Forced inductionTURBOCHARGERS VS. SUPERCHARGERS

BY

G. JAYAKRISHNASEKHAR REDDY

Abstract This seminar gives the overview of forced induction processes for the engine and their advantages and disadvantages. The forced induction is a process in combustion engines by which we can increase the efficiency of an engine. The main purpose of forced induction process is to increase the volumetric efficiency, reusing the waste hot gases, increasing the engine horse power, reducing the emissions from the engine by maintaining the sufficient combustion rate. In this seminar, we specifically discuss two important forced induction processes, one is turbocharging and supercharging and which is best one for the engines that we are using in real world. What is the solution if two process aren’t fit separately?

FORCED INDUCTION What is forced induction?

Process of delivering the compressed air.

Why forced induction?

Increase the engine power efficiency, total compression ratio.

Maximum energy per unit of fuel.

General forced induction process

1. Turbocharger2. Supercharger

3. Nitrous oxide (NO2 )

TURBOCHARGER◦ What is a turbocharger? Turbine driven forced induction device◦ Why turbocharging? Increase performance of an engine, fuel

efficiency.◦ How it operates? Turbine drive the compressed air into the

engine◦ Turbo lag◦ Boost threshold

Types of superchargers1. Twin turbochargers2. Twin scroll turbochargers3. Variable geometry turbochargers.

Twin turbochargers◦ Two separate turbochargers◦ Parallel or series◦ Parallel – one half of engine’s exhaust◦ Series – one runs on low speed and other on

high speed

Twin scroll turbochargers1. Two exhaust nozzles2. Two inlet nozzles3. Physically separate the channels for the

cylinders

Variable geometry turbochargers

1. Use movable vanes2. Adjusted by actuator3. Maintains exhaust velocity and back pressure

SUPERCHARGERS◦ What is a supercharger?

Air compressor that increases the engine’s performance

◦ Why supercharging an engine? To produce the boost when engine operates

◦ How it operates?

Types

1. Positive displacement type

2. Dynamic compressor type

Positive displacement type

Roots type supercharger1. Meshing lobes2. Air trapped between fill side and discharge

side3. Large and sit on top of the engine4. External compression type5. Add weight6. Least efficient superchargers7. Back flow

Twin screw superchargers1. Lysholm – style blowers2. Use meshing lobes like worm gears3. Compress the air inside the root housing4. More efficient and more cost5. More noise6. Internal compression type7. No back flow

Dynamic compressor type

Centrifugal supercharger1. Powers an impeller2. Resembles turbocharger3. Uses impeller 4. Convert the high speed, low pressure air to

low speed, high pressure air5. Most efficient and most commonly used forced

induction systems

Turbochargers vs. Superchargers

Head to head comparisonTURBOCHARGERS

1. Cost is nearly same as superchargers

2. Lag

3. Uses waste gases to run

4. It is very hot in condition

5. Surge may deliver to the engine

6. Back pressure

7. Less noise

8. Less reliable

9. Difficult to install and tune

10. High power output and runs even at high rpm

SUPERCHARGERS1. Cost is nearly same as turbochargers

2. No lag

3. Uses crank power to run

4. Fresh air discharge

5. No surge

6. No back pressure

7. More noise

8. More reliable

9. Easy to install and tune

10. Less power output when compared to turbos

conclusion While the supercharger is generally considered to be a method of forced induction for most street and race vehicles, the turbo will always have its place in a more specialized market. Superchargers generally provide a much broader powerband that most drivers looking for with no “turbo lag”. In addition, they are much easier to install and tune.

Another Solution

Twincharger◦ Uses both turbocharger and supercharger◦ Desirable for small displacement motors with

high rpm◦ Roots charger and turbocharger in series◦ Electromagnetic clutch◦ Low rev – supercharger ◦ Later turbo join◦ Then both contribute◦ High rev – supercharger disengages◦ High cost