Objectives of super charging Mainly super charging is done to induct more amount of air into cylinder per unit times and hence to burn more amount of fuel to increase power output. Following are the objectives of supercharging

2. Content
 Supercharger, the engine booster.
 Objectives of super charging
 How it works???
 Working diagram of supercharger.
 Types of super chargers
Roots supercharger.
Twin-Screw Supercharger.
Centrifugal Supercharger.
 Drives used in Supercharger.
 Advantages and disadvantages of supercharging
 Conclusion.

3. Supercharger
The Engine Booster.
A supercharger is an equipment that
compresses the air being delivered to an
engine, allowing the combustion chamber to
be overfilled without enlarging the space.
The purpose of the super charging is
to increase power output of the engine. It
increases volumetric efficiency of the engine
above that of normal aspiration. Super
charging is achieved by supplying air or air-
fuel mixture at a pressure higher then the
pressure at which the engine naturally
aspirates air. Super charging is also called
boosting
A typical supercharger

4. Objectives of super charging
Mainly super charging is done to induct more amount of air into cylinder per unit
times and hence to burn more amount of fuel to increase power output. Following are the
objectives of supercharging
For a given weight and bulk of the engine, super charging increase power
output. This is important in air craft, marine and automotive engines where
weight and space are considered
To obtain better performance from the existing engine
To compensate for loss of power due to high altitudes for air craft engines

5. Principle Of Working
More fuel + More air = Bigger explosion = Greater horsepower
NOTE:
 But we cannot simply pump more fuel into the engine.
 The chemically correct mixture ±(14 : 1 :: air : fuel)±is
essential for an engine to operate perfectly.
 Thus superchargers provides more air by compressing air above
atmospheric pressure , hence providing more fuel into the charge
& would make for a more powerful explosion .
 Thus: Increased Power , Torque and Speed is achieved.

6. Working diagram of supercharger
A standard engine with the addition of a supercharger

7. Methods of supercharging
As discussed earlier, supercharging is a pressure boosting device which supplies air (in case
of diesel engine) or air-fuel mixture (in case of SI engine) to the engine cylinder at higher
pressure.
The different methods are used to run a super charger.
 Super charging of engine by compressor
 Super charging with turbine driven by engine exhaust
 Super charging arrangement in which engine, turbine and compressor are coupled
 Super charging method in which engine runs compressor and turbine develops power

8. Types of super chargers
Usually reciprocating compressor, displacement type rotary blowers,
centrifugal compressor are used to supercharger engine for various application. If
engine crank shaft drives super charger, then it is called mechanical super charger. If
the super charger is driven by a gas turbine which runs on exhaust gases from the
engine, then it is called Turbo-charger.
The main type of super charger are
ROOTS SUPERCHARGERS
TWIN-SCREW SUPERCHARGERS
CENTRIFUGAL SUPRCHRGES

9. ROOTS SUPERCHARGER
• Constructional features : It consists of two meshing lobes that are fitted on two
parallel shafts.
• Working of Roots Supercharger : As the meshing lobes spin, air trapped in the
pockets between the lobes is carried between the fill side and the discharge side
& large quantities of air move into the intake manifold and "stack up" to create
positive pressure. This pressurized air is received at the discharge side
Roots superchargers are usually large and sit on top of the engine.
They add more weight to the vehicle.

10. TWIN-SCREW SUPERCHARGERS
Constructional features: Twin-Screw Superchargers consist of two meshing lobes that resemble set
of worm gear. The two gears meshes in such away that the air pockets between them goes on decreasing
as air moves ahead.
Working of Twin Screw Superchargers: A twin-screw supercharger operates by pulling air through a
air of meshing lobes that resemble set of worm gears.
The rotors have a conical taper, which means the air pockets decrease in size as air moves from the fill
side to the discharge side .Thus a twin-screw supercharger compresses the air inside the rotor housing.
As the air pockets shrink, the air is squeezed into a smaller space.
1. Thus twin-screw superchargers are more
efficient compared to roots supercharger.
2. They cost more because the screw-type
rotors require more precision in the
manufacturing process.
3. They also make a lot of noise.
4. The compressed air exiting the discharge
outlet creates a whine or whistle that must be checked with noise suppression techniques.

11. CENTRIFUGAL SUPRCHRGES
• Constructional features: Centrifugal superchargers consist of an impeller with several
blades that rotate at a very high speed at around 50000rpm.This impeller throws the air
outside due to centrifugal force.
• Working of Centrifugal Supercharger: As the air is drawn in the hub of the impeller,
centrifugal force causes it to radiate outward. The air leaves the impeller At high speed, but
Low pressure. A diffuser converts the high-speed, low-pressure air to low-speed, high-
pressure air.
 Thus pressurize air is achieved.
1. Impeller speeds can reach ‘50,000 to 60,000RPM’.
2. They are small, light weight and attachable to the front of the engine.
3. Thus the centrifugal superchargers are the best among the above list.

12. DRIVERS USED IN SUPERCHARGERS
Drives are basically the equipments that are used to transfer power from one shaft to
another shaft. in a supercharger, drive are used to transfer part of engine power to
the supercharger
 There are several types of drives used to empower a supercharger. These drive
are used according to there requirement
Some of them are as under:
 Mechanical
 Belt(V belt, toothed belt& Flat belt).
 Gear drive.
 Chain drive.
 Exhaust gas turbine:-
 Axial turbine
 Radial turbine.
 Other:-
 Electric motor.

13. Advantages and disadvantages of supercharging
Advantages {effect on engine performance}
 Power output of the engine can be increased
 More quantity of charge can be induced into engine cylinder
 Better automization of fuel is possible
 Better mixing of air and fuel can be obtained
 Better scavenging of exhaust gases is possible
 Torque is improved for whole speed range and better torque at low speed
 Faster acceleration of the engine is possible
 The specific fuel consumption is lowered slightly
 A better mechanical efficiency and efficient combustion is possible
 In CI engines, exhaust smoke is reduced
Disadvantages
 Detonation tendency increases in SI engines
 Heat losses due to turbulence and thermal stresses are more
 The value overlap period increase upto 160 degree of crank angle
 Better lubrication is required
 Better cooling of piston and values is required
 It increase cost of the engine

14. Conclusion
 Despite their disadvantage, superchargers are still the most cost-effective way to increase
horsepower.
 Superchargers can result in power increase of 50 to 100 percent, making them great for
racing, towing heavy loads or just adding excitement to the typical driving experience.
 It is a must use component in an airplanes.
 With the use of high octane premium-grade gas, I think it is a miracle invention for speed
junkies.

15. References
 White, Graham. Allied Aircraft Piston Engines of World War II: History and
Development of Frontline Aircraft Piston Engines Produced by Great
Britain and the United States during World War II. Warrendale, Penn:
Society of Automotive Engineers, Inc.; Shrewsbury, England: Airlife
Publishing Ltd.; 1995. ISBN 1-56091-655-9, ISBN 1-85310-734-4
 Chartered Mechanical Engineer. Great Britain: Institution of Mechanical
Engineers. 1974-01-01 – via Google Books.
 Georgano, G.N. (1982). The new encyclopedia of motorcars 1885 to the
present (ed.3. ed.). New York: Dutton. p. 415. ISBN 0-525-93254-2
 Twin-screw vs. Centrifugal Supercharging Kenne Bell