Engine Terms Flashcards
1
Q
What does TDC mean?
A
- top dead centre
- upper most limit of the piston
2
Q
what does BDC mean?
A
- bottom dead centre
- lowest limit of piston travel
3
Q
What does bore mean?
A
- internal diameter of a cylinder
4
Q
What does stroke mean?
A
- the distance between TDC AND BDC
5
Q
What does swept volume mean?
A
- volume of cylinder between TDC and BDC
6
Q
What is displacement?
A
- swept volume x number of cylinders
- measured in CC, L, CnIn
7
Q
What is clearance volume?
A
- volume of the combustion chamber above TDC
8
Q
What is compression ratio?
A
- difference in volume from BDC to TDC
- ## measured by dividing the two together between 14:1 -24:1 especially 17:1
9
Q
What does square mean?
A
- bore=stroke
- balance between the two
10
Q
What does over square mean?
A
- bore is bigger than the stoke
- higher torque, lower RPM
11
Q
What is under square mean?
A
- stroke is bigger than the bore
- lower torque, higher RPM
12
Q
What does valve overlap mean?
A
- when both valves intake and exhaust are open
- happens between exhaust and intake stroke and is there to help scavenge the last of the exhaust gases out of the engine
- measured in degrees of crankshaft rotation
13
Q
What does naturally aspirated mean?
A
- an engine that uses atmospheric pressure to fill the cylinders with air during the intake stroke
14
Q
What is forced induction?
A
- an engine that uses turbocharging or supercharging to fill the cylinders during intake stroke
15
Q
What is volume efficiency?
A
- ratio of cylinders liquid volume compared to volume of air drawn in during intake stroke
- naturally aspirated engines are typically less than 100%
16
Q
What is thermal efficiency?
A
- percentage of combustion energy that is turned into useful power typically between 30-40%
17
Q
What is torque?
A
- twisting force creating by the engine
- a measurement of force over a radial distance
- measured in Nm or lbs/ft
18
Q
What does horsepower mean?
A
- measurement of the rate which work is done
19
Q
What is work?
A
- force over distance
20
Q
What is rated horsepower?
A
- ## a calculation of much horsepower an engine should produce if friction and parasitic losses were zero
21
Q
What is brake horsepower?
A
- an engine horse power measured at the flywheel
- will be lower than rated due to losses in producing that power
