Piston Engine

Question 1

What are the 2 components of “mixture”

Answer 1

1. Fuel
2. Air

Burned in a confined space

Question 2

What is the basic 2 elements of how a piston engine works

Answer 2

1. Mixture burned forces MECHANICAL movement
2. Mechanical movement transformed into ROTARY motion

Question 3

A reciprocating engine is made up of what 4 parts

Answer 3

1. Cylinders
2. Camshaft
3. Crankcase
4. Accessory Housing

Cylinders Can crank accessively

Question 4

What 3 components are located in the cylinder

Answer 4

1. Intake/Exhaust valves
2. Spark Plugs
3. Pistons

Question 5

What is the primary responsibility of the camshaft

Answer 5

Ensure intake/exhaust valves open/close at correct time

Question 6

What is the primary responsibility of the crankshaft

Answer 6

Tranform up/down piston motion into rotary motion

Question 7

What are the 4 strokes of the Otto cycle

Answer 7

1. Suck (Intake)
2. Squeeze (Compression)
3. Bang (Power)
4. Blow (Exhaust)

Question 8

At what stage of the otto cycle does the intake valve open.
What position is the piston in

Answer 8

1. Intake / Suck
2. Top Dead Centre (TDC)

Question 9

At what stage of the otto cycle does the intake valve close
What position is the piston in

Answer 9

1. Intake / Suck
2. Bottom Dead centre (BDC)

Question 10

During the intake stroke, what is the piston moved down by and what happens as a result

Answer 10

1. Crankshaft rotation moves piston down
2. Sucks in fuel & air mixture

Question 11

What direction is the piston moving during the compression cycle

Answer 11

UP

Question 12

What is a typical compression ratio of a lycoming piston engine

Answer 12

7:1

Question 13

What is the definition of a compression ration

Answer 13

The amount the mixture is compressed by when taking the complete volume of the cylinder into account

Complete volume of cylinder when piston BDC
Compressed volume of cylinder when piston TDC

Question 14

A higher compression ratio makes the engine MORE or LESS efficient

Answer 14

MORE

Question 15

What direction is the piston moving during the power cycle

Answer 15

DOWN

Forced by expanding of burning mixture

Question 16

What position is the piston in when the power stroke completes

Answer 16

Bottom Dead Centre
(BDC)

Question 17

What part of the otto cycle will the exhaust valve open

Answer 17

EXHAUST

Question 18

What position will the piston be in when the exhaust valve closes

Answer 18

Top Dead Centre
(TDC)

Question 19

How many revolutions of the crank shaft occur during a 4 stroke process

Answer 19

2

Question 20

When the spark typically gets produced, what position is the piston

Normal operation, and not during start up

Answer 20

20॰ advanced of TDC

Question 21

Why are valve timings adjusted on a 4 stroke engine

Answer 21

IMPROVE EFFICIENCY

Question 22

Modified 4 stroke cycle

When will the exhaust close (what position is the piston)
During which cycle

Answer 22

1. 20॰ after TDC
2. End of EXHAUST cycle/During INDUCTION cycle

Question 23

Modified 4 stroke cycle

When will the inlet valve open (what position is the piston)
During which cycle

Answer 23

1. 15॰ before of TDC
2. During EXHAUST / Beginning of INDUCTION

Question 24

Modified 4 stroke cycle

When will the inlet close (what position is the piston)

Answer 24

75॰ after BDC

Question 25

# modified 4 stroke cycle When will the spark occur (what position is the piston) During which cycle

Answer 25

1. 25॰ before TDC 2. End of COMPRESSION / Beginning of POWER

Question 26

# Modified 4 stroke cycle When will the exhaust outlet open (what position is the piston) During which cycle

Answer 26

1. 70॰ before BDC 2. End of POWER / Beginning of EXHAUST

Question 27

What is the definition of pre-ignition

Answer 27

Fuel/Air mixture igniting too early

Question 28

What are 4 common causes of pre ignition

Answer 28

1. Timing 2. Hot Spot 3. Octane 4. Pressure ## Footnote 1. Incorrect enging timing 2. Engine Hot-Spots 3. Incorrect fuel octane rating (too low) 4. High cylinder pressure

Question 29

What are 2 symptoms to identify pre-ignition

Answer 29

1. "Knocking" 2. High Cylinder Temperature

Question 30

What temperature and above would indicate high cylinder temperature

Answer 30

above 400॰ F