The document discusses methods to increase engine power, focusing on supercharging and turbocharging techniques. Superchargers provide forced induction by compressing air into the combustion chamber, while turbochargers utilize exhaust gases for similar purposes, improving efficiency and power. It highlights the advantages and drawbacks of turbo and supercharging systems, particularly the performance characteristics of variable geometry turbochargers compared to conventional ones.

1. PANKAJ UDHAV ARVIKAR
M.TECH (AUTOMOBILE)
172100015

2. • To increase the output of any engine more fuel can be burned and make
bigger explosion in every cycle.
 One way to add power is to build a bigger engine.
> But bigger engine, which weigh more and cost more to build and
maintain are not always better
 Another way to add power is to make a normal sized engine more efficient.
> This can be accomplish by forcing more air into the combustion
chamber.
> More air means more fuel can be added and more fuel means a bigger
explosion and greater horsepower.
• This can be done with the help of turbocharger and supercharger

3.  A supercharger is an air compressor used for forced induction of an internal
combustion engine.
 The greater mass flow-rate provides more oxygen to support combustion
than would be available in a naturally aspirated engine.
 Supercharger allows more fuel to be burned and more work to be done per
cycle, increasing the power output of the engine.
 Power for the unit can come mechanically by a belt, gear, shaft, or chain
connected to the engine's crankshaft .

4.  To raise the density of the air charge, before it enters the cylinders.
 To raise engines power output for a given weight and size of the engine.
(for aircraft, marine and automotive engines).
 To compensate for the loss of power due to altitude.
 To increase the volumetric efficiency.

5. Air
Filter

6. Fig. p-v cycle of Naturally aspirated Engine Fig. p-v cycle of Supercharged Engine

7.  There are two main types of superchargers defined according to the
method of compression
i. Positive displacement (ex. Twin-screw, roots)
ii. Dynamic compressors (ex. Centrifugal)
 The former deliver a fairly constant level of pressure increase at all
engine speeds (RPM), whereas the latter deliver increasing pressure with
increasing engine speed.
 Dynamic compressors rely on accelerating the air to high speed and then
exchanging that velocity for pressure by diffusing or slowing it down.

8. Centrifugal
Axial Flow
Vane
Twin-screw
Roots

9. A supercharger can consume as much as 20 percent of an engine's
total power output.
Increase in pressure increases thermal load on engine due to increase
in the rate of heat release.
Detonation tendency increases in SI engine.
Reliability of engine decreases with increase in maximum pressure
in the cylinder.
Increase the strain on engine and gear train.

10.  A turbocharger, or turbo is a centrifugal compressor powered by a turbine that is
driven by an engine's exhaust gases.
 To improve an engine's volumetric efficiency by increasing the intake density.
 The turbine converts the engine exhaust's potential pressure energy and kinetic
velocity energy into rotational power, which is in turn used to drive the compressor.

11. The turbocharger has three main components
 A turbine, which is almost always a radial in flow turbine
1. Twin turbo
2. Twin scroll
3. Variable Geometry
 A compressor, which is almost always a centrifugal compressor
 The centre housing/hub rotating assembly

13.  More power compared to the same size naturally aspirated engine.
 Better thermal efficiency over naturally aspirated engine and super charged engine.
 Better Fuel Economy by the way of more power and torque from the same sized
engine.
 Better volumetric efficiency.
 High speed obtained.
 Better average obtained.
 Engine weight will increase.
 If there will be improper maintenance then there will be problem in turbo
such as turbo lag.
 Engine cost will increase.

14. Effect of Variable Geometry
Turbocharger (VGT) on Diesel
Engine
(ISSN: 2394-9333)

15. Constant Aspect Ratio(A/R ratio) :-
Turbocharger Lag
• It is also known as Turbocharger Transient Response Time.
• It is defined as the time taken by the engine to change the power output in response
to the throttle change.
• Depends upon the inertia of the rotating parts and the efficient projection of exhaust
gases onto the turbine vanes
smallest c.s.a.of intake passage of turbine housing
distance from central turbine wheel to centroid of area.
A/R ratio =

16. • It has a mechanism by which the inlet area can be varied to obtain the required
A/R ratio for a given flow rate.
• By reducing the A/R ratio at low engine speed (when exhaust flow is low), and
then gradually increasing, as engine speed increases (when exhaust flow is high).

17.  In this study applying the VGT turbo and conventional turbo to the high speed direct
injection (HSDI) diesel engine and comparing the performance characteristics of the
both cases.
 Vehicle used is international class VI 4700 series delivery truck.
 The engine simulation used is the V8 DI 7.3 L diesel engine.
The specifications of the engine are as follows:The vehicle and driveline specification as follow:

18. Experimental procedure
• For comparison study of VGT and conventional turbocharger, engine system is run at
the full load.
• Case A :- Engine is enhanced by VGT
• Case B :- Engine is attached with Conventional Turbocharger
• In the both the cases the engine is accelerated between the 0-60 mph.
• The fuel injection time is kept same for the both cases.
• At initially the engine is start at the full load with breaks applied and after the 5 seconds
breaks are released to achieve the maximum demand up to the 60 mph speed of the
vehicle and the engine and vehicle parameters are measured.
• The parameters measured during each case are engine speed (rpm), vehicle speed (rpm),
boost (bar), fuel injected (g/cycle) and F/A (fuel/air) equivalence ratio Vs. time(s)

19. Test Results

20.  The turbocharger lag can be eliminated by using VG turbocharger because of higher boosting pressure at
low speed.
 There is a cost penalty in choosing a VGT above a conventional turbocharger, but it comes with many
performance improvements. The technology discussed can provide improved fuel efficiency, transient
response, emissions and torque characteristics.
 The boost pressure is more at low speed also because of using VG turbochargers.
 The take off speed of VG turbocharged engine vehicle is faster than conventional turbocharged.
 VG systems will continue to play an important role in future energy recovery and boosting applications
for internal combustion engines.
 Cost-benefit considerations will dictate many of the choices embedded in the development of such
systems.
Learnings and Conclusions

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