Deck 2: Introduction to Diesel Engines

Question 1

In a four stroke cycle diesel engine, when are the intake valves open?

A) During all of the intake stroke and final part of the exhaust stroke.
B) During the intake stroke and final part of the power stroke.
C) For only part of the intake stroke.
D) Only during the intake stroke.

Answer 1

A

Question 2

During valve overlap what takes place?

A) The compression and power strokes.
B) Maximum compression pressure.
C) Compression ignition and fuel injection.
D) Expelling of end gases and cooling of the piston crown.

Answer 2

D

Question 3

At what location during the power stroke does the crank throw provide maximum mechanical leverage?

A) Whenever the cylinder pressure is maximum.
B) Whenever the compression pressure is maximum.
C) From 15 degrees ATDC to 90 degrees ATDC.
D) When the throw is positioned 90 degrees ATDC.

Answer 3

D

Question 4

Which of the following terms best describes a diesel engine used in a light duty pick-up truck intended for use as a work truck?

A) On-highway vocational automotive diesels.
B) Off highway light duty diesels.
C) Spark ignition (SI) light duty diesels.
D) Light duty passenger engines.

Question 5

Which statement best describes Mean Effective Pressure (MEP)

A) Average pressure during engine braking.
B) Average of cylinder pressure and throw angle torque.
C) Peak combustion pressure minus peak compression pressure.
D) Turbochargers peak pressure minus the combustion peak pressure.

Question 6

Why are most diesel engines turbo-boosted?

A) To increase the compression ratio.
B) Turbo-boosting reduces the required clearance volume
C) To increase the volumetric efficiency of the engine.
D) To increase the fuel's heat energy potential.

Question 7

What are the four phases of the exhaust process?

A) Pressure release, Gas Blowdown, Cylinder Cooling, Valve Overlap.
B) Cylinder pressure, Valve Overlap, Inertial, Scavenging.
C) Pressure Differential, Displacement, Scavenging, Recirculation.
D) Pressure Differential, Inertial, Displacement, Scavenging.

Question 8

In a four stroke cycle diesel engine, when is fuel injected into the cylinder?

A) At the end of the compression stroke and the beginning of the power stroke.
B) During the compression and exhaust strokes .
C) Only when the piston is at TDC in the compression stroke.
D) Only during the power stroke.

Question 9

How do you define diesel engine breathing efficiency?

A) Total volume of exhaust gases as a percentage of engine displacement.
B) Ratio of the maximum compression pressure to maximum cylinder pressure expressed as a percentage.
C) Total air volume required to maintain any given engine RPM.
D) Actual volume of air taken in during the intake stroke versus cylinder swept volume.

Question 10

What class of diesel engines recently became regulated by the EPA (Environmental Protection Agency)?

A) All light duty diesel engines with less than 8 liters displacement.
B) Light duty diesel engines used only as work vehicles.
C) The current lineup of Detroit's pickup truck work diesels.
D) Off-highway light duty diesels.

Question 11

What types of fuels can be used in diesel engines?

A) Any fuel that has a heat energy rating higher than gasoline.
B) Hydrocarbon fuels.
C) The type of fuel isn't important as long as it has a low fire point.
D) Only petroleum based diesel fuels.

Question 12

Technician A states all onhighway diesel engines sold in North America must meet or exceed EPA emission standards. Technician B states all current highway diesel engines must be computer controlled and have exhaust gas aftertreatment devices. Which technician is correct?

A) Technician A only.
B) Technician B only.
C) Both A and B.
D) Neither A nor B.

Question 13

Which of the following is true of a fuel's fire point and its cetane number.

A) Fire point has no bearing on Cetane rating.
B) Cetane rating increases as its fire point decreases.
C) Cetane rating does not influence fire point
D) Cetane rating increases as the fire point increases.

Question 14

What device on the engine is responsible for manifold-boost?

A) Piston
B) Turbocharger
C) Exhaust gas recirculation system
D) Manifold

Question 15

What engine system attempts to manage the cylinder pressure in electronically controlled engines?

A) MEP system.
B) Turbocharger.
C) Fuel Management System.
D) Engine Cooling Circuit.

Question 16

What two values combine to determine total cylinder volume?

A) Bore diameter and the stroke length.
B) Clearance volume plus swept volume.
C) Cylinder height minus the clearance volume.
D) Engine displacement divided by the number of cylinders.

Question 17

What engine management strategy alters the MEP equation?

A) Engine braking and variable valve timing.
B) Direct fuel injection and ignition delay.
C) Valve overlap and ignition temperature control.
D) Exhaust gas recirculation and manifold boost.

Question 18

Why is the term CI commonly used as an acronym for diesel engines?

A) All diesel engines use this fuel ignition method.
B) Diesel engines compress a rich air/fuel mixture before igniting it with glow plugs.
C) Older spark ignited diesel engines are no longer manufactured and CI is the new standard.
D) It describes the type of emissions controls used on diesels.

Question 19

Why do most diesel engines tend to be undersquare?

A) To produce high compression ratios.
B) Turbocharging is easier to accomplish in undersquare engines.
C) To increase thermal efficiency therefore reducing rejected heat.
D) It cost less to make undersquared engines.

Question 20

What two strokes have minimal effect when calculating the Mean Effective Pressure (MEP).

A) Intake and exhaust strokes.
B) Intake, compression and exhaust stroke.
C) Exhaust, power and intake strokes.
D) Intake and power strokes.

Question 21

Technician A states a typical electronically controlled CI engine has thermal efficiency exceeding 40%. Technician B states 90% of the heat created from burning fuel in a CI engine ends up as rejected heat. Which technician is correct?

A) Technician A only.
B) Technician B only.
C) Both A and B.
D) Neither A nor B.