at 43 ch 6 intake and exhaust
TRANSCRIPT
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Automotive Fuel and Emissions Control Systems, 2/eBy James D. Halderman and Jim Linder
2009 Pearson Higher Education, Inc.Pearson Prentice Hall - Upper Saddle River, NJ 07458
OBJECTIVES
After studying Chapter 6, the reader should be able to:1. Describe how the proper grade ofgasoline affects
engine performance.
2. List gasoline purchasing hints.
3. Discuss how volatility affects driveability.
4. Explain how oxygenated fuels can reduce CO
exhaust emissions.
5. Discuss the advantages and disadvantages ofvarious alternative fuels.
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Automotive Fuel and Emissions Control Systems, 2/eBy James D. Halderman and Jim Linder
2009 Pearson Higher Education, Inc.Pearson Prentice Hall - Upper Saddle River, NJ 07458
AIR INTAKE FILTRATION
Gasoline must be mixedwith air to form a
combustible mixture.
Air movement into an
engine occurs due to low
pressure (vacuum) being
created in the engine.
FIGURE 6-1 Downward movement ofthepiston lowers the air pressure inside the
combustion chamber. The pressure
differential between the atmosphere and
the inside of the engine forces air into the
engine.
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Automotive Fuel and Emissions Control Systems, 2/eBy James D. Halderman and Jim Linder
2009 Pearson Higher Education, Inc.Pearson Prentice Hall - Upper Saddle River, NJ 07458
AIR INTAKE FILTRATION
FIGURE 6-2 Dust and dirt in the air are trapped in
the airfilter so they do not enter the engine.
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Automotive Fuel and Emissions Control Systems, 2/eBy James D. Halderman and Jim Linder
2009 Pearson Higher Education, Inc.Pearson Prentice Hall - Upper Saddle River, NJ 07458
AIR INTAKE FILTRATION
Filter Replacement
Air Filter Elements
Remotely Mounted Air
Filters and Ducts
FIGURE 6-3 Most airfilter
housings are located on the side
of the engine compartment and
use flexible rubber hose to direct
the airflow into the throttle body of
the engine.
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Automotive Fuel and Emissions Control Systems, 2/eBy James D. Halderman and Jim Linder
2009 Pearson Higher Education, Inc.Pearson Prentice Hall - Upper Saddle River, NJ 07458
ALWAYS CHECK THE AIR FILTER
FIGURE 6-4 (a) Note the discovery as the airfilter housing was opened during service
on a Pontiac Bonneville. The nuts were obviously deposited by squirrels (or some
other animal). (b) Not only was the housing filled with nuts, but also this airfilter was
extremely dirty, indicating that this vehicle had not been serviced for a long time.
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Automotive Fuel and Emissions Control Systems, 2/eBy James D. Halderman and Jim Linder
2009 Pearson Higher Education, Inc.Pearson Prentice Hall - Upper Saddle River, NJ 07458
ENGINE AIR TEMPERATURE REQUIREMENTS
Some form of thermostatic control has been usedon vehicles equipped with a throttle-body fuel
injection to control intake air temperature for
improved driveability.
An air control valve or damper permits the air intakeof:
Heated airfrom the heat stove
Cooler airfrom the snorkel or cold-air duct
A combination ofboth
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Automotive Fuel and Emissions Control Systems, 2/eBy James D. Halderman and Jim Linder
2009 Pearson Higher Education, Inc.Pearson Prentice Hall - Upper Saddle River, NJ 07458
WHAT DOES THIS TUBE DO?
FIGURE 6-5 A resonance tube, called a Helmholtz resonator, is used on the intake
duct between the airfilter and the throttle body to reduce air intake noise during
engine acceleration.
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Automotive Fuel and Emissions Control Systems, 2/eBy James D. Halderman and Jim Linder
2009 Pearson Higher Education, Inc.Pearson Prentice Hall - Upper Saddle River, NJ 07458
THROTTLE-BODY INJECTION INTAKE
MANIFOLDS
Athrottle-body
fuel injector
forces finely divided
droplets of liquid fuel into
the incoming air to form a
combustible airfuel
mixture.
FIGURE 6-6 A throttle-body injection (TBI)
unit used on a GM V-6 engine.
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Automotive Fuel and Emissions Control Systems, 2/eBy James D. Halderman and Jim Linder
2009 Pearson Higher Education, Inc.Pearson Prentice Hall - Upper Saddle River, NJ 07458
THROTTLE-BODY INJECTION INTAKE
MANIFOLDS
FIGURE 6-7 Heavy fuel droplets separate as they
flow around an abrupt bend in an intake manifold.
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Automotive Fuel and Emissions Control Systems, 2/eBy James D. Halderman and Jim Linder
2009 Pearson Higher Education, Inc.Pearson Prentice Hall - Upper Saddle River, NJ 07458
PORT FUEL-INJECTION INTAKE MANIFOLDS
The size and shape ofport fuel-injected engineintake manifolds can be optimized because the only
thing in the manifold is air.
The fuel injection is located in the intake manifold
about 3 to 4 inches (70 to 100 mm) from the intakevalve.
Therefore, the runner length and shape are
designed for tuning only.
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Automotive Fuel and Emissions Control Systems, 2/eBy James D. Halderman and Jim Linder
2009 Pearson Higher Education, Inc.Pearson Prentice Hall - Upper Saddle River, NJ 07458
PORT FUEL-INJECTION INTAKE MANIFOLDS
FIGURE 6-8 The graph shows the effect ofsonic tuning of the intake manifold
runners. The longer runners increase the torque peak and move it to a lower
RPM. The 600-mm-long intake runner is about 24 inches long.
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Automotive Fuel and Emissions Control Systems, 2/eBy James D. Halderman and Jim Linder
2009 Pearson Higher Education, Inc.Pearson Prentice Hall - Upper Saddle River, NJ 07458
PORT FUEL-INJECTION INTAKE MANIFOLDS
FIGURE 6-9 Airflow through the large diameter upper intake manifold is
distributed to smaller diameter individual runners in the lower manifold in this
two-piece manifold design.
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Automotive Fuel and Emissions Control Systems, 2/eBy James D. Halderman and Jim Linder
2009 Pearson Higher Education, Inc.Pearson Prentice Hall - Upper Saddle River, NJ 07458
VARIABLE INTAKES
Many intake mani
folds aredesigned to provide both
short runners, best for
higher engine speed power,
and longer runners, best for
lower engine speed torque.
FIGURE 6-10 The airflowing into the
engine can be directed through long or
short runners for best performance and
fuel economy.
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Automotive Fuel and Emissions Control Systems, 2/eBy James D. Halderman and Jim Linder
2009 Pearson Higher Education, Inc.Pearson Prentice Hall - Upper Saddle River, NJ 07458
PLASTIC INTAKE MANIFOLDS
Plastic intake mani
foldshave smoother interior
surfaces than do other
types ofmanifolds,
resulting in greater airflow.
FIGURE 6-11 Many plastic intake
manifolds are constructed using many
parts glued together to form complex
passages for airflow into the engine.
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Automotive Fuel and Emissions Control Systems, 2/eBy James D. Halderman and Jim Linder
2009 Pearson Higher Education, Inc.Pearson Prentice Hall - Upper Saddle River, NJ 07458
PLASTIC INTAKE MANIFOLDS
FIGURE 6-12 The exhaust gas recirculation system is more efficient at controlling
NOX emissions if the exhaust gases are cooled. A long metal tube between the
exhaust manifold and the intake manifold allows the exhaust gases to cool before
entering the engine.
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Automotive Fuel and Emissions Control Systems, 2/eBy James D. Halderman and Jim Linder
2009 Pearson Higher Education, Inc.Pearson Prentice Hall - Upper Saddle River, NJ 07458
UPPER AND LOWER INTAKE MANIFOLDS
Many intake manifolds are constructed in two parts. A lower section, usually called the plenum, attaches to
the cylinder heads and includes passages from the intake
ports.
A
n upper manifold connects to the lower unit and includesthe long passages needed to help provide the ram effect
that helps the engine deliver maximum torque at low
engine speeds. The throttle body attaches to the upper
intake.
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Automotive Fuel and Emissions Control Systems, 2/eBy James D. Halderman and Jim Linder
2009 Pearson Higher Education, Inc.Pearson Prentice Hall - Upper Saddle River, NJ 07458
EXHAUST MANIFOLD DESIGN
The exhaust mani
fold isdesigned to collect high-
temperature spent gases
from the head exhaust
ports.
FIGURE 6-13 The exhaust gases are
pushed out of the cylinder by the piston on
the exhaust stroke.
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Automotive Fuel and Emissions Control Systems, 2/eBy James D. Halderman and Jim Linder
2009 Pearson Higher Education, Inc.Pearson Prentice Hall - Upper Saddle River, NJ 07458
EXHAUST MANIFOLD DESIGN
FIGURE 6-14 This exhaust manifold has a
heat shield to help retain the heat and help
reduce exhaust emissions.
FIGURE 6-15 Many exhaust manifolds are
constructed ofpressed steel and are free
flowing to improve engine performance.
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Automotive Fuel and Emissions Control Systems, 2/eBy James D. Halderman and Jim Linder
2009 Pearson Higher Education, Inc.Pearson Prentice Hall - Upper Saddle River, NJ 07458
HOW CAN A CRACKED EXHAUST MANIFOLD
AFFECT ENGINE PERFORMANCE?
FIGURE 6-16A crack in an exhaust manifold is often not this visible. A
crack in the exhaust manifold upstream of the oxygen sensor can fool the
sensor and affect engine operation.
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Automotive Fuel and Emissions Control Systems, 2/eBy James D. Halderman and Jim Linder
2009 Pearson Higher Education, Inc.Pearson Prentice Hall - Upper Saddle River, NJ 07458
EXHAUST MANIFOLD GASKETS
Gaskets are used on newengines with tubing- or
header-type exhaust
manifolds.
The gaskets often include
heat shields to keepexhaust heat from the spark
plugs and spark plug
cables.
They may have severallayers ofsteel for high-
temperature sealing.
FIGURE 6-17 Typical exhaust manifoldgaskets. Note how they are laminated to
allow the exhaust manifold to expand and
contract due to heating and cooling.
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Automotive Fuel and Emissions Control Systems, 2/eBy James D. Halderman and Jim Linder
2009 Pearson Higher Education, Inc.Pearson Prentice Hall - Upper Saddle River, NJ 07458
THE CORRECT TOOLS SAVE TIME
FIGURE 6-18 An exhaust manifold spreader tool is a tool that is absolutely necessary
to use when reinstalling exhaust manifolds. When they are removed from the engine,
they tend to warp slightly even though the engine is allowed to cool before being
removed. The spreader tool allows the technician to line up the bolt holes without doing
any harm to the manifold.
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Automotive Fuel and Emissions Control Systems, 2/eBy James D. Halderman and Jim Linder
2009 Pearson Higher Education, Inc.Pearson Prentice Hall - Upper Saddle River, NJ 07458
MUFFLERS
Sound is air vibration. When the vibrations are large, the sound is loud.
The muffler catches the large bursts ofhigh-pressure
exhaust gas from the cylinder, smoothing out the pressure
pulses and allowing them to be released at an even and
constant rate.
FIGURE 6-19 Exhaust gases expand and cool as they travel through the passages in the muffler.
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Automotive Fuel and Emissions Control Systems, 2/eBy James D. Halderman and Jim Linder
2009 Pearson Higher Education, Inc.Pearson Prentice Hall - Upper Saddle River, NJ 07458
WHY IS THERE A HOLE IN MY MUFFLER?
FIGURE 6-20A hole in the muffler allows condensed water to escape.
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Automotive Fuel and Emissions Control Systems, 2/eBy James D. Halderman and Jim Linder
2009 Pearson Higher Education, Inc.Pearson Prentice Hall - Upper Saddle River, NJ 07458
MORE AIRFLOW MORE POWER
FIGURE 6-21 A high-performance aftermarket airfilter often can increase airflow
into the engine for more power.
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Automotive Fuel and Emissions Control Systems, 2/eBy James D. Halderman and Jim Linder
2009 Pearson Higher Education, Inc.Pearson Prentice Hall - Upper Saddle River, NJ 07458
SUMMARY
1. All air entering an engine must be filtered.
2. Engines that use throttle-body injection units are equippedwith intake manifolds that keep the airflow speed throughthe manifold at 50 to 300 feet per second.
3. Most intake manifolds have an EGR valve that regulates
the amount of recirculated exhaust that enters the engineto reduce NOX emissions.
4. Exhaust manifolds can be made from cast iron or stainlesssteel.
5. The exhaust system also contains a catalytic converter,
exhaust pipes, and muffler. The entire exhaust system issupported by rubber hangers that isolate the noise andvibration of the exhaust from the rest of the vehicle.