202B - Turbocharged Air Systems Flashcards

1
Q

What five benefits do turbocharged engines serve?

A
  • Can operate at higher altitudes
  • Increases power output without increasing weight
  • Increases power without increasing size
  • Compensates for varying load demands
  • Reduces exhaust gas emissions

202b pg. 3

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2
Q

What must be used to cool the intake airflow on a turbocharged engine?

A

Aftercoolers or intercoolers

202b pg. 3

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3
Q

Compared to a naturally aspirated engine, a turbocharged engine has what differences incorporated into its design?

A
  • Lower compression ratio
  • Changed camshaft and valve timing
  • Retarded injection timing
  • Increased fuel injector and/or pump size
  • Crankcase often vented to air intake, but could be vented to atmosphere

202b pg. 4

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4
Q

The turbine is what side of a turbocharger?

A

Exhaust side.

202b pg. 6

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5
Q

The compressor is what side of the turbocharger?

A

Intake air side

202b pg. 8

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6
Q

The turbine housing on a turbocharger is made of what?

A

Heavy cast iron

202b pg. 6

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7
Q

How fast could the turbine wheel on a turbocharger spin?

A

Could be well over 100000 rpm

202b pg. 7

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8
Q

In a turbocharger, what diverts some exhaust gases away from the turbine wheel as a method of controlling boost?

A

Wastegate

202b pg. 7

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9
Q

What is the turbocharger diffuser plate?

A

Angled vanes that increase the efficiency of the turbocharger by precisely and smoothly directing the boost air into the intake manifold.

202b pg. 8

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10
Q

What are some engines equipped with to temporarily supply the turbo with oil until the engine oil pump is fully operational?

A

Manual or electric oil pumps

202b pg. 8

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11
Q

What is the turbocharger wind back seal?

A

Threads on the shaft that acts as an oil seal.

202b pg. 9

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12
Q

On a turbocharger, sealing between the compressor housing and centre housing is often done by using: (2)

A
  • O-rings
  • RTV

202b pg. 9

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13
Q

What is the maximum restriction for the air induction system and exhaust system?

A

Air induction: 25 inches of water
Exhaust: 3 inches of mercury

202b pg. 12

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14
Q

If the engine exhaust has a blue colour, what it the likely cause?

A

Burning oil

202b pg. 16

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15
Q

If a cool-down period is not used with a turbocharger, the oil burns and ______ on the bearing surfaces?

A

Cokes

202b pg. 18

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16
Q

When checking radial play of turbine and compressor wheels with feeler blades, how many measurements should be taken?

A

Three measurements equally spaced around the wheel, between the wheel and housing.

202b pg. 19

17
Q

When installing a turbo, what should be done before starting the engine to ensure that the turbo will not run dry of oil?

A

Pre-lube the turbo before connecting the oil line.

202b pg. 23

18
Q

How should a turbocharged engine be properly shut down to prolong the life of the turbo?

A

1) Run engine at half speed for 3-5 minutes
2) Run engine at idle for 3-5 minutes

202b pg. 24

19
Q

What should be done while transporting turbocharged equipment to prevent damage to the turbo?

A

Cover the end of the exhaust pipe to prevent air from spinning the turbo dry

202b pg. 24

20
Q

Is an aftercooler air-to-air or air-to-coolant?

A

Air-to-coolant

202b pg. 27

21
Q

Is an intercooler air-to-air or air-to-coolant?

A

Air-to-air

202b pg. 26

22
Q

On what types of equipment are aftercoolers generally used on?

A

Stationary, off-road, or slow moving equipment where there is not a lot of airflow.

23
Q

What two problems could result from a leak in an air-to-air intercooler?

A
  • Lost turbocharged pressure
  • Dust could enter the engine

202b pg. 28

24
Q

How does a wastegate control turbo boost pressure?

A

Senses boost pressure and allows exhaust gasses to bypass the turbine wheel.

Sets the max boost pressure and prevents turbo over-speed.

202b pg. 31

25
Q

What would result from a wastegate valve stuck open?

A

Low power complaint

202b pg. 33

26
Q

What would result from a wastegate stuck closed?

A

Unregulated turbo speed which could cause damage

202b pg. 33

27
Q

A sliding nozzle vane type turbo is what type of turbo?

A

Variable displacement turbo

202b pg. 34

28
Q

How does a variable displacement turbocharger regulate boost pressure?

A

By extending or retracting the nozzle to cover and uncover the fins.

Extending the nozzle = more boost and back pressure
Retracting the nozzle = less boost and back pressure

202b pg. 35

29
Q

A pivoting nozzle vane turbo is what type of turbo?

A

Variable geometry turbo

30
Q

What precautions should be observed when servicing turbochargers? (7)

A
  • Pre-lube the turbo
  • Cap all openings to prevent dirt entry
  • Check radial and axial play
  • Check turbine & compressor wheels spin freely
  • Align clocking pins or marks for proper orientation
  • Use the proper sealing compound
  • Torque and use new lockplates/lockwire

202b pg. 22

31
Q

With ambient air temp is at 29C, the boosted air will increase in temperature to approximately:

A

149C

202b pg. 3

32
Q

What is a turbo diffuser?

A

A plate in the compressor side that uses angled vanes to increase the efficiency of the turbo by precisely and smoothly directing the boost air into the intake manifold.

202b pg. 8