What is an intake manifold in a car device
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What is an intake manifold in a car device

For the preparation and high-quality combustion of the air-fuel mixture, as well as for the effective removal of combustion products, vehicles are equipped with an intake and exhaust system. Let's figure out why you need an intake manifold, what it is, and also the options for tuning it.

The purpose of the intake manifold

This part is designed to ensure the supply of air and VTS to the cylinders of the motor while it is running. In modern power units, additional elements are installed on this part:

  • Throttle valve (air valve);
  • Air sensor;
  • Carburetor (in carburetor modifications);
  • Injectors (in injection internal combustion engines);
  • A turbocharger whose impeller is driven by the exhaust manifold.

We offer a short video about the features of this element:

Intake manifold: frequently asked questions

Intake manifold design and construction

One of the most important factors affecting motor efficiency is the collector shape. It is presented in the form of a series of pipes connected in one branch pipe. An air filter is installed at the end of the pipe.

The number of taps at the other end depends on the number of cylinders in the motor. The intake manifold is connected to the gas distribution mechanism in the area of ​​the intake valves. One of the disadvantages of VC is the condensation of fuel on its walls. To prevent this effect of electrostatic reaction, engineers have developed a pipe shape that creates turbulence inside the line. For this reason, the inside of the pipes is deliberately left rough.

What is an intake manifold in a car device

The shape of the manifold pipes must have specific parameters. First, the tract should not have sharp corners. Because of this, the fuel will remain on the surface of the pipes, which will lead to clogging of the cavity and change the parameters of the air supply.

Second, the most common intake tract problem that engineers continue to struggle with is the Helmholtz effect. When the intake valve opens, air rushes to the cylinder. After its closure, the flow continues to move by inertia, and then abruptly returns. Because of this, a resistance pressure is created, which interferes with the movement of the next portion in the second pipe.

These two reasons are forcing car manufacturers to develop better manifolds that provide a smoother intake system.

Principle of operation

The suction manifold operates in a very simple way. When the engine starts, the air valve opens. In the process of moving the piston to the bottom dead center on the suction stroke, a vacuum is created in the cavity. As soon as the inlet valve opens, a portion of air moves at high speed into the vacated cavity.

What is an intake manifold in a car device

During the suction stage, different processes take place depending on the type of fuel system:

All modern engines are equipped with an electronic system that controls the supply of air and fuel. This makes the motor more stable. The dimensions of the pipes are matched to the parameters of the motor at the stage of manufacturing the power unit.

Manifold shape

This is a very important factor, which is given the key importance in the design of the intake system of a separate engine modification. The pipes must have a specific section, length and shape. The presence of sharp corners, as well as complex curvatures, are not allowed.

Here are some reasons why so much attention is paid to the intake manifold pipes:

  1. Fuel can settle on the walls of the intake tract;
  2. During the operation of the power unit, Helmholtz resonance may appear;
  3. For the system to function properly, natural physical processes are used, such as the pressure created by the air flow through the intake manifold.

If the fuel constantly remains on the walls of the pipes, this can subsequently cause a narrowing of the intake tract, as well as its clogging, which will negatively affect the performance of the power unit.

As for the Helmholtz resonance, this is an age-old headache for designers who design modern power units. The essence of this effect is that when the intake valve closes, a strong pressure is created, which pushes air out of the manifold. When the inlet valve is reopened, the back pressure causes the flow to collide with a counter pressure. Due to this effect, the technical characteristics of the intake system of the car are reduced, and the wear of the system parts also increases.

Intake manifold change systems

Older machines have a standard manifold. However, it has one drawback - its efficiency is achieved only at a limited engine operating mode. To expand the range, an innovative system has been developed - Variable Header Geometry. There are two modifications - the length of the path or its section is changed.

Variable length intake manifold

This modification is used in atmospheric engines. At low crankshaft speeds, the intake path should be long. This increases throttle response and torque. As soon as the revs increase, its length must be reduced in order to reveal the full potential of the car's heart.

To achieve this effect, a special valve is used, which cuts off the larger manifold sleeve from the smaller one and vice versa. The process is regulated by natural physical law. After the intake valve is closed, depending on the frequency of the oscillation of the air flow (this is influenced by the number of crankshaft revolutions), pressure is created, which drives the shut-off flap.

What is an intake manifold in a car device

This system is used only in atmospheric engines, since air is forced into turbocharged units. The process in them is regulated by the electronics of the control unit.

Each manufacturer calls this system in its own way: for BMW it is DIVA, for Ford - DSI, for Mazda - VRIS.

Variable intake manifold

As for this modification, it can be used both in atmospheric and turbocharged engines. When the cross-section of the branch pipe decreases, the air velocity increases. In an aspirated environment, this creates the effect of a turbocharger, and in forced air systems, the development makes it easier for a turbocharger.

Due to the high flow rate, the air-fuel mixture is more efficiently mixed, which leads to its high-quality combustion in the cylinders.

What is an intake manifold in a car device

Collectors of this type have an original structure. At the entrance to the cylinder there is more than one channel, but it is divided into two parts - one for each valve. One of the valves has a damper that is controlled by the car electronics using a motor (or a vacuum regulator is used instead).

At low crankshaft speeds, the BTC is fed through one hole - one valve works. This creates a zone of turbulence, which improves the mixing of fuel with air, and at the same time its high-quality combustion.

As soon as the engine speed rises, the second channel opens. This leads to an increase in the power of the unit. As in the case of variable length manifolds, the manufacturers of this system give their name. Ford indicates IMRC and CMCV, Opel - Twin Port, Toyota - VIS.

For more information on how such collectors affect motor power, see the video:

Intake manifold malfunctions

The most common faults in the intake system are:

Generally, gaskets lose their properties when the motor gets too hot or when the fastening pins are loosened.

Let's consider how some malfunctions of the intake manifold are diagnosed and how they affect the operation of the motor.

Coolant leaks

When the driver notices that the amount of antifreeze is gradually decreasing, while driving, an unpleasant smell of burning coolant is heard, and drops of fresh antifreeze constantly remain under the car, this may be a sign of a faulty intake manifold. To be more precise, not the collector itself, but a gasket installed between its pipes and the cylinder head.

On some engines, gaskets are used that also ensure the tightness of the engine cooling jacket. Such malfunctions cannot be ignored, because subsequently they will necessarily result in a serious breakdown of the unit.

Air leaks

This is another symptom of a worn intake manifold gasket. You can diagnose it as follows. The engine starts, the air filter branch pipe is blocked by about 5-10 percent. If the revolutions do not fall, it means that the manifold is sucking in air through the gasket.

What is an intake manifold in a car device

Violation of the vacuum in the engine intake system causes unstable idle speed or complete failure of the power unit to work. The only way to eliminate such a malfunction is to replace the gasket.

Less often, air leaks can occur due to the destruction of the intake manifold pipe (s). for example, it could be a crack. A similar effect occurs when a crack forms in the vacuum hose. In this case, these parts are replaced with new ones.

Even less often, air leaks can occur due to deformation of the intake manifold. This part needs to be changed. In some cases, a vacuum leak through a deformed manifold is detected by a hiss coming from under the hood while the engine is running.

Carbon deposits

Typically, such a malfunction occurs in turbocharged units. Carbon deposits can cause the engine to lose power, misfire and increase fuel consumption.

Another symptom of this malfunction is loss of traction. It depends on the degree of clogging in the intake pipes. It is eliminated by dismantling and cleaning the collector. But depending on the type of manifold, it is easier to replace it than to clean it. This is because, in some cases, the shape of the nozzles does not allow for the proper removal of carbon deposits.

Problems with the intake geometry change valves

The manifold air dampers in some cars are powered by a vacuum regulator, while in others they are electrically driven. Regardless of what type of dampers are used, the rubber elements in them deteriorate, from which the dampers cease to cope with their task.

If the damper drive is vacuum, then you can check its performance using a manual vacuum pump. If this tool is not available, then a regular syringe will do. When a vacuum drive is found to be missing, it should be replaced.

Another malfunction of the damper drive is the failure of the vacuum control solenoids (solenoid valves). In engines equipped with an intake manifold with a variable geometry, a valve may break, which regulates by changing the geometry of the tract. For example, it may deform or it may stick due to carbon build-up. In case of such a malfunction, the entire manifold must be replaced.

Intake manifold repair

During the repair of the collector, the readings of the sensor installed in it are first taken. So you can make sure that the fault is in this particular node. If the breakdown is indeed in the manifold, then it is disconnected from the motor. The procedure is performed in several stages:

What is an intake manifold in a car device

It is worth considering that some faults cannot be repaired. Valves and dampers belong to this category. If they are broken or work intermittently, then you just need to replace them. If the sensor breaks down, dismantling of the assembly is not required. In this case, the ECU will receive incorrect readings, which will lead to incorrect preparation of the BTC and negatively affect the performance of the motor. Diagnostics are able to recognize this malfunction.

During repairs, due attention must be paid to the joint seals. A torn gasket will cause pressure leaks. Once the manifold has been removed, the inside of the manifold must be cleaned and flushed.

Collector tuning

By changing the design of the intake manifold, it is possible to improve the technical characteristics of the power unit. Typically, the collector is tuned for two reasons:

  1. Eliminate the negative consequences caused by the shape and length of the pipes;
  2. To modify the interior, which will improve the flow of the air / fuel mixture into the cylinders.

If the manifold has an asymmetrical shape, then the flow of air or air-fuel mixture will be unevenly distributed over the cylinders. Most of the volume will be directed to the first cylinder, and to each subsequent one - the smaller one.

But symmetrical collectors also have their drawbacks. In this design, a larger volume enters the central cylinders, and a smaller one into the outer ones. Since the air-fuel mixture is different in different cylinders, the cylinders of the power unit begin to work unevenly. this causes the motor to lose its power.

In the process of tuning, the standard manifold is changed to a system with a multi-throttle intake. In this design, each cylinder has an individual throttle valve. Thanks to this, all air flows entering the motor are independent of each other.

If there is no money for such a modernization, you can do it yourself with practically no material investment. Typically, standard manifolds have internal flaws in the form of roughness or irregularities. They create turbulence that creates unnecessary turbulence in the path.

Because of this, the cylinders may fill up poorly or unevenly. This effect is usually not very noticeable at low speeds. But when the driver expects an instant response to pressing the gas pedal, in such engines it is unsatisfactory (it depends on the individual characteristics of the collector).

To eliminate such effects, the intake tract is sanded. Moreover, you should not bring the surface to an ideal state (mirror-like). It is enough to remove the roughness. Otherwise, fuel condensation will form on the walls inside the mirror intake tract.

And one more subtlety. When upgrading the intake manifold, one should not forget about the place of its installation on the engine. A gasket is installed in the place where the pipes are connected to the cylinder head. This element should not create a step, because of which the incoming stream will collide with an obstacle.

Conclusion + VIDEO

So, the uniformity of the operation of the power unit depends on the seemingly simple part of the engine, the intake manifold. Despite the fact that the collector does not belong to the category of mechanisms, but outwardly it is a simple part, the operation of the engine depends on the shape, length and condition of the inner walls of its pipes.

As you can see, the intake manifold is a simple part, but its malfunctions can cause a lot of concern to the car owner. But before starting to repair it, you should check all other systems with similar symptoms of malfunctions.

Here's a short video on how the shape of the intake manifold affects the performance of the powertrain:

Questions and answers:

Where is the intake manifold located? This is part of the motor attachment. In carburetor units, this element of the intake system is located between the carburetor and the cylinder head. If the car is injector, then the intake manifold simply connects the air filter module to the corresponding holes in the cylinder head. Fuel injectors, depending on the type of fuel system, will be installed either in the intake manifold pipes or directly in the cylinder head.

What is included in the intake manifold? The intake manifold consists of several pipes (their number depends on the number of cylinders in the engine) connected into one pipe. It includes a pipe from the air filter module. In some fuel systems (injection systems), fuel injectors are installed in the pipes suitable for the engine. If the car uses a carburetor or mono injection, then this element will be installed in the node where all the pipes of the intake manifold are connected.

What is an intake manifold for? In classic cars, air is supplied and mixed with fuel in the intake manifold. If the machine is equipped with direct injection, then the intake manifold serves only to supply a fresh portion of air.

How does the intake manifold work? When the engine starts, fresh air from the air filter flows through the intake manifold. This happens either due to natural thrust or due to the action of a turbine.

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