OBJECTIVES
After studying Chapter 7, the reader should be able to:
1. Prepare for ASE Engine Performance (A8)
certification test content area “C” (Fuel, Air
Induction, and Exhaust Systems Diagnosis and
Repair).
2. Explain the difference between a turbocharger
and a supercharger.
3. Describe how the boost levels are controlled.
4. Discuss maintenance procedures for
turbochargers and superchargers.
Automotive Fuel and Emissions Control Systems, 2/e
By James D. Halderman and Jim Linder
© 2009 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
AIRFLOW REQUIREMENTS
• Engineers calculate engine airflow requirements
using these three factors:
– Engine displacement
– Engine revolutions per minute (RPM)
– Volumetric efficiency
Automotive Fuel and Emissions Control Systems, 2/e
By James D. Halderman and Jim Linder
© 2009 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
AIRFLOW REQUIREMENTS
Volumetric Efficiency
• Volumetric efficiency is a
comparison of the actual
volume of air–fuel mixture
drawn into an engine to the
theoretical maximum
volume that could be drawn
in.
• Volumetric efficiency is
expressed as a percentage,
and changes with engine
speed.
FIGURE 7-1 A supercharger on a Ford V-8.
Automotive Fuel and Emissions Control Systems, 2/e
By James D. Halderman and Jim Linder
© 2009 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
AIRFLOW REQUIREMENTS
Volumetric Efficiency
FIGURE 7-2 A turbocharger on a Toyota engine.
Automotive Fuel and Emissions Control Systems, 2/e
By James D. Halderman and Jim Linder
© 2009 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
AIRFLOW REQUIREMENTS
Engine Compression
• Higher compression increases the thermal
efficiency of the engine because it raises
compression temperatures, resulting in hotter, more
complete combustion.
– However, a higher compression can cause an increase in
NOX emissions and would require the use of high-octane
gasoline with effective antiknock additives.
Automotive Fuel and Emissions Control Systems, 2/e
By James D. Halderman and Jim Linder
© 2009 Pearson Higher Education, Inc.
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SUPERCHARGING PRINCIPLES
• The amount of force an air–
fuel charge produces when
it is ignited is largely a
function of the charge
density.
• Density is the mass of a
substance in a given
amount of space.
FIGURE 7-3 The more air and fuel that can
be packed in a cylinder, the greater the
density of the air–fuel charge.
Automotive Fuel and Emissions Control Systems, 2/e
By James D. Halderman and Jim Linder
© 2009 Pearson Higher Education, Inc.
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SUPERCHARGING PRINCIPLES
FIGURE 7-4 Atmospheric pressure decreases with increases in altitude.
Automotive Fuel and Emissions Control Systems, 2/e
By James D. Halderman and Jim Linder
© 2009 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
SUPERCHARGERS
• A supercharger is an engine-driven air pump that
supplies more than the normal amount of air into
the intake manifold and boosts engine torque and
power.
• A supercharger provides an instantaneous increase
in power without the delay or lag often associated
with turbochargers.
– However, a supercharger, because it is driven by the
engine, does require horsepower to operate and is not as
efficient as a turbocharger.
Automotive Fuel and Emissions Control Systems, 2/e
By James D. Halderman and Jim Linder
© 2009 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
SUPERCHARGERS
• Roots-type supercharger.
• Centrifugal supercharger.
FIGURE 7-5 A roots-type
supercharger uses two lobes to
force the air around the outside
of the housing and forces it into
the intake manifold.
Automotive Fuel and Emissions Control Systems, 2/e
By James D. Halderman and Jim Linder
© 2009 Pearson Higher Education, Inc.
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SUPERCHARGERS
Supercharger Boost Control
• Many factory-installed superchargers are equipped with a
bypass valve that allows intake air to flow directly into the
intake manifold bypassing the supercharger.
• The computer controls the bypass valve actuator.
FIGURE 7-6 The
bypass actuator
opens the bypass
valve to control boost
pressure.
Automotive Fuel and Emissions Control Systems, 2/e
By James D. Halderman and Jim Linder
© 2009 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
SUPERCHARGERS
Supercharger Service
• Superchargers are usually lubricated with synthetic
engine oil inside the unit.
• This oil level should be checked and replaced as
specified by the vehicle or supercharger
manufacturer.
• The drive belt should also be inspected and
replaced as necessary.
Automotive Fuel and Emissions Control Systems, 2/e
By James D. Halderman and Jim Linder
© 2009 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
TURBOCHARGERS
• By connecting a centrifugal
supercharger to a turbine
drive wheel and installing it
in the exhaust path, the lost
engine horsepower is
regained to perform other
work and the combustion
heat energy lost in the
engine exhaust (as much
as 40% to 50%) can be
harnessed to do useful
work.
• This is the concept of a
turbocharger.
Automotive Fuel and Emissions Control Systems, 2/e
By James D. Halderman and Jim Linder
FIGURE 7-7 A turbocharger uses some of
the heat energy that would normally be
wasted.
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TURBOCHARGERS
FIGURE 7-8 A turbine wheel is turned by the expanding exhaust gases.
Automotive Fuel and Emissions Control Systems, 2/e
By James D. Halderman and Jim Linder
© 2009 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
TURBOCHARGERS
Turbocharger Design and Operation
• A turbocharger consists of
two chambers connected
by a center housing.
• The two chambers contain
a turbine wheel and a
compressor wheel
connected by a shaft which
passes through the center
housing.
FIGURE 7-9 The exhaust drives the
turbine wheel on the left, which is
connected to the impeller wheel on the
right through a shaft. The bushings that
support the shaft are lubricated with engine
oil under pressure.
Automotive Fuel and Emissions Control Systems, 2/e
By James D. Halderman and Jim Linder
© 2009 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
TURBOCHARGERS
Turbocharger Size and Response Time
• Turbocharger response time is directly related to the
size of the turbine and compressor wheels.
• Small wheels accelerate rapidly; large wheels
accelerate slowly.
• While small wheels would seem to have an
advantage over larger ones, they may not have
enough airflow capacity for an engine.
• To minimize turbo lag, the intake and exhaust
breathing capacities of an engine must be matched
to the exhaust and intake airflow capabilities of the
turbocharger.
Automotive Fuel and Emissions Control Systems, 2/e
By James D. Halderman and Jim Linder
© 2009 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
BOOST CONTROL
• Both supercharged and turbocharged systems are
designed to provide a pressure greater than
atmospheric pressure in the intake manifold.
• This increased pressure forces additional amounts
of air into the combustion chamber over what would
normally be forced in by atmospheric pressure.
• This increased charge increases engine power.
• The amount of “boost” (or pressure in the intake
manifold) is measured in pounds per square inch
(PSI), in inches of mercury (in. Hg), in bars, or in
atmospheres.
Automotive Fuel and Emissions Control Systems, 2/e
By James D. Halderman and Jim Linder
© 2009 Pearson Higher Education, Inc.
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BOOST CONTROL
FIGURE 7-10 The unit on top of this Subaru that looks like a radiator is the
intercooler, which cools the air after it has been compressed by the turbocharger.
Automotive Fuel and Emissions Control Systems, 2/e
By James D. Halderman and Jim Linder
© 2009 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
BOOST CONTROL
Wastegate
• A turbocharger uses exhaust gases to increase boost, which
causes the engine to make more exhaust gases, which in
turn increases the boost from the turbocharger.
• To prevent overboost and severe engine damage, most
turbocharger systems use a wastegate.
• A wastegate is a valve similar to a door that can open and
close.
• The wastegate is a bypass valve at the exhaust inlet to the
turbine.
• It allows all of the exhaust into the turbine, or it can route part
of the exhaust past the turbine to the exhaust system.
Automotive Fuel and Emissions Control Systems, 2/e
By James D. Halderman and Jim Linder
© 2009 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
BOOST CONTROL
Wastegate
FIGURE 7-11 A wastegate
is used on the firstgeneration Duramax diesel
to control maximum boost
pressure.
Automotive Fuel and Emissions Control Systems, 2/e
By James D. Halderman and Jim Linder
© 2009 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
BOOST CONTROL
Relief Valves
• A relief valve vents pressurized air from the
connecting pipe between the outlet of the
turbocharger and the throttle whenever the throttle
is closed during boost, such as during shifts.
• There are two basic types of relief valves:
– Compressor bypass valve or CBV.
– Blow-off valve or BOV.
Automotive Fuel and Emissions Control Systems, 2/e
By James D. Halderman and Jim Linder
© 2009 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
BOOST CONTROL
Relief Valves
FIGURE 7-12 A blow-off valve
is used in some turbocharged
systems to relieve boost
pressure during deceleration.
Automotive Fuel and Emissions Control Systems, 2/e
By James D. Halderman and Jim Linder
© 2009 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
IF ONE IS GOOD, TWO ARE BETTER
FIGURE 7-13 A dual turbocharger system installed
on a small-block Chevrolet V-8 engine.
Automotive Fuel and Emissions Control Systems, 2/e
By James D. Halderman and Jim Linder
© 2009 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
TURBOCHARGER FAILURES
• When turbochargers fail to function correctly, a drop
in power is noticed.
• To restore proper operation, the turbocharger must
be rebuilt, repaired, or replaced.
• It is not possible to simply remove the turbocharger,
seal any openings, and still maintain decent
driveability.
Automotive Fuel and Emissions Control Systems, 2/e
By James D. Halderman and Jim Linder
© 2009 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
SUMMARY
1. Volumetric efficiency is a comparison of the actual
volume of air–fuel mixture drawn into the engine
to the theoretical maximum volume that can be
drawn into the cylinder.
2. A supercharger operates from the engine by a
drive belt and, while it does consume some
engine power, it forces a greater amount of air into
the cylinders for even more power.
3. A turbocharger uses the normally wasted heat
energy of the exhaust to turn an impeller at high
speed. The impeller is linked to a turbine wheel on
the same shaft and is used to force air into the
engine.
Automotive Fuel and Emissions Control Systems, 2/e
By James D. Halderman and Jim Linder
© 2009 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
SUMMARY
4. There are two types of superchargers: roots-type
and centrifugal.
5. A bypass valve is used to control the boost
pressure on most factory-installed superchargers.
6. An intercooler is used on many turbocharged and
some supercharged engines to reduce the
temperature of air entering the engine for
increased power.
7. A wastegate is used on most turbocharger systems
to limit and control boost pressures, as well as a
relief valve, to keep the speed of the turbine wheel
from slowing down during engine deceleration.
Automotive Fuel and Emissions Control Systems, 2/e
By James D. Halderman and Jim Linder
© 2009 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
REVIEW QUESTIONS
1. What are the reasons why supercharging
increases engine power?
2. How does the bypass valve work on a
supercharged engine?
3. What are the advantages and disadvantages of
supercharging?
4. What are the advantages and disadvantages of
turbocharging?
5. What turbocharger control valves are needed for
proper engine operation?
Automotive Fuel and Emissions Control Systems, 2/e
By James D. Halderman and Jim Linder
© 2009 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
CHAPTER QUIZ
1. Boost pressure is generally measured in _____.
a)
b)
c)
d)
in. Hg
PSI
in. H2O
in. lb
Automotive Fuel and Emissions Control Systems, 2/e
By James D. Halderman and Jim Linder
© 2009 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
CHAPTER QUIZ
1. Boost pressure is generally measured in _____.
a)
b)
c)
d)
in. Hg
PSI
in. H2O
in. lb
Automotive Fuel and Emissions Control Systems, 2/e
By James D. Halderman and Jim Linder
© 2009 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
CHAPTER QUIZ
2. Two types of superchargers are _____.
a)
b)
c)
d)
Rotary and reciprocating
Roots-type and centrifugal
Double and single acting
Turbine and piston
Automotive Fuel and Emissions Control Systems, 2/e
By James D. Halderman and Jim Linder
© 2009 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
CHAPTER QUIZ
2. Two types of superchargers are _____.
a)
b)
c)
d)
Rotary and reciprocating
Roots-type and centrifugal
Double and single acting
Turbine and piston
Automotive Fuel and Emissions Control Systems, 2/e
By James D. Halderman and Jim Linder
© 2009 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
CHAPTER QUIZ
3. Which valve is used on a factory supercharger to
limit boost?
a)
b)
c)
d)
A bypass valve
A wastegate
A blow-off valve
An air valve
Automotive Fuel and Emissions Control Systems, 2/e
By James D. Halderman and Jim Linder
© 2009 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
CHAPTER QUIZ
3. Which valve is used on a factory supercharger to
limit boost?
a)
b)
c)
d)
A bypass valve
A wastegate
A blow-off valve
An air valve
Automotive Fuel and Emissions Control Systems, 2/e
By James D. Halderman and Jim Linder
© 2009 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
CHAPTER QUIZ
4. How are most superchargers lubricated?
a) By engine oil under pressure through lines from the
engine
b) By an internal oil reservoir
c) By greased bearings
d) No lubrication is needed because the incoming air cools
the supercharger
Automotive Fuel and Emissions Control Systems, 2/e
By James D. Halderman and Jim Linder
© 2009 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
CHAPTER QUIZ
4. How are most superchargers lubricated?
a) By engine oil under pressure through lines from the
engine
b) By an internal oil reservoir
c) By greased bearings
d) No lubrication is needed because the incoming air cools
the supercharger
Automotive Fuel and Emissions Control Systems, 2/e
By James D. Halderman and Jim Linder
© 2009 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
CHAPTER QUIZ
5. How are most turbochargers lubricated?
a) By engine oil under pressure through lines from the
engine
b) By an internal oil reservoir
c) By greased bearings
d) No lubrication is needed because the incoming air cools
the supercharger
Automotive Fuel and Emissions Control Systems, 2/e
By James D. Halderman and Jim Linder
© 2009 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
CHAPTER QUIZ
5. How are most turbochargers lubricated?
a) By engine oil under pressure through lines from the
engine
b) By an internal oil reservoir
c) By greased bearings
d) No lubrication is needed because the incoming air cools
the supercharger
Automotive Fuel and Emissions Control Systems, 2/e
By James D. Halderman and Jim Linder
© 2009 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
CHAPTER QUIZ
6. Two technicians are discussing the term “turbo
lag.” Technician A says that it refers to the delay
between when the exhaust leaves the cylinder
and when it contacts the turbine blades of the
turbocharger. Technician B says that it refers to
the delay in boost pressure that occurs when the
throttle is first opened. Which technician is
correct?
a)
b)
c)
d)
Technician A only
Technician B only
Both Technicians A and B
Neither Technician A nor B
Automotive Fuel and Emissions Control Systems, 2/e
By James D. Halderman and Jim Linder
© 2009 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
CHAPTER QUIZ
6. Two technicians are discussing the term “turbo
lag.” Technician A says that it refers to the delay
between when the exhaust leaves the cylinder
and when it contacts the turbine blades of the
turbocharger. Technician B says that it refers to
the delay in boost pressure that occurs when the
throttle is first opened. Which technician is
correct?
a)
b)
c)
d)
Technician A only
Technician B only
Both Technicians A and B
Neither Technician A nor B
Automotive Fuel and Emissions Control Systems, 2/e
By James D. Halderman and Jim Linder
© 2009 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
CHAPTER QUIZ
7. What is the purpose of an intercooler?
a)
b)
c)
d)
To reduce the temperature of the air entering the engine
To cool the turbocharger
To cool the engine oil on a turbocharged engine
To cool the exhaust before it enters the turbocharger
Automotive Fuel and Emissions Control Systems, 2/e
By James D. Halderman and Jim Linder
© 2009 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
CHAPTER QUIZ
7. What is the purpose of an intercooler?
a) To reduce the temperature of the air entering the
engine
b) To cool the turbocharger
c) To cool the engine oil on a turbocharged engine
d) To cool the exhaust before it enters the turbocharger
Automotive Fuel and Emissions Control Systems, 2/e
By James D. Halderman and Jim Linder
© 2009 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
CHAPTER QUIZ
8. Which type of relief valve used on a turbocharged
engine is noisy?
a)
b)
c)
d)
A bypass valve
A BOV
A dump valve
Both b and c
Automotive Fuel and Emissions Control Systems, 2/e
By James D. Halderman and Jim Linder
© 2009 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
CHAPTER QUIZ
8. Which type of relief valve used on a turbocharged
engine is noisy?
a)
b)
c)
d)
A bypass valve
A BOV
A dump valve
Both b and c
Automotive Fuel and Emissions Control Systems, 2/e
By James D. Halderman and Jim Linder
© 2009 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
CHAPTER QUIZ
9. Technician A says that a stuck-open wastegate
can cause the engine to burn oil. Technician B
says that a clogged PCV system can cause the
engine to burn oil. Which technician is correct?
a)
b)
c)
d)
Technician A only
Technician B only
Both Technicians A and B
Neither Technician A nor B
Automotive Fuel and Emissions Control Systems, 2/e
By James D. Halderman and Jim Linder
© 2009 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
CHAPTER QUIZ
9. Technician A says that a stuck-open wastegate
can cause the engine to burn oil. Technician B
says that a clogged PCV system can cause the
engine to burn oil. Which technician is correct?
a)
b)
c)
d)
Technician A only
Technician B only
Both Technicians A and B
Neither Technician A nor B
Automotive Fuel and Emissions Control Systems, 2/e
By James D. Halderman and Jim Linder
© 2009 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
CHAPTER QUIZ
10. What service operation is most important on
engines equipped with a turbocharger?
a)
b)
c)
d)
Replacing the air filter regularly
Replacing the fuel filter regularly
Regular oil changes
Regular exhaust system maintenance
Automotive Fuel and Emissions Control Systems, 2/e
By James D. Halderman and Jim Linder
© 2009 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
CHAPTER QUIZ
10. What service operation is most important on
engines equipped with a turbocharger?
a)
b)
c)
d)
Replacing the air filter regularly
Replacing the fuel filter regularly
Regular oil changes
Regular exhaust system maintenance
Automotive Fuel and Emissions Control Systems, 2/e
By James D. Halderman and Jim Linder
© 2009 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458