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Engine Systems > 190202b Turbocharged Air Systems > Flashcards

190202b Turbocharged Air Systems Flashcards

0
Q

What’s the term used to describe engines that have a positive pressure forced into the cylinder by an exhaust driven centrifugal compressor

A

Turbocharged

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1
Q

There are five reasons why an engine maybe turbocharged. what are they

A

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

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2
Q

If the intake air increases in temperature on a turbocharged engine it will

A

Decrease engine power output

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3
Q

True or false a naturally aspirated engine will have a lower compression ratio than turbocharged

A

False

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4
Q

A turbocharger may be considered as a type of centrifugal air pump. True or false

A

True

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5
Q

Expanding hot engine exhaust gases act directly on what

A

They act on and directly drive the turbine wheel and shaft

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6
Q

Expanding engine exhaust gases turn the turbine wheel. what will automatically rotate as well

A

The compressor wheel

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7
Q

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

A

True

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8
Q

True or false. The turbine wheel and shaft and compressor wheel operate as a balanced assembly

A

True

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9
Q

What are four places oil may leak from the turbocharger

A

Oil supply line, oil drain line, turbine housing, compressor housing

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10
Q

What three components should be marked for alignment and/or balance purposes before they are removed from the turbocharger

A

Turbine housing, compressor housing, center housing

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11
Q

What is the best method used to test turbo boost pressure on a diesel engine

A

Load the engine to maximum horsepower

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12
Q

Is a possible reason for low turbo boost pressure on a diesel engine,the fuel injection system

A

Yes

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13
Q

Cooling the hot compressed air leaving the turbocharger before it gets to the engine cylinders with aftercoolers and intercoolers does what

A

Improves engine performance increases fuel economy and reduces exhaust emissions

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14
Q

What are the two air to air intercoolers

A

Charge air cooler’s and air to air after coolers, ATAAC

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15
Q

What’s the name for air to coolant

A

Aftercoolers

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16
Q

In what environment is the air to air intercooler generally the most effective

A

If the cooler is exposed to a moving airstream

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17
Q

The air to coolant aftercooler may be considered more effective when used where

A

In a stationary application

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18
Q

Which type of air cooler would generally be considered the easiest to test for leaks

A

The air to air cooler is often the easiest to access and test

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19
Q

How does the wastegate control the maximum turbo boost

A

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

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20
Q

Can the coolant used in an aftercooler be able to enter the combustion chamber if a leak occures in the cooler core.

A

Yes

21
Q

If boost pressure in an aftercooler system is greater than the cooling system pressure, can air into the cooling system

A

Yes

22
Q

What would be the major problem if a broken sensing line between the wastegate actuator in the intake manifold occurred

A

Intake manifold turbo boost and speed would be unregulated

23
Q

How does a VDT control turbo boost and turbine speed

there are two types of VDT

A

A VDT varies the exhaust gas flow to the turbine wheel to control turbo boost and turbine speed

24
Q

What are the two types of variable displacement turbochargers

A

Sliding nozzle vane and pivoting nozzle vane

25
Q

The VDT turbo works in conjunction with which exhaust emission control system

A

The exhaust gas recirculation emission system. EGR

26
Q

Some manufactures identify the air leaving the compressor housing as _________.

A

Charge air flow

27
Q

The turbo is assembled in the _________ order of disassembly.

A

reverse

28
Q

What could result if the wrong turbo is installed on a engine __________.

A

low power

29
Q

Causes of low boost pressure and low engine power can be caused by:

A

worn engine parts
faulty fuel injection system
leaking intake air hose
restricted air to air cooler

30
Q

Maximum temp rise between the ambient air and the engine inlet air should only _______ in the turbo charger.

A

15C (30F)

31
Q

Why is the compressor housing constructed of aluminum?

A
  1. light

2. heat transfer

32
Q

Turbine rpm can be over ___________.

A

100,000 RPM

33
Q

Turbine housing are usually constructed of:

A

cast iron

34
Q

Turbo charger components include?

A

Turbine housing, turbine shaft and wheel assembly, compressor housing and compressor wheel

35
Q

Turbo charged engine is correctly designed , the power output may be ___________ or more then a comparable sized naturally aspirated engine.

A

50%

36
Q

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

A

3 to 5 minutes

3 to 5 minutes

37
Q

The VDT has two designs:

variable displacement turbo

A

sliding nozzle vane

pivoting nozzle vane

39
Q

Intercooler design maybe able reduce the intake air temperature of 135-160C (275- 325F) to approximately ________

A

43C (110F)

40
Q

What the two ways to cool inlet air

A

intercoolers (air to air)

aftercoolers (air to coolant)

41
Q

When a turbo charged engine is correctly designed the output may be _____% or more of a comparable sized naturally aspirated engine?

A

50%

42
Q

Turbocharger is often referred to as a ________ air pump.

A

centrifugal pump

43
Q

Turbocharger components include?

A

turbine housing and wheel

compressor housing and wheel

44
Q

Turbine housing are usually constructed of?

A

Cast-iron

45
Q

Turbine wheel speed could be well over _________ RPM.

A

100,000 RPM

46
Q

Compressor housing is usually constructed of aluminum, why?

A

heat transfer (light weight)

47
Q

Maximum temperature rise between ambient air and the engine inlet air should only __________ in the turbocharger.

A

15 C (30 F)

48
Q

Some causes for low boost pressure along with low engine power are?

A

worn engine parts
faulty injection system
leaking or restricted air to air cooler

49
Q

What will be the result if the wrong turbo charger is on the engine.

A

low power could result

50
Q

Some manufacture identify the air leaving the compressor housing as __________.

A

charge air flow

Engine Systems (4 decks)

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