Engine Terms Flashcards

1
Q

What does TDC mean?

A
  • top dead centre
  • upper most limit of the piston
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2
Q

what does BDC mean?

A
  • bottom dead centre
  • lowest limit of piston travel
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3
Q

What does bore mean?

A
  • internal diameter of a cylinder
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4
Q

What does stroke mean?

A
  • the distance between TDC AND BDC
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5
Q

What does swept volume mean?

A
  • volume of cylinder between TDC and BDC
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6
Q

What is displacement?

A
  • swept volume x number of cylinders
  • measured in CC, L, CnIn
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7
Q

What is clearance volume?

A
  • volume of the combustion chamber above TDC
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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
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9
Q

What does square mean?

A
  • bore=stroke
  • balance between the two
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10
Q

What does over square mean?

A
  • bore is bigger than the stoke
  • higher torque, lower RPM
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11
Q

What is under square mean?

A
  • stroke is bigger than the bore
  • lower torque, higher RPM
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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
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13
Q

What does naturally aspirated mean?

A
  • an engine that uses atmospheric pressure to fill the cylinders with air during the intake stroke
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14
Q

What is forced induction?

A
  • an engine that uses turbocharging or supercharging to fill the cylinders during intake stroke
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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%
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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