Chapter 6 Measuring Engine Performance page 91
Basic Terminology <ul><li>Bore & Stroke </li></ul><ul><li>Engine Displacement </li></ul><ul><li>Compression Ratio </li></u...
Bore <ul><li>Diameter of cylinder </li></ul><ul><li>2 X Radius </li></ul>
Stroke <ul><li>Distance  </li></ul><ul><ul><li>TDC-BDC </li></ul></ul><ul><li>Distance piston travels </li></ul><ul><ul><l...
Cylinder Displacement <ul><li>0.7854 x D2 x stroke </li></ul><ul><li>or </li></ul><ul><li>Π  x r2 x Stroke </li></ul>
Engine Displacement <ul><li>0.7854 x D 2  x stroke X # of cylinders </li></ul><ul><li>or </li></ul><ul><li>Π  x r 2  x Str...
Compression Ratio <ul><li>Volume of cylinder at BDC </li></ul><ul><li>compared to  </li></ul><ul><li>Area of cylinder at T...
Force <ul><li>pushing or pulling </li></ul><ul><li>stationary force </li></ul><ul><li>moving force </li></ul><ul><li>Centr...
Pressure <ul><li>Pressure is force per given area </li></ul><ul><li>or  </li></ul><ul><li>Force/Area </li></ul><ul><li>PSI...
Work <ul><li>force applied resulting in movement </li></ul><ul><li>Work = Force  x Distance </li></ul><ul><li>W = F x D </...
Mechanical Advantage <ul><li>2’ </li></ul>10’ 10’ / 2’ = 5 = MA E(effort) = R(resistance)/ MA or E = 500# / 5 = 100 # 500#
Power <ul><li>Power is time taken to do the work </li></ul><ul><li>P = work/time </li></ul><ul><li>P=W/T </li></ul><ul><li...
Energy <ul><li>Energy can not be created or destroyed </li></ul><ul><li>Potential—has the potential to . . . </li></ul><ul...
Horsepower <ul><li>Power = work / time P= w/t </li></ul><ul><li>Hp = 33,00 ft-lb (work) / 1 minute (time) </li></ul><ul><l...
Horsepower Formula <ul><li>100 ft x 330 lb / 6 seconds = 5500 ft lb / sec </li></ul><ul><li>dividing this by 550 ft lb / s...
Kinds of Horsepower <ul><li>Brake Horsepower </li></ul><ul><li>Indicated Horsepower </li></ul><ul><li>Frictional Horsepowe...
Brake Horsepower <ul><li>bhp </li></ul><ul><li>actual hp delivered </li></ul><ul><li>what we can use </li></ul>
Indicated Horsepower <ul><li>ihp (perfect world) </li></ul><ul><li>power developed by the burning fuel </li></ul><ul><li>a...
Frictional Horsepower <ul><li>fhp </li></ul><ul><li>HP lost because of drag </li></ul><ul><li>fhp = ihp-bhp </li></ul>
Rated Horsepower <ul><li>rhp  </li></ul><ul><li>80% of bhp </li></ul>
Corrected Horsepower <ul><li>corrected for elevation (sea level) </li></ul><ul><li>corrected for temperature </li></ul><ul...
Torque <ul><li>Twisting force </li></ul><ul><li>force x distance </li></ul><ul><li>ft - lb </li></ul><ul><li>in – lb </li>...
Torque is not Constant <ul><li>Torque will change w/ engine speed </li></ul><ul><li>More pressure on piston = more torque ...
Torque and Horsepower <ul><li>Unlike torque. . . </li></ul><ul><li>Horsepower increases with engine speed </li></ul><ul><l...
Torque and power curves: Skyline
Volumetric Efficiency <ul><li>How well an engine breathes </li></ul><ul><ul><li>draws air/fuel into cylinder </li></ul></u...
Practical Efficiency <ul><li>How efficiently an engine uses the fuel </li></ul>
Mechanical Efficiency <ul><li>% of power developed in cylinder (ihp) </li></ul><ul><li>compared to  </li></ul><ul><li>powe...
Thermal Efficiency <ul><li>Heat efficiency </li></ul><ul><li>How much power produced is used to push the piston down </li>...
Brake thermal efficiency <ul><li>=  </li></ul><ul><li>Brake horsepower  (bhp x 33,000) </li></ul><ul><li>778  Fuel heat va...
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Measuring performance

  1. 1. Chapter 6 Measuring Engine Performance page 91
  2. 2. Basic Terminology <ul><li>Bore & Stroke </li></ul><ul><li>Engine Displacement </li></ul><ul><li>Compression Ratio </li></ul><ul><li>Force </li></ul><ul><li>Work </li></ul><ul><li>Power </li></ul><ul><li>Energy </li></ul><ul><li>Horsepower </li></ul>
  3. 3. Bore <ul><li>Diameter of cylinder </li></ul><ul><li>2 X Radius </li></ul>
  4. 4. Stroke <ul><li>Distance </li></ul><ul><ul><li>TDC-BDC </li></ul></ul><ul><li>Distance piston travels </li></ul><ul><ul><li>up or down </li></ul></ul>
  5. 5. Cylinder Displacement <ul><li>0.7854 x D2 x stroke </li></ul><ul><li>or </li></ul><ul><li>Π x r2 x Stroke </li></ul>
  6. 6. Engine Displacement <ul><li>0.7854 x D 2 x stroke X # of cylinders </li></ul><ul><li>or </li></ul><ul><li>Π x r 2 x Stroke x # of cylinders </li></ul><ul><li>in 3 / 62 = Liters </li></ul>
  7. 7. Compression Ratio <ul><li>Volume of cylinder at BDC </li></ul><ul><li>compared to </li></ul><ul><li>Area of cylinder at TDC </li></ul>
  8. 8. Force <ul><li>pushing or pulling </li></ul><ul><li>stationary force </li></ul><ul><li>moving force </li></ul><ul><li>Centrifugal force </li></ul><ul><ul><li>spinning </li></ul></ul><ul><ul><li>FORCE does NOT = Pressure </li></ul></ul>
  9. 9. Pressure <ul><li>Pressure is force per given area </li></ul><ul><li>or </li></ul><ul><li>Force/Area </li></ul><ul><li>PSI </li></ul><ul><li>Force = psi X area </li></ul><ul><li>Area = force / psi </li></ul><ul><li>Area = Π R 2 </li></ul>
  10. 10. Work <ul><li>force applied resulting in movement </li></ul><ul><li>Work = Force x Distance </li></ul><ul><li>W = F x D </li></ul><ul><li>Mechanical advantage (lever, ramp, etc) </li></ul><ul><li>Effort distance / resistance distance = Mechanical advantage </li></ul>
  11. 11. Mechanical Advantage <ul><li>2’ </li></ul>10’ 10’ / 2’ = 5 = MA E(effort) = R(resistance)/ MA or E = 500# / 5 = 100 # 500#
  12. 12. Power <ul><li>Power is time taken to do the work </li></ul><ul><li>P = work/time </li></ul><ul><li>P=W/T </li></ul><ul><li>Power = feet x Pounds / time </li></ul><ul><li>or Foot pounds per second? </li></ul>
  13. 13. Energy <ul><li>Energy can not be created or destroyed </li></ul><ul><li>Potential—has the potential to . . . </li></ul><ul><li>Kinetic </li></ul><ul><li>Mechanical </li></ul><ul><li>Chemical </li></ul><ul><li>Thermal (heat) </li></ul><ul><li>Light </li></ul>
  14. 14. Horsepower <ul><li>Power = work / time P= w/t </li></ul><ul><li>Hp = 33,00 ft-lb (work) / 1 minute (time) </li></ul><ul><li>or </li></ul><ul><li>Hp = 550 ft-lb / 1 second </li></ul>
  15. 15. Horsepower Formula <ul><li>100 ft x 330 lb / 6 seconds = 5500 ft lb / sec </li></ul><ul><li>dividing this by 550 ft lb / sec (1hp) </li></ul><ul><li>= </li></ul><ul><li>(5500 ft-lb /sec) / (550 ft lb / sec) = 10 hp </li></ul><ul><li>thus </li></ul><ul><li>1 hp = rate of work in ft-lb/sec / 50 ft-lb / sec </li></ul>
  16. 16. Kinds of Horsepower <ul><li>Brake Horsepower </li></ul><ul><li>Indicated Horsepower </li></ul><ul><li>Frictional Horsepower </li></ul><ul><li>Rated Horsepower </li></ul><ul><li>Corrected Horsepower </li></ul>
  17. 17. Brake Horsepower <ul><li>bhp </li></ul><ul><li>actual hp delivered </li></ul><ul><li>what we can use </li></ul>
  18. 18. Indicated Horsepower <ul><li>ihp (perfect world) </li></ul><ul><li>power developed by the burning fuel </li></ul><ul><li>average of power on 4 strokes (mean) </li></ul><ul><li>PLANK / 33,000 </li></ul><ul><li>P = mep in lb/in 2 </li></ul><ul><li>L = length of stroke </li></ul><ul><li>A = Cylinder Area </li></ul><ul><li>N = power strokes per minute or RPM / 4 </li></ul><ul><li>K = # of cylinders </li></ul>
  19. 19. Frictional Horsepower <ul><li>fhp </li></ul><ul><li>HP lost because of drag </li></ul><ul><li>fhp = ihp-bhp </li></ul>
  20. 20. Rated Horsepower <ul><li>rhp </li></ul><ul><li>80% of bhp </li></ul>
  21. 21. Corrected Horsepower <ul><li>corrected for elevation (sea level) </li></ul><ul><li>corrected for temperature </li></ul><ul><li>barometric pressure </li></ul><ul><li>quality of fuel </li></ul><ul><li>humidity </li></ul>
  22. 22. Torque <ul><li>Twisting force </li></ul><ul><li>force x distance </li></ul><ul><li>ft - lb </li></ul><ul><li>in – lb </li></ul><ul><li>Newton - Meters </li></ul>
  23. 23. Torque is not Constant <ul><li>Torque will change w/ engine speed </li></ul><ul><li>More pressure on piston = more torque </li></ul>
  24. 24. Torque and Horsepower <ul><li>Unlike torque. . . </li></ul><ul><li>Horsepower increases with engine speed </li></ul><ul><li>Torque measure of engine’s twisting force </li></ul><ul><li>Hp measures engine’s ability to do work </li></ul>
  25. 25. Torque and power curves: Skyline
  26. 26. Volumetric Efficiency <ul><li>How well an engine breathes </li></ul><ul><ul><li>draws air/fuel into cylinder </li></ul></ul><ul><li>Can decrease as engine speed increases </li></ul><ul><li>Many factors </li></ul>
  27. 27. Practical Efficiency <ul><li>How efficiently an engine uses the fuel </li></ul>
  28. 28. Mechanical Efficiency <ul><li>% of power developed in cylinder (ihp) </li></ul><ul><li>compared to </li></ul><ul><li>power delivered to crankshaft (bhp) </li></ul><ul><li>friction, </li></ul><ul><li>Mechanical efficiency = bhp/ihp </li></ul>
  29. 29. Thermal Efficiency <ul><li>Heat efficiency </li></ul><ul><li>How much power produced is used to push the piston down </li></ul><ul><li>Power is lost to : </li></ul><ul><ul><li>cooling </li></ul></ul><ul><ul><li>exhaust </li></ul></ul><ul><ul><li>20-25% efficient </li></ul></ul><ul><ul><li>Exhaust 35% . . . </li></ul></ul><ul><ul><li>Cooling & Lubrication 35% </li></ul></ul>
  30. 30. Brake thermal efficiency <ul><li>= </li></ul><ul><li>Brake horsepower (bhp x 33,000) </li></ul><ul><li>778 Fuel heat value x weight of burned fuel per minute </li></ul><ul><li>778 is Joule’s equivalent </li></ul><ul><li>it is a constant </li></ul>

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