201A - Engine Fundamentals

Question 1

When did the development and construction of the first internal combustion engine start?

Answer 1

In the 1700’s

201A pg. 2

Question 2

Who defined the four-stroke cycle?
When did this take place?

Answer 2

Beau De Rochas in 1862

201A pg. 2

Question 3

Who built the first successful four-stroke compression ignition engine?
When?

Answer 3

Dr. Rudolf Diesel in 1895

201A pg. 3

Question 4

What year did EGR systems begin to be used to meet Tier 2 regulations?

Answer 4

2004

201A pg. 4

Question 5

What happened in 2007 for exhaust emission regulations?

Answer 5

Tier 3
DPF & ULSD of 15ppm

201A pg. 4

Question 6

What happened in 2010 for exhaust emission regulations?

Answer 6

Tier 4
SCR & DEF

201A pg. 4

Question 7

What is the stroke of a piston?

Answer 7

Distance the piston moved from TDC to BDC. Determined by the throw of the crankshaft (2x the throw).

201A pg. 9

Question 8

What is piston displacement?

Answer 8

The swept volume of a single cylinder.

Displacement = cylinder area * stroke

201A pg. 10

Question 9

How is engine displacement calculated?

Answer 9

The swept volume of all cylinders. Directly related to the amount of power an engine can produce.

Disp = piston disp. * #cylinders

201A pg. 10

Question 10

What is compression ratio in an engine cylinder?

Answer 10

Ratio comparing the volume above the piston at BDC to the volume above the piston at TDC.

CR = (Piston Displacement - Clearance Volume) / Clearance Volume

201A pg. 11

Question 11

What is volumetric efficiency?

Answer 11

The comparison between the actual amount of air taken into a cylinder during the intake stroke divided by the actual cylinder volume.

A naturally aspirated engine is approx. 85% VE

Reduced by engine design:
- Intake manifold design
- Valve size
- Valve timing
- Plugged air filter

Increased by:
- Turbo

201A pg. 12

Question 12

How thermal efficient is an internal combustion engine?

Answer 12

Approximately 36%

Remaining:
7% Overcome friction
27% Cooling system
30% Exhaust system

201A pg. 12

Question 13

What is indicated horsepower?

Answer 13

Theoretical amount of horsepower

201A pg. 13

Question 14

What is frictional horsepower?

Answer 14

Horsepower lost to overcome friction

201A pg. 13

Question 15

What is brake horsepower?

Answer 15

The Usable horsepower measured at the flywheel.

bhp = ihp - fph

201A pg. 13

Question 16

What is mechanical efficiency?

Answer 16

The comparison of brake horsepower and indicated horsepower, represented as a percentage.

ME = bhp/ihp *100

201A pg. 13

Question 17

Does a two-stroke engine have a shorter or longer effective power stroke?

Answer 17

Two-stroke has a shorter effective power stroke

Question 18

What is scavenging?

Answer 18

The removal of exhaust gasses from the cylinder.

Two-strokes use a positive displacement blower.

Four-strokes use valve overlap.

201A pg. 21

Question 19

What is the effective power stroke of a four-stroke engine?

Answer 19

120-140 degrees of crankshaft rotation.

(Longer than a two-stroke power stroke)

201A pg. 24

Question 20

What is the compression ratio of a four-stroke diesel engine?

Answer 20

14:1 - 23:1

(Gas engine: 8:1 - 9:1)

201A pg. 26