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© 2011 Pearson Education, Inc.All Rights Reserved
Automotive Technology, Fourth EditionJames Halderman
INTAKE AND EXHAUST SYSTEMS
24
24 INTAKE AND EXHAUST SYSTEMS
Automotive Technology, Fourth EditionJames Halderman
© 2011 Pearson Education, Inc.All Rights Reserved
ObjectivesObjectives
• The student should be able to:– Prepare for ASE Engine Performance (A8)
certification test content area “C” (Air Induction and Exhaust Systems Diagnosis and Repair).
– Discuss the purpose and function of intake air system components.
24 INTAKE AND EXHAUST SYSTEMS
Automotive Technology, Fourth EditionJames Halderman
© 2011 Pearson Education, Inc.All Rights Reserved
ObjectivesObjectives
• The student should be able to:– Explain the differences between throttle-
body fuel-injection manifolds and port fuel-injection manifolds.
– List the materials used in exhaust manifolds and exhaust systems.
– Describe the purpose and function of the exhaust system components.
24 INTAKE AND EXHAUST SYSTEMS
Automotive Technology, Fourth EditionJames Halderman
© 2011 Pearson Education, Inc.All Rights Reserved
AIR INTAKE FILTRATIONAIR INTAKE FILTRATION
24 INTAKE AND EXHAUST SYSTEMS
Automotive Technology, Fourth EditionJames Halderman
© 2011 Pearson Education, Inc.All Rights Reserved
Air Intake FiltrationAir Intake Filtration
• Need for Air Filtering– Gasoline must be mixed with air for
combustion– Air movement into engine occurs due to
vacuum created in engine
24 INTAKE AND EXHAUST SYSTEMS
Automotive Technology, Fourth EditionJames Halderman
© 2011 Pearson Education, Inc.All Rights Reserved
Figure 24-1 Downward movement of the piston 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.
24 INTAKE AND EXHAUST SYSTEMS
Automotive Technology, Fourth EditionJames Halderman
© 2011 Pearson Education, Inc.All Rights Reserved
Air Intake FiltrationAir Intake Filtration
• Need for Air Filtering– Dirt in air cannot reach engine– Air filter and cleaner remove contaminants
24 INTAKE AND EXHAUST SYSTEMS
Automotive Technology, Fourth EditionJames Halderman
© 2011 Pearson Education, Inc.All Rights Reserved
Air Intake FiltrationAir Intake Filtration
• Need for Air Filtering– Three jobs of air cleaner and filter
• Clean air before it is mixed with fuel• Silence intake noise
24 INTAKE AND EXHAUST SYSTEMS
Automotive Technology, Fourth EditionJames Halderman
© 2011 Pearson Education, Inc.All Rights Reserved
Air Intake FiltrationAir Intake Filtration
• Need for Air Filtering– Three jobs of air cleaner and filter
• Act as flame arrester in case of backfire
24 INTAKE AND EXHAUST SYSTEMS
Automotive Technology, Fourth EditionJames Halderman
© 2011 Pearson Education, Inc.All Rights Reserved
Air Intake FiltrationAir Intake Filtration
• Need for Air Filtering– Automotive engine uses 9,000 gallons
(34,000 liters) of air per gallon of gasoline in air-fuel ratio of 14.7:1 by weight
– Abrasive particles cause wear inside engine
24 INTAKE AND EXHAUST SYSTEMS
Automotive Technology, Fourth EditionJames Halderman
© 2011 Pearson Education, Inc.All Rights Reserved
Air Intake FiltrationAir Intake Filtration
• Need for Air Filtering– Filter is in air cleaner housing
• Stamped steel• Composite (usually nylon reinforced plastic)
24 INTAKE AND EXHAUST SYSTEMS
Automotive Technology, Fourth EditionJames Halderman
© 2011 Pearson Education, Inc.All Rights Reserved
Air Intake FiltrationAir Intake Filtration
• Air Filter Elements– Paper air filter element most common– Paper stock contains tiny passages in fibers
24 INTAKE AND EXHAUST SYSTEMS
Automotive Technology, Fourth EditionJames Halderman
© 2011 Pearson Education, Inc.All Rights Reserved
Air Intake FiltrationAir Intake Filtration
• Air Filter Elements– Airflow passes through several fiber
surfaces– Fiber surfaces trap microscopic particles
24 INTAKE AND EXHAUST SYSTEMS
Automotive Technology, Fourth EditionJames Halderman
© 2011 Pearson Education, Inc.All Rights Reserved
Air Intake FiltrationAir Intake Filtration
• Air Filter Elements– Most air filters trap particles larger than 10
to 25 microns– NOTE: A person can see objects 40 microns
or larger in size. Human hair is about 50 microns in diameter.
24 INTAKE AND EXHAUST SYSTEMS
Automotive Technology, Fourth EditionJames Halderman
© 2011 Pearson Education, Inc.All Rights Reserved
Figure 24-2 Dust and dirt in the air are trapped in the air filter so they do not enter the engine.
24 INTAKE AND EXHAUST SYSTEMS
Automotive Technology, Fourth EditionJames Halderman
© 2011 Pearson Education, Inc.All Rights Reserved
Air Intake FiltrationAir Intake Filtration
• Filter Replacement– Manufacturers recommend cleaning or
replacing air filter elements at periodic intervals
– Replace filter before it becomes too dirty to be effective
24 INTAKE AND EXHAUST SYSTEMS
Automotive Technology, Fourth EditionJames Halderman
© 2011 Pearson Education, Inc.All Rights Reserved
Air Intake FiltrationAir Intake Filtration
• Remotely Mounted Air Filters and Ducts– Air cleaner and duct design depend on size,
shape, location, and vehicle body construction
– Port fuel-injection systems generally use horizontally mounted throttle body
24 INTAKE AND EXHAUST SYSTEMS
Automotive Technology, Fourth EditionJames Halderman
© 2011 Pearson Education, Inc.All Rights Reserved
Air Intake FiltrationAir Intake Filtration
• Remotely Mounted Air Filters and Ducts– Some systems have mass airflow (MAF)
sensor between throttle body and air cleaner
– Design issues make it is more efficient to use remote air cleaner placement
24 INTAKE AND EXHAUST SYSTEMS
Automotive Technology, Fourth EditionJames Halderman
© 2011 Pearson Education, Inc.All Rights Reserved
Figure 24-3 Most air filter 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.
24 INTAKE AND EXHAUST SYSTEMS
Automotive Technology, Fourth EditionJames Halderman
© 2011 Pearson Education, Inc.All Rights Reserved
Air Intake FiltrationAir Intake Filtration
• Remotely Mounted Air Filters and Ducts– Turbocharged engines require remote air
filter placement– Air filter connects to air inlet elbow on
turbocharger
24 INTAKE AND EXHAUST SYSTEMS
Automotive Technology, Fourth EditionJames Halderman
© 2011 Pearson Education, Inc.All Rights Reserved
Air Intake FiltrationAir Intake Filtration
• Remotely Mounted Air Filters and Ducts– Heat generated by turbocharger requires
remote placement of air filter– Air filter connected to turbocharger by
composite ducting
24 INTAKE AND EXHAUST SYSTEMS
Automotive Technology, Fourth EditionJames Halderman
© 2011 Pearson Education, Inc.All Rights Reserved
Air Intake FiltrationAir Intake Filtration
• Air Filter Restriction Indicator– Connections must be airtight– Vehicles driven in dusty conditions often
have air filter restriction indicators
24 INTAKE AND EXHAUST SYSTEMS
Automotive Technology, Fourth EditionJames Halderman
© 2011 Pearson Education, Inc.All Rights Reserved
Air Intake FiltrationAir Intake Filtration
• Air Filter Restriction Indicator– Device warns if filter is restricted and
needs replacement– Device operates by detecting drop in air
pressure
24 INTAKE AND EXHAUST SYSTEMS
Automotive Technology, Fourth EditionJames Halderman
© 2011 Pearson Education, Inc.All Rights Reserved
Air Intake FiltrationAir Intake Filtration
• Air Filter Restriction Indicator– Typical calibration of indicator
• 15 to 20 in. of water (in. H2O) for gasoline engines
24 INTAKE AND EXHAUST SYSTEMS
Automotive Technology, Fourth EditionJames Halderman
© 2011 Pearson Education, Inc.All Rights Reserved
Air Intake FiltrationAir Intake Filtration
• Air Filter Restriction Indicator– Typical calibration of indicator
• 20 to 30 in. of water (in. H2O) for diesel engines
24 INTAKE AND EXHAUST SYSTEMS
Automotive Technology, Fourth EditionJames Halderman
© 2011 Pearson Education, Inc.All Rights Reserved
Air Intake FiltrationAir Intake Filtration
• Air Filter Restriction Indicator– Unit of inches of water measures difference
in air pressure before and after air filter
24 INTAKE AND EXHAUST SYSTEMS
Automotive Technology, Fourth EditionJames Halderman
© 2011 Pearson Education, Inc.All Rights Reserved
Air Intake FiltrationAir Intake Filtration
• Air Filter Restriction Indicator– 28 in. of water equals pound per square
inch (PSI)– Some air filter restriction indicators use
electrical switch to light dash-mounted warning light
?
24 INTAKE AND EXHAUST SYSTEMS
Automotive Technology, Fourth EditionJames Halderman
© 2011 Pearson Education, Inc.All Rights Reserved
Figure 24-4 A typical air filter restriction indicator used on a General Motors truck engine. The indicator turns red when it detects enough restriction to require a filter replacement.
24 INTAKE AND EXHAUST SYSTEMS
Automotive Technology, Fourth EditionJames Halderman
© 2011 Pearson Education, Inc.All Rights Reserved
Figure 24-5 (a) Note the discovery as the air filter housing was opened during service on a Pontiac. The nuts were obviously deposited by squirrels (or some other animal).
24 INTAKE AND EXHAUST SYSTEMS
Automotive Technology, Fourth EditionJames Halderman
© 2011 Pearson Education, Inc.All Rights Reserved
Figure 24-5 (b) Not only was the housing filled with nuts, but also this air filter was extremely dirty, indicating that this vehicle had not been serviced for a long time.
24 INTAKE AND EXHAUST SYSTEMS
Automotive Technology, Fourth EditionJames Halderman
© 2011 Pearson Education, Inc.All Rights Reserved
Figure 24-6 A resonance tube, called a Helmholtz resonator, is used on the intake duct between the air filter and the throttle body to reduce air intake noise during engine acceleration.
24 INTAKE AND EXHAUST SYSTEMS
Automotive Technology, Fourth EditionJames Halderman
© 2011 Pearson Education, Inc.All Rights Reserved
THROTTLE-BODY THROTTLE-BODY INJECTION INTAKE INJECTION INTAKE
MANIFOLDSMANIFOLDS
24 INTAKE AND EXHAUST SYSTEMS
Automotive Technology, Fourth EditionJames Halderman
© 2011 Pearson Education, Inc.All Rights Reserved
Throttle-Body Injection Intake Throttle-Body Injection Intake ManifoldsManifolds
• Terminology– Intake manifold also called inlet manifold– Smooth engine operation occurs only when
each combustion chamber produces same pressure
24 INTAKE AND EXHAUST SYSTEMS
Automotive Technology, Fourth EditionJames Halderman
© 2011 Pearson Education, Inc.All Rights Reserved
Throttle-Body Injection Intake Throttle-Body Injection Intake ManifoldsManifolds
• Terminology– All cylinders must receive exactly same
quality and quantity of charge– Charges must have same physical
properties and air-fuel mixture
24 INTAKE AND EXHAUST SYSTEMS
Automotive Technology, Fourth EditionJames Halderman
© 2011 Pearson Education, Inc.All Rights Reserved
Throttle-Body Injection Intake Throttle-Body Injection Intake ManifoldsManifolds
• Terminology– Throttle-body fuel injector forces tiny
droplets of liquid fuel into incoming air to form combustible air-fuel mixture
24 INTAKE AND EXHAUST SYSTEMS
Automotive Technology, Fourth EditionJames Halderman
© 2011 Pearson Education, Inc.All Rights Reserved
Figure 24-7 A throttle-body injection (TBI) unit used on a GM V-6 engine.
24 INTAKE AND EXHAUST SYSTEMS
Automotive Technology, Fourth EditionJames Halderman
© 2011 Pearson Education, Inc.All Rights Reserved
Throttle-Body Injection Intake Throttle-Body Injection Intake ManifoldsManifolds
• Intake Air Speeds– Droplets begin to evaporate when they
leave throttle-body injector nozzles– Droplets stay in the charge as long as
charge flows at high velocities
24 INTAKE AND EXHAUST SYSTEMS
Automotive Technology, Fourth EditionJames Halderman
© 2011 Pearson Education, Inc.All Rights Reserved
Throttle-Body Injection Intake Throttle-Body Injection Intake ManifoldsManifolds
• Intake Air Speeds– At maximum engine speed, velocity may
reach 330 ft per second– Separation of droplets from charge as it
passes through manifold occurs when velocity drops below 50 ft per second
24 INTAKE AND EXHAUST SYSTEMS
Automotive Technology, Fourth EditionJames Halderman
© 2011 Pearson Education, Inc.All Rights Reserved
Throttle-Body Injection Intake Throttle-Body Injection Intake ManifoldsManifolds
• Intake Air Speeds– At idle speed, intake charge velocities may
drop below 50 ft per second
24 INTAKE AND EXHAUST SYSTEMS
Automotive Technology, Fourth EditionJames Halderman
© 2011 Pearson Education, Inc.All Rights Reserved
Throttle-Body Injection Intake Throttle-Body Injection Intake ManifoldsManifolds
• Intake Air Speeds– Manifold sizes and shapes represent
compromise• Cross section large enough for maximum
power
24 INTAKE AND EXHAUST SYSTEMS
Automotive Technology, Fourth EditionJames Halderman
© 2011 Pearson Education, Inc.All Rights Reserved
Throttle-Body Injection Intake Throttle-Body Injection Intake ManifoldsManifolds
• Intake Air Speeds– Manifold sizes and shapes represent
compromise• Cross section small enough so equal
mixtures reach each cylinder
24 INTAKE AND EXHAUST SYSTEMS
Automotive Technology, Fourth EditionJames Halderman
© 2011 Pearson Education, Inc.All Rights Reserved
Throttle-Body Injection Intake Throttle-Body Injection Intake ManifoldsManifolds
• Intake Air Speeds– Manifold sizes and shapes represent
compromise• Racing manifolds must be large enough to
reach maximum horsepower
24 INTAKE AND EXHAUST SYSTEMS
Automotive Technology, Fourth EditionJames Halderman
© 2011 Pearson Education, Inc.All Rights Reserved
Throttle-Body Injection Intake Throttle-Body Injection Intake ManifoldsManifolds
• Intake Air Speeds– Manifold sizes and shapes represent
compromise• Large size allows charge to move slowly
24 INTAKE AND EXHAUST SYSTEMS
Automotive Technology, Fourth EditionJames Halderman
© 2011 Pearson Education, Inc.All Rights Reserved
Throttle-Body Injection Intake Throttle-Body Injection Intake ManifoldsManifolds
• Intake Air Speeds– Manifold sizes and shapes represent
compromise• Fuel separation occurs at low engine speeds
24 INTAKE AND EXHAUST SYSTEMS
Automotive Technology, Fourth EditionJames Halderman
© 2011 Pearson Education, Inc.All Rights Reserved
Throttle-Body Injection Intake Throttle-Body Injection Intake ManifoldsManifolds
• Intake Air Speeds– Manifold sizes and shapes represent
compromise• Fuel separation leads to poor accelerator
response
24 INTAKE AND EXHAUST SYSTEMS
Automotive Technology, Fourth EditionJames Halderman
© 2011 Pearson Education, Inc.All Rights Reserved
Figure 24-8 Heavy fuel droplets separate as they flow around an abrupt bend in an intake manifold.
24 INTAKE AND EXHAUST SYSTEMS
Automotive Technology, Fourth EditionJames Halderman
© 2011 Pearson Education, Inc.All Rights Reserved
Throttle-Body Injection Intake Throttle-Body Injection Intake ManifoldsManifolds
• Intake Air Speeds– Standard passenger vehicle engines
designed for economy under light load, partial-throttle operation
24 INTAKE AND EXHAUST SYSTEMS
Automotive Technology, Fourth EditionJames Halderman
© 2011 Pearson Education, Inc.All Rights Reserved
Throttle-Body Injection Intake Throttle-Body Injection Intake ManifoldsManifolds
• Intake Air Speeds– Manifolds have smaller cross-sectional area
than racing engines– Small sizes keep flow velocities high
through normal operating speeds
24 INTAKE AND EXHAUST SYSTEMS
Automotive Technology, Fourth EditionJames Halderman
© 2011 Pearson Education, Inc.All Rights Reserved
PORT FUEL-INJECTIONPORT FUEL-INJECTIONINTAKE MANIFOLDSINTAKE MANIFOLDS
24 INTAKE AND EXHAUST SYSTEMS
Automotive Technology, Fourth EditionJames Halderman
© 2011 Pearson Education, Inc.All Rights Reserved
Port Fuel-Injection Intake ManifoldsPort Fuel-Injection Intake Manifolds
• Terminology– Size and shape of port fuel-injected engine
intake manifolds can be optimized because only air is in the manifold
24 INTAKE AND EXHAUST SYSTEMS
Automotive Technology, Fourth EditionJames Halderman
© 2011 Pearson Education, Inc.All Rights Reserved
Port Fuel-Injection Intake ManifoldsPort Fuel-Injection Intake Manifolds
• Terminology– Fuel injector located in intake manifold 3 to
4 in (70 to 100 mm) from intake valve
24 INTAKE AND EXHAUST SYSTEMS
Automotive Technology, Fourth EditionJames Halderman
© 2011 Pearson Education, Inc.All Rights Reserved
Port Fuel-Injection Intake ManifoldsPort Fuel-Injection Intake Manifolds
• Terminology– Runner length and shape designed for
tuning only– No need to keep air-fuel mixture
homogenized
24 INTAKE AND EXHAUST SYSTEMS
Automotive Technology, Fourth EditionJames Halderman
© 2011 Pearson Education, Inc.All Rights Reserved
Port Fuel-Injection Intake ManifoldsPort Fuel-Injection Intake Manifolds
• Terminology– Intake manifolds tuned to improve
performance• Long runners build low-RPM torque
24 INTAKE AND EXHAUST SYSTEMS
Automotive Technology, Fourth EditionJames Halderman
© 2011 Pearson Education, Inc.All Rights Reserved
Port Fuel-Injection Intake ManifoldsPort Fuel-Injection Intake Manifolds
• Terminology– Intake manifolds tuned to improve
performance• Shorter runners provide maximum high-RPM
power
24 INTAKE AND EXHAUST SYSTEMS
Automotive Technology, Fourth EditionJames Halderman
© 2011 Pearson Education, Inc.All Rights Reserved
Figure 24-9 The graph shows the effect of sonic tuning of the intake manifold runners. The longer runners increase the torque peak and move it to a lower RPM. The 600 mm intake runner is about 24 in. long.
24 INTAKE AND EXHAUST SYSTEMS
Automotive Technology, Fourth EditionJames Halderman
© 2011 Pearson Education, Inc.All Rights Reserved
Figure 24-10 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.
24 INTAKE AND EXHAUST SYSTEMS
Automotive Technology, Fourth EditionJames Halderman
© 2011 Pearson Education, Inc.All Rights Reserved
Throttle-Body Injection Intake Throttle-Body Injection Intake ManifoldsManifolds
• Variable Intakes– Some engines with four valve heads use
dual or variable intake runners– At low engine speeds, long intake runners
give low-speed torque
24 INTAKE AND EXHAUST SYSTEMS
Automotive Technology, Fourth EditionJames Halderman
© 2011 Pearson Education, Inc.All Rights Reserved
Throttle-Body Injection Intake Throttle-Body Injection Intake ManifoldsManifolds
• Variable Intakes– At high engine speeds, shorter intake
runners increase high-speed power– Many intake manifolds have both long and
short intake runners– Valves that control air flow are computer
controlled
24 INTAKE AND EXHAUST SYSTEMS
Automotive Technology, Fourth EditionJames Halderman
© 2011 Pearson Education, Inc.All Rights Reserved
Figure 24-11 The air flowing into the engine can be directed through long or short runners for best performance and fuel economy.
24 INTAKE AND EXHAUST SYSTEMS
Automotive Technology, Fourth EditionJames Halderman
© 2011 Pearson Education, Inc.All Rights Reserved
Throttle-Body Injection Intake Throttle-Body Injection Intake ManifoldsManifolds
• Plastic Intake Manifolds– Most intake manifolds are made from
thermoplastic molded – Some manifolds are molded in two parts
and bonded together
24 INTAKE AND EXHAUST SYSTEMS
Automotive Technology, Fourth EditionJames Halderman
© 2011 Pearson Education, Inc.All Rights Reserved
Throttle-Body Injection Intake Throttle-Body Injection Intake ManifoldsManifolds
• Plastic Intake Manifolds– Plastic intake manifolds have smoother
interior surfaces for greater airflow
24 INTAKE AND EXHAUST SYSTEMS
Automotive Technology, Fourth EditionJames Halderman
© 2011 Pearson Education, Inc.All Rights Reserved
Figure 24-12 Many plastic intake manifolds are constructed using many parts glued together to form complex passages for airflow into the engine.
24 INTAKE AND EXHAUST SYSTEMS
Automotive Technology, Fourth EditionJames Halderman
© 2011 Pearson Education, Inc.All Rights Reserved
Throttle-Body Injection Intake Throttle-Body Injection Intake ManifoldsManifolds
• Upper and Lower Intake Manifolds– Many intake manifolds are constructed in
two parts• Lower section attaches to cylinder heads
and have passages from intake ports
24 INTAKE AND EXHAUST SYSTEMS
Automotive Technology, Fourth EditionJames Halderman
© 2011 Pearson Education, Inc.All Rights Reserved
Throttle-Body Injection Intake Throttle-Body Injection Intake ManifoldsManifolds
• Upper and Lower Intake Manifolds– Many intake manifolds are constructed in
two parts• Upper manifold, called plenum, connects to
lower unit
24 INTAKE AND EXHAUST SYSTEMS
Automotive Technology, Fourth EditionJames Halderman
© 2011 Pearson Education, Inc.All Rights Reserved
Throttle-Body Injection Intake Throttle-Body Injection Intake ManifoldsManifolds
• Upper and Lower Intake Manifolds– Many intake manifolds are constructed in
two parts• Upper manifold includes long passages
24 INTAKE AND EXHAUST SYSTEMS
Automotive Technology, Fourth EditionJames Halderman
© 2011 Pearson Education, Inc.All Rights Reserved
Throttle-Body Injection Intake Throttle-Body Injection Intake ManifoldsManifolds
• Upper and Lower Intake Manifolds– Many intake manifolds are constructed in
two parts• Throttle body attaches to upper intake
24 INTAKE AND EXHAUST SYSTEMS
Automotive Technology, Fourth EditionJames Halderman
© 2011 Pearson Education, Inc.All Rights Reserved
Throttle-Body Injection Intake Throttle-Body Injection Intake ManifoldsManifolds
• Upper and Lower Intake Manifolds– Two-part intake manifolds allow easier
manufacturing and assembly– Two-part intake manifold create additional
locations for leaks
24 INTAKE AND EXHAUST SYSTEMS
Automotive Technology, Fourth EditionJames Halderman
© 2011 Pearson Education, Inc.All Rights Reserved
Throttle-Body Injection Intake Throttle-Body Injection Intake ManifoldsManifolds
• Upper and Lower Intake Manifolds– Leak in lower intake manifold can affect
operation of engine– Leak in upper intake manifold results in
vacuum leak only
24 INTAKE AND EXHAUST SYSTEMS
Automotive Technology, Fourth EditionJames Halderman
© 2011 Pearson Education, Inc.All Rights Reserved
EXHAUST GASEXHAUST GASRECIRCULATION RECIRCULATION
PASSAGEPASSAGE
24 INTAKE AND EXHAUST SYSTEMS
Automotive Technology, Fourth EditionJames Halderman
© 2011 Pearson Education, Inc.All Rights Reserved
Exhaust Gas Recirculation PassagesExhaust Gas Recirculation Passages
• Purpose and Function– To reduce emission of oxides of nitrogen
(NOx), engines have exhaust gas recirculation (EGR) valves
24 INTAKE AND EXHAUST SYSTEMS
Automotive Technology, Fourth EditionJames Halderman
© 2011 Pearson Education, Inc.All Rights Reserved
Exhaust Gas Recirculation PassagesExhaust Gas Recirculation Passages
• Purpose and Function– Most EGR valves are mounted on intake
manifold– Some newer engines do not require EGR
system
24 INTAKE AND EXHAUST SYSTEMS
Automotive Technology, Fourth EditionJames Halderman
© 2011 Pearson Education, Inc.All Rights Reserved
Exhaust Gas Recirculation PassagesExhaust Gas Recirculation Passages
• Purpose and Function– EGR valve opens at speeds above idle– EGR valve allows small portion of exhaust
gas (5% to 10%) to enter intake manifold
24 INTAKE AND EXHAUST SYSTEMS
Automotive Technology, Fourth EditionJames Halderman
© 2011 Pearson Education, Inc.All Rights Reserved
Exhaust Gas Recirculation PassagesExhaust Gas Recirculation Passages
• Purpose and Function– EGR system interconnects exhaust and
intake manifolds– EGR valve controls gas flow through
passages• On V-type engines, intake manifold
crossover provides exhaust gas
24 INTAKE AND EXHAUST SYSTEMS
Automotive Technology, Fourth EditionJames Halderman
© 2011 Pearson Education, Inc.All Rights Reserved
Exhaust Gas Recirculation PassagesExhaust Gas Recirculation Passages
• Purpose and Function– EGR valve controls gas flow through
passages• On inline-type engines, external tube carries
exhaust gas to EGR valve
24 INTAKE AND EXHAUST SYSTEMS
Automotive Technology, Fourth EditionJames Halderman
© 2011 Pearson Education, Inc.All Rights Reserved
Exhaust Gas Recirculation PassagesExhaust Gas Recirculation Passages
• Exhaust Gas Coolers– Exhaust gases are more effective in
reducing NOx emissions if exhaust is cooled before entering cylinders
– Tube is long so exhaust gas is cooled before entering EGR valve
24 INTAKE AND EXHAUST SYSTEMS
Automotive Technology, Fourth EditionJames Halderman
© 2011 Pearson Education, Inc.All Rights Reserved
Figure 24-13 A typical long exhaust gas line used to cool the exhaust gases before being recirculated back into the intake manifold.
24 INTAKE AND EXHAUST SYSTEMS
Automotive Technology, Fourth EditionJames Halderman
© 2011 Pearson Education, Inc.All Rights Reserved
EXHAUST MANIFOLDSEXHAUST MANIFOLDS
24 INTAKE AND EXHAUST SYSTEMS
Automotive Technology, Fourth EditionJames Halderman
© 2011 Pearson Education, Inc.All Rights Reserved
Exhaust ManifoldsExhaust Manifolds
• Purpose and Function– Exhaust manifold collects high-temperature
spend gases from head exhaust ports and connects them to exhaust system
24 INTAKE AND EXHAUST SYSTEMS
Automotive Technology, Fourth EditionJames Halderman
© 2011 Pearson Education, Inc.All Rights Reserved
Figure 24-14 The exhaust gases are pushed out of the cylinder by the piston on the exhaust stroke.
24 INTAKE AND EXHAUST SYSTEMS
Automotive Technology, Fourth EditionJames Halderman
© 2011 Pearson Education, Inc.All Rights Reserved
Exhaust ManifoldsExhaust Manifolds
• Purpose and Function– Hot gases are sent to exhaust pipe,
catalytic converter, muffler, resonator, and tailpipe
24 INTAKE AND EXHAUST SYSTEMS
Automotive Technology, Fourth EditionJames Halderman
© 2011 Pearson Education, Inc.All Rights Reserved
Exhaust ManifoldsExhaust Manifolds
• Purpose and Function– Exhaust system designed to meet these
needs• Provide least possible restriction or
backpressure
24 INTAKE AND EXHAUST SYSTEMS
Automotive Technology, Fourth EditionJames Halderman
© 2011 Pearson Education, Inc.All Rights Reserved
Exhaust ManifoldsExhaust Manifolds
• Purpose and Function– Exhaust system designed to meet these
needs• Keep exhaust noise to minimum
24 INTAKE AND EXHAUST SYSTEMS
Automotive Technology, Fourth EditionJames Halderman
© 2011 Pearson Education, Inc.All Rights Reserved
Exhaust ManifoldsExhaust Manifolds
• Purpose and Function– Exhaust gas temperature varies
24 INTAKE AND EXHAUST SYSTEMS
Automotive Technology, Fourth EditionJames Halderman
© 2011 Pearson Education, Inc.All Rights Reserved
Exhaust ManifoldsExhaust Manifolds
• Purpose and Function– Manifold must operate at engine idle and
full power
24 INTAKE AND EXHAUST SYSTEMS
Automotive Technology, Fourth EditionJames Halderman
© 2011 Pearson Education, Inc.All Rights Reserved
Exhaust ManifoldsExhaust Manifolds
• Purpose and Function– Temperature of exhaust manifold can
exceed 1,500°F (815°C)
24 INTAKE AND EXHAUST SYSTEMS
Automotive Technology, Fourth EditionJames Halderman
© 2011 Pearson Education, Inc.All Rights Reserved
Exhaust ManifoldsExhaust Manifolds
• Construction– Most exhaust manifolds are made from the
following• Cast iron• Steel tubing
24 INTAKE AND EXHAUST SYSTEMS
Automotive Technology, Fourth EditionJames Halderman
© 2011 Pearson Education, Inc.All Rights Reserved
Exhaust ManifoldsExhaust Manifolds
• Construction– Manifold temperature usually reaches high-
temperature extremes– Manifold is bolted to head to allow
expansion and contraction
24 INTAKE AND EXHAUST SYSTEMS
Automotive Technology, Fourth EditionJames Halderman
© 2011 Pearson Education, Inc.All Rights Reserved
Exhaust ManifoldsExhaust Manifolds
• Construction– Many manifolds have heat shields to
protect spark plug wires and improve emissions
24 INTAKE AND EXHAUST SYSTEMS
Automotive Technology, Fourth EditionJames Halderman
© 2011 Pearson Education, Inc.All Rights Reserved
Figure 24-16 Many exhaust manifolds are constructed of steel tubing and are free flowing to improve engine performance.
24 INTAKE AND EXHAUST SYSTEMS
Automotive Technology, Fourth EditionJames Halderman
© 2011 Pearson Education, Inc.All Rights Reserved
Exhaust ManifoldsExhaust Manifolds
• Exhaust Manifold Gaskets– Exhaust heat expands manifold more than
head– Heat causes exhaust manifold to slide on
sealing surface of head
24 INTAKE AND EXHAUST SYSTEMS
Automotive Technology, Fourth EditionJames Halderman
© 2011 Pearson Education, Inc.All Rights Reserved
Exhaust ManifoldsExhaust Manifolds
• Exhaust Manifold Gaskets– Heat causes thermal stress– Removing manifold for service may cause
manifold to warp
24 INTAKE AND EXHAUST SYSTEMS
Automotive Technology, Fourth EditionJames Halderman
© 2011 Pearson Education, Inc.All Rights Reserved
Exhaust ManifoldsExhaust Manifolds
• Exhaust Manifold Gaskets– Manifold gaskets seal slightly warped
manifolds– If gasket has facing on one side only, put
facing against head
24 INTAKE AND EXHAUST SYSTEMS
Automotive Technology, Fourth EditionJames Halderman
© 2011 Pearson Education, Inc.All Rights Reserved
Exhaust ManifoldsExhaust Manifolds
• Exhaust Manifold Gaskets– Gaskets are used on new engines with
tubing- or header-type exhaust manifolds– Gaskets may have several layers of steel
for high-temperature sealing
?
24 INTAKE AND EXHAUST SYSTEMS
Automotive Technology, Fourth EditionJames Halderman
© 2011 Pearson Education, Inc.All Rights Reserved
Figure 24-18 Typical exhaust manifold gaskets. Note how they are laminated to allow the exhaust manifold to expand and contract due to heating and cooling.
24 INTAKE AND EXHAUST SYSTEMS
Automotive Technology, Fourth EditionJames Halderman
© 2011 Pearson Education, Inc.All Rights Reserved
Figure 24-19 An exhaust manifold spreader tool is absolutely necessary when reinstalling exhaust manifolds. When they are removed from the engine, the manifolds 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 harming the manifold.
24 INTAKE AND EXHAUST SYSTEMS
Automotive Technology, Fourth EditionJames Halderman
© 2011 Pearson Education, Inc.All Rights Reserved
Exhaust ManifoldsExhaust Manifolds
• Exhaust Manifold Gaskets– Many new engines do not use gaskets with
cast exhaust manifolds
24 INTAKE AND EXHAUST SYSTEMS
Automotive Technology, Fourth EditionJames Halderman
© 2011 Pearson Education, Inc.All Rights Reserved
MUFFLERSMUFFLERS
24 INTAKE AND EXHAUST SYSTEMS
Automotive Technology, Fourth EditionJames Halderman
© 2011 Pearson Education, Inc.All Rights Reserved
MufflersMufflers
• Purpose and Function– When the exhaust valve opens, it releases
a strong air pressure– The air pressure produces an explosion
24 INTAKE AND EXHAUST SYSTEMS
Automotive Technology, Fourth EditionJames Halderman
© 2011 Pearson Education, Inc.All Rights Reserved
MufflersMufflers
• Purpose and Function– Muffler catches bursts of high-pressure
exhaust in perforated tubes – Smoothing out bursts of pressure quiets
exhaust
24 INTAKE AND EXHAUST SYSTEMS
Automotive Technology, Fourth EditionJames Halderman
© 2011 Pearson Education, Inc.All Rights Reserved
Figure 24-20 Exhaust gases expand and cool as they travel through passages in the muffler.
24 INTAKE AND EXHAUST SYSTEMS
Automotive Technology, Fourth EditionJames Halderman
© 2011 Pearson Education, Inc.All Rights Reserved
MufflersMufflers
• Construction– Most mufflers have larger inlet diameter
than outlet diameter– Cooler exhaust is denser and requires less
volume
24 INTAKE AND EXHAUST SYSTEMS
Automotive Technology, Fourth EditionJames Halderman
© 2011 Pearson Education, Inc.All Rights Reserved
MufflersMufflers
• Construction– Resonators and catalytic converters also
functions as mufflers– Tailpipe releases exhaust gases away from
vehicle
24 INTAKE AND EXHAUST SYSTEMS
Automotive Technology, Fourth EditionJames Halderman
© 2011 Pearson Education, Inc.All Rights Reserved
MufflersMufflers
• Construction– Muffler and tailpipe are supported by
hangers– Hangers isolate exhaust noise from vehicle
24 INTAKE AND EXHAUST SYSTEMS
Automotive Technology, Fourth EditionJames Halderman
© 2011 Pearson Education, Inc.All Rights Reserved
MufflersMufflers
• Construction– Types of exhaust system hangers
• Rubberized fabric with metal ends• Rubber materials that look like rubber bands
?
24 INTAKE AND EXHAUST SYSTEMS
Automotive Technology, Fourth EditionJames Halderman
© 2011 Pearson Education, Inc.All Rights Reserved
Figure 24-21 A hole in the muffler allows condensed water to escape.
24 INTAKE AND EXHAUST SYSTEMS
Automotive Technology, Fourth EditionJames Halderman
© 2011 Pearson Education, Inc.All Rights Reserved
Figure 24-22 A high-performance aftermarket air filter often can increase airflow into the engine for more power.