Question 1

What is a typical compression pressure achieved in a current highway truck diesel engine?

Accepted Answer

A)  150 PSI 
B)  350 PSI 
C)  600 PSI 
D)  1200 PSI 
A)  150 PSI 
B)  350 PSI 
C)  600 PSI 
D)  1200 PSI C

Question 2

How many times does any one piston change direction during one complete diesel cycle?

Accepted Answer

A)  two times 
B)  four times 
C)  six times 
D)  eight times 
A)  two times 
B)  four times 
C)  six times 
D)  eight times B

Question 3

Technician A says that valve overlap takes place as the piston completes its compression stroke. Technician B says that cylinder scavenging takes place at valve overlap. Who is correct?

Accepted Answer

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

Question 4

Technician A says that turbochargers are used to aspirate the cylinders on most commercial diesel engines. Technician B says that turbochargers can help expel end gas during valve overlap. Who is correct?

Accepted Answer

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

Question 5

What would be the highest thermal efficiency achievable in a current truck diesel engine?

Accepted Answer

A)  10% 
B)  25% 
C)  40% 
D)  60% 
A)  10% 
B)  25% 
C)  40% 
D)  60%

Question 6

What is another name for the power stroke in the engine cycle?

Accepted Answer

A)  Compression stroke 
B)  Scavenging stroke 
C)  Gas blowdown 
D)  Expansion stroke 
A)  Compression stroke 
B)  Scavenging stroke 
C)  Gas blowdown 
D)  Expansion stroke

Question 7

What term is used to describe the tendency of an object in motion, to want to stay in motion?

Accepted Answer

A)  static friction 
B)  dynamic friction 
C)  kinetic energy 
D)  inertia 
A)  static friction 
B)  dynamic friction 
C)  kinetic energy 
D)  inertia

Question 8

Convert the specified displacement of a MaxxForce DT engine with a displacement of 466 cubic inches into liters:

Accepted Answer

A)  7.6 liters 
B)  8.2 liters 
C)  8.9 liters 
D)  9.4 liters 
A)  7.6 liters 
B)  8.2 liters 
C)  8.9 liters 
D)  9.4 liters

Question 9

Which of the following is another way of saying kinetic energy?

Accepted Answer

A)  inertia 
B)  energy of motion 
C)  heat energy 
D)  thermal efficiency 
A)  inertia 
B)  energy of motion 
C)  heat energy 
D)  thermal efficiency

Question 10

The four strokes of the diesel cycle take place over:

Accepted Answer

A)  90 degrees rotation 
B)  180 degrees rotation 
C)  360 degrees rotation 
D)  720 degrees rotation 
A)  90 degrees rotation 
B)  180 degrees rotation 
C)  360 degrees rotation 
D)  720 degrees rotation

Question 11

When exactly does the gas blowdown phase occur?

Accepted Answer

A)  when exhaust valve first opens 
B)  at BDC during the exhaust stroke 
C)  close to TDC on the exhaust stroke 
D)  during cylinder scavenging 
A)  when exhaust valve first opens 
B)  at BDC during the exhaust stroke 
C)  close to TDC on the exhaust stroke 
D)  during cylinder scavenging

Question 12

A Cummins X-15 has a total engine displacement of 15 liters. Convert this into cubic inches:

Accepted Answer

A)  893 cubic inches 
B)  915 cubic inches 
C)  943 cubic inches 
D)  997 cubic inches 
A)  893 cubic inches 
B)  915 cubic inches 
C)  943 cubic inches 
D)  997 cubic inches

Question 13

Technician A says that diesel fuel is composed of roughly 85% carbon. Technician B says that diesel fuels commonly contain around 15% hydrogen. Who is correct?

Accepted Answer

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

Question 14

What is the term used to describe the relationship between the work performed by a piston during the compression stroke, and the work received by it during the power stroke?

Accepted Answer

A)  brake horsepower (BHP) 
B)  torque gain 
C)  mean effective pressure (MEP) 
D)  constant volume cycle 
A)  brake horsepower (BHP) 
B)  torque gain 
C)  mean effective pressure (MEP) 
D)  constant volume cycle

Question 15

Which of the following is true of the term clearance volume?

Accepted Answer

A)  Cylinder volume with piston at TDC 
B)  Cylinder volume with piston at BDC 
C)  Cylinder volume with piston removed 
D)  Volume of a pre-combustion chamber 
A)  Cylinder volume with piston at TDC 
B)  Cylinder volume with piston at BDC 
C)  Cylinder volume with piston removed 
D)  Volume of a pre-combustion chamber

Question 16

What do you do to convert liters into cubic inches?

Accepted Answer

A)  multiply by 61 
B)  divide by 61 
C)  multiply by 5/8 
D)  multiply by 10 
A)  multiply by 61 
B)  divide by 61 
C)  multiply by 5/8 
D)  multiply by 10

Question 17

Which of the following terms is used to describe the overall breathing efficiency of an engine?

Accepted Answer

A)  scavenging 
B)  thermal efficiency 
C)  volumetric efficiency 
D)  combustion efficiency 
A)  scavenging 
B)  thermal efficiency 
C)  volumetric efficiency 
D)  combustion efficiency

Question 18

If a diesel engine has a thermal efficiency of 35%, what percentage of the heat energy of the fuel is discharged as rejected heat?

Accepted Answer

A)  35% 
B)  65% 
C)  Half of 35% 
D)  Half of 65% 
A)  35% 
B)  65% 
C)  Half of 35% 
D)  Half of 65%

Question 19

Technician A says that the greater the temperature difference between the cylinder temperature on the compression stroke and the firepoint of the fuel, the longer the ignition lag. Technician B says that a typical diesel fuel formulated for on highway use has a firepoint of about 250 degrees Celsius (482 degrees Fahrenheit). Who is correct?

Accepted Answer

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

Question 20

If an engine is described as naturally aspirated, which of the following should be true?

Accepted Answer

A)  Constant geometry turbocharger is used 
B)  Variable geometry turbocharge is used 
C)  Roots blower is used 
D)  There is no manifold boost 
A)  Constant geometry turbocharger is used 
B)  Variable geometry turbocharge is used 
C)  Roots blower is used 
D)  There is no manifold boost

Exam 4: Engine Basics

What is a typical compression pressure achieved in a current highway truck diesel engine?

How many times does any one piston change direction during one complete diesel cycle?

Technician A says that valve overlap takes place as the piston completes its compression stroke. Technician B says that cylinder scavenging takes place at valve overlap. Who is correct?

Technician A says that turbochargers are used to aspirate the cylinders on most commercial diesel engines. Technician B says that turbochargers can help expel end gas during valve overlap. Who is correct?

What would be the highest thermal efficiency achievable in a current truck diesel engine?

What is another name for the power stroke in the engine cycle?

What term is used to describe the tendency of an object in motion, to want to stay in motion?

Convert the specified displacement of a MaxxForce DT engine with a displacement of 466 cubic inches into liters:

Which of the following is another way of saying kinetic energy?

The four strokes of the diesel cycle take place over:

When exactly does the gas blowdown phase occur?

A Cummins X-15 has a total engine displacement of 15 liters. Convert this into cubic inches:

Technician A says that diesel fuel is composed of roughly 85% carbon. Technician B says that diesel fuels commonly contain around 15% hydrogen. Who is correct?

What is the term used to describe the relationship between the work performed by a piston during the compression stroke, and the work received by it during the power stroke?

Which of the following is true of the term clearance volume?

What do you do to convert liters into cubic inches?

Which of the following terms is used to describe the overall breathing efficiency of an engine?

If a diesel engine has a thermal efficiency of 35%, what percentage of the heat energy of the fuel is discharged as rejected heat?

If an engine is described as naturally aspirated, which of the following should be true?

Introduction

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History of the Heat Engine

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