Supercharger explained; Types of superchargers

You may have heard of the term supercharger in vehicle review videos and automobile-related magazines. What is meant by a supercharger? What are the advantages and disadvantages of a supercharged engine?

Why use a supercharger in the engine?

Supercharging is the process of supplying air-fuel mixture at a pressure above atmospheric pressure to the engine. In a naturally aspirated engine, the air or air-fuel mixture entered into the engine cylinder with the help of a pressure depression created during suction stroke. In such a situation, the air or air-fuel mixture enters the cylinder at a pressure of atmospheric.


We know that, if more air enters the cylinder more fuel can be burned. In this way, the engine produces more power and torque. The superchargers and the turbochargers are used for this purpose. 

These both are force induction devices, which compress the air or air-fuel mixture and delivered it to the engine cylinder. By compressing, the volume decreases, and the density increases. In this way, more air enters the cylinder and produces more power and torque.

The turbochargers and superchargers are used for the same purpose, but they have some differences. The supercharges work using energy from the engine. Here it gets the drive from the crankshaft through a belt or chain. So it is not much efficient as a turbocharger, the turbocharger works with the help of exhaust gas.

The placement of these both is different, the turbocharger places on the path of the exhaust gases. But the supercharger places on the path of the intake air.

Types of superchargers

The supercharger is basically a compressor or an air pump. There are several types of air pumps, but out of these only three types are used as superchargers.

Centrifugal type supercharger

This looks like a turbocharger, but a turbocharger has two wheels, the compressor wheel, and the turbine wheel. But for a centrifugal supercharger has a single wheel called an impeller, which is used to compress the intake air.

Its main components are the impeller, diffuser, and volute casing. The impeller is run from the engine pulley using a belt. The air-fuel mixture enters the center part of the impeller, compresses, and then goes to the volute casing through a diffuser. from there the compressed air-fuel mixture enters the engine cylinders.

It works on the principle of centrifugal force, When the impeller rotates the air-fuel mixture also rotates, so the air-fuel mixture is thrown into the volute casing. At this time, the pressure of this mixture will increase and enter the cylinders.

Here gears are provided to increase the rpm of the impeller. That is the drive from the engine pulley is not directly connected to the impeller. A set of gears are provided in between them, which will increase the rpm of the impeller.

In some cases the planetary gears are used instead of normal gear, this will increase the rpm of the impeller far better. The diffuser is stationary, these are like a blade, which helps to increase the pressure of the air-fuel mixture and is thrown in a specific direction.

Advantages of a centrifugal supercharger

   Weight and size are low, so only need very low space to accommodate this assembly.
   High thermal efficiency.

Disadvantages of a centrifugal supercharge

   Its performance in lower rpm is poor compared to the other types, but there is no lag or delay like in turbochargers.
   It needs lubrication.

Roots-type supercharger

Its main parts are two rotors of the same shape. Each rotor has an individual shaft and these are connected to the gear, but both rotate at the same speed. When air enters it, the rotation of the rotor pushes air to the engine. It creates pressure and compresses the air-fuel mixture.

Advantages of roots-type supercharger

   It provides better performance at low rpm also.
   No need for a lubrication system.

Disadvantages of roots-type supercharger

   It is heavy and bigger in size. So it consumes a large area.
   It creates more heat compared to other types.

Twin screw-type supercharger

In a twin-srew type supercharger, the rotors are in the shape of a screw-like its name implies. The rotation of this rotor compresses the air-fuel mixture and then the charge enters the intercooler. From the intercooler, the output charge will have a high density, which helps to produce more power and torque.


Advantages of twin srew type supercharger

   It provides better performance in all rpm.
   No lubrication is needed.
   It does not create more heat.

Disadvantages of twin screw-type supercharger

   It is expensive

Superchargers improve the performance of an engine, so give us a good driving experience. Here has no lag or delay like in a turbocharger, and gets instant power delivery. But it is not much more efficient compared to a turbocharger because it is driven by engine drive. And also the high temperature and pressure reduce the reliability and life of the engine.
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