SUPERCHARGER: Definition, Application, Advantages & Disadvantages


The supercharger are compressors that are attached to the guidance system and are used to increase the pressure of the inflowing air.

This will increase the amount of air and fuel that enters each cylinder in each cycle.

This extra air and fuel produces more power in combustion and increases the net power of the engine.

The pressure rise can occur in the range of 20-250 kPa, and most engines are at the lower end of this range.

The superchargers is mechanically driven directly from the crankshaft of the engine.


These are positive displacement compressors that typically operate at speeds approximately equal to engine speed.

The power that drives the supercharger is a parasitic load on the engine output, which is one of the main drawbacks of turbochargers.

Further drawbacks are high cost, heavy weight and noise.

The great advantage of the supercharger is that it responds very quickly to changes in gas.

Due to the mechanical connection to the crankshaft, any change in speed is immediately transmitted to the compressor.

Some high performance car engines and almost all large CI engines are charged.

All 2-stroke engines with uncompressed crankcases (some form of supercharging) must be either supercharged or turbocharged.

If the first law of thermodynamics is applied to the air flowing through the compressor,

Wse = ma (hout-hin) = macp (Tout-Tin)


Wse = power required to drive the compressor

ma = Mass flow Amount of air in the engine

cp = Specific heat of air

h = Specific enthalpy

T = Temperature

This assumes that the heat transfer, kinetic energy and potential energy terms of the compressor are negligibly small.

This is true for most compressors.

The isentropic efficiency of all compressors is less than 100%, so the actual power required is above the ideal value.

For additional engine output, it is desirable that a higher input pneumatic is provided by the supercharger.

However, the supercharger also raises the intake air temperature by pressure heating as much as possible.

This is not desirable for SI engines.

If the temperature is high at the beginning of the compression stroke, all temperatures will be high for the rest of the cycle.

This often causes auto-ignition and knocking issues during combustion.

To avoid this, many compressors are equipped with an aftercooler that cools the compressed air to a lower temperature.

The aftercooler is either an air-to-air heat exchanger or an air-to-liquid heat exchanger.

The coolant can be air flowing through the engine compartment, or liquid engine coolant in more complex systems.

Some supercharger consist of two or more compressor stages, each stage followed by an aftercooler.

The CI engine compressor does not require an intercooler as there are no concerns about knocking issues.

The intercooler is expensive and occupies space in the engine room.

For these reasons, some car supercharger do not have an aftercooler.

These engines generally have a low compression ratio to avoid compression ignition and knocking issues.


Roots supercharger consists of two tabs that work with and rotate in opposite directions.

To reduce the need for lubrication, there is a small but accurate gap between the outer shell and the cone, and they are present between the two cones themselves.

This special design contributes to the best performance for low to medium pressure boost.

As a result, the thermal efficiency does not significantly affect the output.

It does not compress incoming air, so atmospheric pressure provides constant pumping capacity and can provide high output and torque at low engine speeds.

However, if the speed is too slow, air can escape from the empty space of the piston, which can reduce the efficiency of the fan.

This is not a problem at speed generally higher than 1000 rpm because air is a function of time and decreases with faster rotation.

A further construction related disadvantage is the small amount of air brought back from the intake system due to the cracked air in the free space of the robe.

The sealed, currently heated air heats the inflowing air, which is pushed into the guidance system.

Roots supercharger is not used in today’s vehicles because it generally limits vehicle emissions.

Second, they also tend to make a lot of noise from the movement of air to the gears and intake ducts.


The supercharger can therefore be used to improve the slow transient response of deceleration and deceleration engines.

The supercharger is used not only in the powertrain of hybrid vehicles, but also in improving the output and torque density of hyperextended cycle engines.


Increased horsepower: Adding a compressor to each engine is a quick way to improve performance.

No Delay: The main advantage of the compressor over the turbocharger is that there is no delay.

The compressor is driven by the crankshaft of the engine, so power is generated immediately.


There is an increasing detonation tendency to knock in SI engines.

Increased heat load.

Increased heat loss due to increased turbulence.

Increased gas pollution.

Motor cooling requirements have increased.

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