190202b Turbocharged Air Systems Flashcards
What’s the term used to describe engines that have a positive pressure forced into the cylinder by an exhaust driven centrifugal compressor
Turbocharged
There are five reasons why an engine maybe turbocharged. what are they
Offsets lost performance at higher altitudes, increases power output without significant engine and weight increase, increases power output without significant engine size increase, compensates for more variation in load demands, reduces exhaust emissions and increases feel economy
If the intake air increases in temperature on a turbocharged engine it will
Decrease engine power output
True or false a naturally aspirated engine will have a lower compression ratio than turbocharged
False
A turbocharger may be considered as a type of centrifugal air pump. True or false
True
Expanding hot engine exhaust gases act directly on what
They act on and directly drive the turbine wheel and shaft
Expanding engine exhaust gases turn the turbine wheel. what will automatically rotate as well
The compressor wheel
True or false. Heat absorbed by the turbine housing and turbine wheel and shaft assembly will be transferred to the oil passing through the turbocharger
True
True or false. The turbine wheel and shaft and compressor wheel operate as a balanced assembly
True
What are four places oil may leak from the turbocharger
Oil supply line, oil drain line, turbine housing, compressor housing
What three components should be marked for alignment and/or balance purposes before they are removed from the turbocharger
Turbine housing, compressor housing, center housing
What is the best method used to test turbo boost pressure on a diesel engine
Load the engine to maximum horsepower
Is a possible reason for low turbo boost pressure on a diesel engine,the fuel injection system
Yes
Cooling the hot compressed air leaving the turbocharger before it gets to the engine cylinders with aftercoolers and intercoolers does what
Improves engine performance increases fuel economy and reduces exhaust emissions
What are the two air to air intercoolers
Charge air cooler’s and air to air after coolers, ATAAC
What’s the name for air to coolant
Aftercoolers
In what environment is the air to air intercooler generally the most effective
If the cooler is exposed to a moving airstream
The air to coolant aftercooler may be considered more effective when used where
In a stationary application
Which type of air cooler would generally be considered the easiest to test for leaks
The air to air cooler is often the easiest to access and test
How does the wastegate control the maximum turbo boost
The wastegate system on a turbo senses turbo boost pressure and at a predetermined amount the waste-gate valve opens and allows exhaust gas to bypass the turbine wheel. this slows down the turbine and limits maximum boost pressure
Can the coolant used in an aftercooler be able to enter the combustion chamber if a leak occures in the cooler core.
Yes
If boost pressure in an aftercooler system is greater than the cooling system pressure, can air into the cooling system
Yes
What would be the major problem if a broken sensing line between the wastegate actuator in the intake manifold occurred
Intake manifold turbo boost and speed would be unregulated
How does a VDT control turbo boost and turbine speed
there are two types of VDT
A VDT varies the exhaust gas flow to the turbine wheel to control turbo boost and turbine speed
What are the two types of variable displacement turbochargers
Sliding nozzle vane and pivoting nozzle vane
The VDT turbo works in conjunction with which exhaust emission control system
The exhaust gas recirculation emission system. EGR
Some manufactures identify the air leaving the compressor housing as _________.
Charge air flow
The turbo is assembled in the _________ order of disassembly.
reverse
What could result if the wrong turbo is installed on a engine __________.
low power
Causes of low boost pressure and low engine power can be caused by:
worn engine parts
faulty fuel injection system
leaking intake air hose
restricted air to air cooler
Maximum temp rise between the ambient air and the engine inlet air should only _______ in the turbo charger.
15C (30F)
Why is the compressor housing constructed of aluminum?
- light
2. heat transfer
Turbine rpm can be over ___________.
100,000 RPM
Turbine housing are usually constructed of:
cast iron
Turbo charger components include?
Turbine housing, turbine shaft and wheel assembly, compressor housing and compressor wheel
Turbo charged engine is correctly designed , the power output may be ___________ or more then a comparable sized naturally aspirated engine.
50%
Operator should allow the engine to run at half speed under no load for _______ to________ .
Then the operator should allow the engine to idle _______ to________ before shutting down
3 to 5 minutes
3 to 5 minutes
The VDT has two designs:
variable displacement turbo
sliding nozzle vane
pivoting nozzle vane
Intercooler design maybe able reduce the intake air temperature of 135-160C (275- 325F) to approximately ________
43C (110F)
What the two ways to cool inlet air
intercoolers (air to air)
aftercoolers (air to coolant)
When a turbo charged engine is correctly designed the output may be _____% or more of a comparable sized naturally aspirated engine?
50%
Turbocharger is often referred to as a ________ air pump.
centrifugal pump
Turbocharger components include?
turbine housing and wheel
compressor housing and wheel
Turbine housing are usually constructed of?
Cast-iron
Turbine wheel speed could be well over _________ RPM.
100,000 RPM
Compressor housing is usually constructed of aluminum, why?
heat transfer (light weight)
Maximum temperature rise between ambient air and the engine inlet air should only __________ in the turbocharger.
15 C (30 F)
Some causes for low boost pressure along with low engine power are?
worn engine parts
faulty injection system
leaking or restricted air to air cooler
What will be the result if the wrong turbo charger is on the engine.
low power could result
Some manufacture identify the air leaving the compressor housing as __________.
charge air flow
