Piston Engine Flashcards
What are the 2 components of “mixture”
- Fuel
- Air
Burned in a confined space
What is the basic 2 elements of how a piston engine works
- Mixture burned forces MECHANICAL movement
- Mechanical movement transformed into ROTARY motion
A reciprocating engine is made up of what 4 parts
- Cylinders
- Camshaft
- Crankcase
- Accessory Housing
Cylinders Can crank accessively
What 3 components are located in the cylinder
- Intake/Exhaust valves
- Spark Plugs
- Pistons
What is the primary responsibility of the camshaft
Ensure intake/exhaust valves open/close at correct time
What is the primary responsibility of the crankshaft
Tranform up/down piston motion into rotary motion
What are the 4 strokes of the Otto cycle
- Suck (Intake)
- Squeeze (Compression)
- Bang (Power)
- Blow (Exhaust)
At what stage of the otto cycle does the intake valve open.
What position is the piston in
- Intake / Suck
- Top Dead Centre (TDC)
At what stage of the otto cycle does the intake valve close
What position is the piston in
- Intake / Suck
- Bottom Dead centre (BDC)
During the intake stroke, what is the piston moved down by and what happens as a result
- Crankshaft rotation moves piston down
- Sucks in fuel & air mixture
What direction is the piston moving during the compression cycle
UP
What is a typical compression ratio of a lycoming piston engine
7:1
What is the definition of a compression ration
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
A higher compression ratio makes the engine MORE or LESS efficient
MORE
What direction is the piston moving during the power cycle
DOWN
Forced by expanding of burning mixture
What position is the piston in when the power stroke completes
Bottom Dead Centre
(BDC)
What part of the otto cycle will the exhaust valve open
EXHAUST
What position will the piston be in when the exhaust valve closes
Top Dead Centre
(TDC)
How many revolutions of the crank shaft occur during a 4 stroke process
2
When the spark typically gets produced, what position is the piston
Normal operation, and not during start up
20॰ advanced of TDC
Why are valve timings adjusted on a 4 stroke engine
IMPROVE EFFICIENCY
Modified 4 stroke cycle
When will the exhaust close (what position is the piston)
During which cycle
- 20॰ after TDC
- End of EXHAUST cycle/During INDUCTION cycle
Modified 4 stroke cycle
When will the inlet valve open (what position is the piston)
During which cycle
- 15॰ before of TDC
- During EXHAUST / Beginning of INDUCTION
Modified 4 stroke cycle
When will the inlet close (what position is the piston)
75॰ after BDC
modified 4 stroke cycle
When will the spark occur (what position is the piston)
During which cycle
- 25॰ before TDC
- End of COMPRESSION / Beginning of POWER
Modified 4 stroke cycle
When will the exhaust outlet open (what position is the piston)
During which cycle
- 70॰ before BDC
- End of POWER / Beginning of EXHAUST
What is the definition of pre-ignition
Fuel/Air mixture igniting too early
What are 4 common causes of pre ignition
- Timing
- Hot Spot
- Octane
- Pressure
- Incorrect enging timing
- Engine Hot-Spots
- Incorrect fuel octane rating (too low)
- High cylinder pressure
What are 2 symptoms to identify pre-ignition
- “Knocking”
- High Cylinder Temperature
What temperature and above would indicate high cylinder temperature
above 400॰ F
