1. Measuring Engine Performance

2. The main goal of this chapter is to determine functional horsepower through different measurements and formulas

3. Small Gasoline Engine –Internal Combustion

4. Small Gasoline Engine –Internal Combustion Air/fuel mixture is ignited inside the engine

5. Small Gasoline Engine –Internal Combustion Air/fuel mixture is ignited inside the engine The gasses (when ignited ) expand in all directions

6. Small Gasoline Engine –Internal Combustion Air/fuel mixture is ignited inside the engine The gasses (when ignited ) expand in all directions Only the piston is allowed to move

7. Small Gasoline Engine –Internal Combustion Air/fuel mixture is ignited inside the engine The gasses (when ignited ) expand in all directions Only the piston is allowed to move –Inertia

8. Small Gasoline Engine –Internal Combustion Air/fuel mixture is ignited inside the engine The gasses (when ignited ) expand in all directions Only the piston is allowed to move –Inertia A physical law that states an object in motion will continue in motion or an object at rest will continue at rest unless an additional force is applied.

9. Small Gasoline Engine –Internal Combustion Air/fuel mixture is ignited inside the engine The gasses (when ignited ) expand in all directions Only the piston is allowed to move –Inertia A physical law that states an object in motion will continue in motion or an object at rest will continue at rest unless an additional force is applied. –The piston reaches TDC then reverses direction, repeating the process at BDC. This places extreme stress on the engine by changing the inertia

10. Performance Defined as the work engines do

11. Performance Defined as the work engines do also, Defined as how well they do the work

12. Bore The diameter or width across the top of the cylinder –Measured using caliper or telescoping gauges and micrometers

13. Stroke The up or down movement of the piston. –Measured from TDC to BDC. –Determined by the amount of offset on the crankshaft.

14. Stroke The up or down movement of the piston. –Measured from TDC to BDC. –Determined by the amount of offset on the crankshaft. or by the vernier depth gauge

15. An engine is considered square if the bore and stroke measurements are identical Square?

16. An engine is considered square if the bore and stroke measurements are identical An engine is considered over square if the bore diameter is greater than the stroke Square?

17. An engine is considered square if the bore and stroke measurements are identical An engine is considered over square if the bore diameter is greater than the stroke An engine is considered under square if the bore diameter is smaller than the stroke.

18. The total volume of space increase in the cylinder as the piston moves from the top to the bottom of its stroke. Engine Displacement

19. The total volume of space increase in the cylinder as the piston moves from the top to the bottom of its stroke. –Determined by the circular area of the cylinder then multiplied by the total length of the stroke. Engine Displacement

20. The total volume of space increase in the cylinder as the piston moves from the top to the bottom of its stroke. –Determined by the circular area of the cylinder then multiplied by the total length of the stroke. (V = π r 2 x stroke) or (V =.7854 D 2 x stroke)

21. Engine Displacement The total volume of space increase in the cylinder as the piston moves from the top to the bottom of its stroke. –Determined by the circular area of the cylinder then multiplied by the total length of the stroke. (V = π r 2 x stroke) or (V =.7854 D 2 x stroke) Engine Displacement:.7854 x D 2 x Length of stroke

22. Example –Bore = 2 ¼ in –Stroke = 2 ¼ in Engine Displacement

23. Example –Bore = 2 ¼ in –Stroke = 2 ¼ in.7854 x D 2 x Length of stroke Engine Displacement

24. Example –Bore = 2 ¼ in –Stroke = 2 ¼ in.7854 x D 2 x Length of stroke.7854 x (2.25 in) 2 x 2.25 in Engine Displacement

25. Example –Bore = 2 ¼ in –Stroke = 2 ¼ in.7854 x D 2 x Length of stroke.7854 x (2.25 in) 2 x 2.25 in.7854 x 5.0625 in 2 x 2.25 in Engine Displacement

26. Example –Bore = 2 ¼ in –Stroke = 2 ¼ in.7854 x D 2 x Length of stroke.7854 x (2.25 in) 2 x 2.25 in.7854 x 5.0625 in 2 x 2.25 in 8.95 in 3. or 8.95 cubic inches Engine Displacement

27. Example –Bore = 2 ¼ in –Stroke = 2 ¼ in.7854 x D 2 x Length of stroke.7854 x (2.25 in) 2 x 2.25 in.7854 x 5.0625 in 2 x 2.25 in 8.95 in 3. or 8.95 cubic inches –2 cylinder? Engine Displacement

28. Example –Bore = 2 ¼ in –Stroke = 2 ¼ in.7854 x D 2 x Length of stroke.7854 x (2.25 in) 2 x 2.25 in.7854 x 5.0625 in 2 x 2.25 in 8.95 in 3. or 8.95 cubic inches –2 cylinder? Multiply 8.95 in 3 x 2 = 17.89 in 3 Engine Displacement

29. Problem Bore = 2 inches Stroke = 2 inches 4 cylinder engine Determine the displacement using the above data and the formula below (.7854 x D 2 x Stroke = Displacement)

30. Problem.7854 x D 2 x Stroke = Displacement/Cylinder

31. Problem.7854 x D 2 x Stroke = Displacement/Cylinder.7854 x 2 2 in x 2 in = Displacement/Cylinder

32. Problem.7854 x D 2 x Stroke = Displacement/Cylinder.7854 x 2 2 in x 2 in = Displacement/Cylinder.7854 x 4 in 2 x 2 in = Displacement/Cylinder

33. Problem.7854 x D 2 x Stroke = Displacement/Cylinder.7854 x 2 2 in x 2 in = Displacement/Cylinder.7854 x 4 in 2 x 2 in = Displacement/Cylinder 6.28 in 3 = Displacement/Cylinder

34. Problem.7854 x D 2 x Stroke = Displacement/Cylinder.7854 x 2 2 in x 2 in = Displacement/Cylinder.7854 x 4 in 2 x 2 in = Displacement/Cylinder 6.28 in 3 = Displacement/Cylinder 6.28 in 3 x 4 cylinder = Total Displacement

35. Problem.7854 x D 2 x Stroke = Displacement/Cylinder.7854 x 2 2 in x 2 in = Displacement/Cylinder.7854 x 4 in 2 x 2 in = Displacement/Cylinder 6.28 in 3 = Displacement/Cylinder 6.28 in 3 x 4 cylinder = Total Displacement 25.12 in 3 Total Displacement

36. Compression Ratio The relationship between the total cylinder volume when the piston is a BDC and the volume remaining when the piston is at TDC. Small engines generally have 5-6:1 Some motorcycles have 9-10:1

37. Force The pushing or pulling of one body on another.

38. Force The pushing or pulling of one body on another. –Weight of you on a chair

39. Force The pushing or pulling of one body on another. –Weight of you on a chair –Centrifugal force The ball at the end of a string tries to move outward from its path when twirled

40. Force The pushing or pulling of one body on another. –Weight of you on a chair –Centrifugal force The body tries to move outward from its path when twirled –Tensile Stress the pushing or pulling stress (on the string)

41. Force The pushing or pulling of one body on another. –Weight of you on a chair –Centrifugal force The body tries to move outward from its path when twirled –Tensile Stress the pushing or pulling stress –Ex. The piston reversing direction several times a second

42. Work Accomplished only when a force is applied through some distance

43. Work Accomplished only when a force is applied through some distance Work = Distance x Force

44. Work Accomplished only when a force is applied through some distance Work = Distance x Force –Distance (ft), Force (lb)

45. Work Accomplished only when a force is applied through some distance Work = Distance x Force –Distance (ft), Force (lb) –Work Unit = ft·lb

46. Power The rate at which work is done

47. Power The rate at which work is done Power = Work / Time

48. Power The rate at which work is done Power = Work / Time Power = Pounds x Distance / Time

49. Power The rate at which work is done Power = Work / Time Power = Pounds x Distance / Time –Example: a horse can lift 100 lb a distance of 330 ft in 1 minute. How much Power is used?

50. Power The rate at which work is done Power = Work / Time Power = Pounds x Distance / Time –Example: a horse can lift 100 lb a distance of 330 ft in 1 minute. How much Power is used? –Power = 330 ft x 100 lb / 60 sec

51. Power The rate at which work is done Power = Work / Time Power = Pounds x Distance / Time –Example: a horse can lift 100 lb a distance of 330 ft in 1 minute. How much Power is used? –Power = 330 ft x 100 lb / 60 sec –Power = 550 ft·lb/sec

52. Power The rate at which work is done Power = Work / Time Power = Pounds x Distance / Time –Example: a horse can lift 100 lb a distance of 330 ft in 1 minute. How much Power is used? –Power = 330 ft x 100 lb / 60 sec –Power = 550 ft·lb/sec –1 horse power = 550 ft·lb/sec

53. Horsepower Calculate the amount of work and engine does and divide it by 550 ft·lb/sec. This will give the rated horsepower.

54. Horsepower Calculate the amount of work and engine does and divide it by 550 ft·lb/sec. This will give the rated horsepower. Brake Horsepower

55. Horsepower Calculate the amount of work and engine does and divide it by 550 ft·lb/sec. This will give the rated horsepower. Brake Horsepower –Usable horsepower

56. Horsepower Calculate the amount of work and engine does and divide it by 550 ft·lb/sec. This will give the rated horsepower. Brake Horsepower –Usable horsepower –Measured by

57. Horsepower Calculate the amount of work and engine does and divide it by 550 ft·lb/sec. This will give the rated horsepower. Brake Horsepower –Usable horsepower –Measured by Prony brake (fiction) Dynamometer (hydraulics)

58. Horsepower Increases with increased speeds.

59. Horsepower Increases with increased speeds. Engines generally run at 3600 rpm.

60. Torque A twisting or turning force

61. Torque A twisting or turning force Torque = Distance (radius) x Force

62. Torque A twisting or turning force Torque = Distance (radius) x Force Torque = Feet x Pounds

63. Torque A twisting or turning force Torque = Distance (radius) x Force Torque = Feet x Pounds Torque = ft·lb

64. Torque A twisting or turning force Torque = Distance (radius) x Force Torque = Feet x Pounds Torque = ft·lb 1 ft·lb = 12 in·lb

65. Torque A twisting or turning force Torque = Distance (radius) x Force Torque = Feet x Pounds Torque = ft·lb 1 ft·lb = 12 in·lb Engine Torque increases with increased rpm, but decreases if rpm is becomes too high.

66. Review Why do we check engine performance? What type of forces are working in an internal combustion engine? Explain the difference between bore & stroke. How is displacement measured? What is the unit for work? What is the unit for power? What is 1 horsepower? Torque is measured in ______ for units