dampen the large amplitude of sound waves that the gases produce.

The efficiency of the resonator is affected by the following factors:

  • The degree of its wear, tightness;
  • fouling level (the cleaner, the more effective);
  • diameter (the larger the diameter of the device, the higher its efficiency).

Malfunctions of the resonator

Like any part, the car resonator periodically fails. After all, it passes through itself exhaust gases having a temperature of several hundred degrees Celsius. In combination with aggressive chemical elements, contained in the outgoing gas mixture, it leads to gradual burnout of metal parts of the system.

The main signs of resonator failure are:

  • Deterioration of the muffler and exhaust system . This can be seen in the increased sound coming from the exhaust pipe, especially the low frequency sounds (roar).
  • The emergence of exhaust fumes from underneath the machine. This is a clear indication that the resonator or other parts of the exhaust system are leaking.
  • The presence of a rattling metallic sound from the resonator. It appears due to the fact that one (or more) of the internal components of the device burns through. Usually in such cases, it “hangs” or comes off and rattles in one of the chambers.
  • Significant drop in engine power . Due to the malfunction that has occurred, the capacity of the resonator drops significantly, so it dampens the uneven pulsations of exhaust gases worse or not at all. And this gives feedback on deterioration of power unit operation.

If you encounter one or more of the above signs of a malfunctioning resonator, you need to have it inspected as soon as possible.

How to check the catalytic converter?

The condition of the catalytic converter determines the power of the engine. If there are characteristic symptoms of a breakdown, you should definitely check it. It is possible to do it for light (by disassembling) and for back pressure or CO

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VAZ 2110 Resonator Replacement

Repair of the exhaust system or replacement of the muffler on the VAZ 2110 most often consists of replacing the resonator, because to solve the problem of burning through the welding it is not possible for a long time. The main task is to quickly remove the resonator More

Resonator inspection

When identifying the above problems, every motorist should know how to check the resonator. This will not only normalize the operation of the engine and exhaust system, but also increase the comfort of using the car, including for those around you.

To check it, you will need an inspection pit (if it is not available, you can lift the car with a jack). Diagnosis is made by visual inspection. In the process, you must carefully inspect the integrity of both the device itself and the pipes connected to it (especially at their joints).

Always be careful and observe safety rules when working in the inspection pit and when lifting the machine on the jack.

A clear sign of malfunction is the formation of condensation in the cooling resonator, after which it begins to drip onto the ground. This means that its housing has lost its tightness and should be repaired, or better yet, replaced. You can check the presence of condensate after some time, when you have stopped the engine (to let the resonator housing cool down). Pay attention! Some motorists during independent manufacturing of resonators specially drill a hole in its case for moisture drainage. Therefore, if you purchased a car with a similar resonator, this method of checking will not suit you.

You can also determine the integrity of the resonator body by the presence of exhaust gases coming out of it. This also indicates a leak and the need to replace it. This fact can be checked with the car engine running by looking under the bottom. To be sure you can ask your helper to “accelerate” at the same time, so that more exhaust gases pass through the system. Appearance of smoke from underneath the car while driving or parking with the engine on is also suspicious for depressurization.

Practice shows that it is better not to repair the resonator, but to replace it. It is especially relevant for cars with significant mileage (more than 100 thousand kilometers).

Types of car resonators

When choosing a resonator of the exhaust system, it is necessary to know what they are, and of what materials they are made. Currently popular car resonators are made of aluminized steel and stainless steel. The first ones have a low price, but a short service life. Their body is made of thin steel, coated with aluminum on top to prevent corrosion. However, this anti-corrosion composition is not durable. Therefore, we do not recommend you to buy an exhaust resonator made of aluminized steel. It is better to buy a car resonator made of stainless steel. This material has a smoother surface (that is, it creates a minimum of whirls in the system), and it is also more stable when working in conditions of extreme temperatures.

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Resonator with your own hands

Before you design and assemble a resonator of your own design, you need to understand one simple thing. The thicker the material from which the exhaust system (including the resonator) is made, the more effective will be the fight against vibrations and arising noises. This is the reason why the exhaust manifold, which first receives the gases from the cylinder head, has such an impressive weight.

Components of the exhaust system of foreign cars have more mass than those of domestic cars. Accordingly, they are quieter and more comfortable.

However, when choosing a material you should not overdo it and choose too massive blanks. Otherwise, the mass of the resonator will be significant, and this will affect the dynamic characteristics of the car, and the load on its running gear.

There are a number of reasons why car owners make their own exhaust resonators. One of them is to reduce the noise that the standard factory muffler makes. This is usually done by installing an additional resonator in the exhaust system. The second reason is the manufacture and installation of a straight-through car resonator . Its features are as follows:

  • reduction of engine power loss (actually insignificant, amounts to about 5. 10%);
  • change of a sound background of work of the engine and exhaust system (for fans of low sound).

To make a straight-through resonator you will need:

  • a set of locksmith’s tools;
  • welding machine (it is desirable to use modern semi-automatic or inverter);
  • angle grinder with a set of cutting and grinding disks.

Design of the resonator will vary depending on the materials used and the imagination of the car owner. We offer you one of the options for independent manufacturing of direct-flow car resonator:

  • Prepare in advance a tube, which will be the internal basis of the resonator. It should be the same or slightly larger diameter than the factory one. Make sure that it can be easily welded to the existing system in the future, so do not choose too large a diameter (provided it is not possible to attach the pipe by means of a flange).
  • Next, you need to drill holes in this pipe, similar to the stock resonator.
  • After that you need to find a tube of a slightly larger diameter (about 3. 5 cm), which will serve as the outer casing. Its length should be less (depending on the design, on average 5. 10 cm on each side).
  • Make stopping plugs necessary to seal the body from the ends. For this purpose, sheet metal is used, where the outer diameters of the large and small pipes are drawn. After that the blanks are cut out and machined with a grinder.
  • Pipe with a large diameter put on a pipe with a smaller diameter, and the cavity between them stuffed with glass wool (or better modern mineral wool with good heat and sound insulation characteristics).
  • Then it is necessary to weld on the ends of the edges of the pipe with a large diameter pre-made stubs.
  • After the welding work, the seams should be cleaned with an angle grinder. After that, it is worth painting them.
  • The last step is to weld a new resonator into the exhaust system of the car. After the work, also clean the welding seams.
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Resonator with your own hands

The above algorithm is an approximate . There is a large variety of options for homemade resonators. In some cases, they are simply thrown out of the system, installing a piece of pipe instead. However, we do not advise you to do so, because you will not get a significant addition to the power of the car, but the additional roar of the exhaust pipe is guaranteed!

Additional problems

After installing a self-made resonator, the car owner will certainly face a number of problems that must be solved. First of all, it is about increasing the weight of the gas exhaust system, and therefore the car as a whole. This is relevant if you have used heavy metal elements for the construction of the resonator. Therefore, there may be a situation where you need to replace the brackets and/or shock absorbers. That is, to strengthen them. Otherwise, the car body will “sag”, and the chassis will experience additional load.

In addition, replacement of the resonator entails a change in the ratio of the air entering the engine and the amount of exhaust gases. Therefore, it is necessary to find out by experience which optimal settings to choose and make appropriate adjustments in the fuel supply and air filtration.

Removing and installing the resonator

Many motorists are interested in the natural question – how to remove the resonator ? The answer to this question will differ depending on the brand of the car. But in general, the algorithm is not complicated and will be approximately as follows:

  • It is necessary to disconnect the resonator pipes in the places where they connect to the exhaust system (at the front, on the side of the engine or catalytic converter, and at the rear, on the side of the muffler);
  • Remove the soundboard from its hangers, with which it is attached to the underside of the vehicle;
  • dismantle the resonator with its pipes.

How to replace the resonator of Renault Logan

Installation of the new device takes place in reverse order. When removing the resonator, it is important not to damage the o-rings that connect its spigots with the rest of the exhaust system.

As an example we present you two video instructions showing resonator replacement for popular Renault Logan and front-drive VAZ 2110, VAZ 2111, VAZ 2112, VAZ 2114, VAZ 2115, Kalina, Priora and Granta cars.

At last .

Partial or complete failure of the resonator of the car exhaust system is not a critical breakdown. To diagnose the breakdown of the resonator is not difficult even for an inexperienced car owner. This is indicated by loss of power, distribution of exhaust gases under the bottom and/or into the passenger compartment, increase in the sound background when the engine is running. However, we do recommend you not to delay with the repair, as driving with a burned out resonator can lead to failure of other elements of the car’s exhaust system.

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