Turbocharger has been an indispensable part of modern heavy truck diesel engine. It greatly improves the power and torque of the engine under the same displacement, improves the fuel economy, and meets people’s demand for high horsepower and high torque diesel engine. Moreover, due to the reduction of fuel consumption per unit power, it is easier to meet the emission regulations than naturally aspirated engine, It can be said to kill many birds with one stone.

So the question is, how many parts does the turbocharger consist of? What is its principle? How does it increase engine power? Let’s break it down one by one.

Composition of alt4518523876115456 turbocharger_ Principle of turbocharger

Composition of turbocharger

The turbocharger is mainly composed of several parts: shell (including turbine shell and compressor impeller shell), rotor (including turbine and impeller). The exhaust gas drives the turbine to generate power, and the turbine drives the impeller to compress air), intermediate (there are lubricating oil passages and bearings inside, which are responsible for heat dissipation and reducing friction), sealing ring (responsible for sealing), pressure relief valve (at the moment of oil collection, because the engine does not need to generate so much power, Therefore, there is no need for a large amount of air to enter the cylinder. At this time, the supercharger still generates pressure due to inertial rotation. At this time, the pressure relief valve is required to release the pressure to prevent parts from being damaged due to excessive pressure).

In real operation, because the compressed air of the impeller will increase the air temperature, and the excessive inlet temperature will reduce the efficiency of the engine, the auxiliary work of the intercooler for cooling air is also required.

Principle of turbocharger

The exhaust gas enters the turbine housing through the exhaust manifold to drive the turbine to rotate. Because the turbine and the impeller are coaxial, the impeller in the housing on the other side also rotates with the turbine. The impeller compresses the air and sends the high-density compressed air into the combustion chamber to participate in combustion.

The whole process does not take power from the engine, and is driven by the exhaust gas generated by the engine, which hardly causes the engine to produce additional load.

How does turbocharging increase engine power

The engine needs fuel and air for combustion. The turbocharger increases the intake density. Under the same volume, the increase of air quality makes more oxygen, so the combustion will be more sufficient, which improves the power and saves fuel to a certain extent.

However, this part of the efficiency improvement is not the main reason for the significant increase in the power of turbocharged engine compared with naturally aspirated engine under the same displacement.

Turbocharging is mainly to significantly increase the intake volume and break through the limitation of intake volume of naturally aspirated engine. Therefore, more fuel can be introduced to participate in combustion under the same displacement. Only when more fuel is ignited per unit time can the power be greatly improved.

Therefore, even if turbocharging improves fuel utilization, the significant power increase it brings also requires more fuel participation.

It can be popularly understood that the turbocharged engine has lower fuel consumption under the same power, rather than lower fuel consumption under the same displacement.


The development of turbocharged diesel engine has been very mature. Recalling the shortcomings of turbocharging technology when it was first applied, such as reliability, turbine hysteresis, poor working environment, short service life and so on, have been basically solved.

The progress of turbocharging technology has also led to the revolution of engine technology. We hope that more new technologies will be applied to traditional engines in the future. Today, with the strong rise of new energy, how far can traditional engines go? Let’s wait and see.

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