10. Figure 3-1 The downward movement of the piston draws the air-fuel mixture into the cylinder through the intake valve on the intake stroke. On the compression stroke,the mixture is compressed by the upward movement of the piston with both valves closed. Ignition occurs at the beginning of the power stroke, and combustion drives the piston downward to produce power. On the exhaust stroke,the upward-moving piston forces the burned gases out the open exhaust valve.

11. Figure 3-2 Cutaway of an engine showing the cylinder, piston, connecting rod, and crankshaft.

20. Figure 3-3 Automotive engine cylinder arrangements.

21. Figure 3-4 A horizontally opposed engine design helps to lower the vehicle’s center of gravity.

22. Figure 3-5 Automotive engine cylinder arrangements.

23. Figure 3-6 Two types of front-engine, front-wheel drive.

24. Figure 3-7 Cutaway of a V-8 engine showing the lifters, pushrods, roller rocker arms, and valves.

25. Figure 3-8 SOHC engines usually require additional components such as a rocker arm to operate all of the valves. DOHC engines often operate the valves directly.

26. Figure 3-9 A dual overhead camshaft (DOHC) V-8 engine with part of the cam cover cut away.

27. Figure 3-10 Rotary engine operates on the 4-stroke cycle but uses a rotor instead of a piston and crankshaft to achieve intake, compression, power, and exhaust strokes.

28. Figure 3-11 Inline 4-cylinder engine showing principal and nonprincipal ends. Normal direction of rotation is clockwise (CW) as viewed from the front or accessory belt end (nonprincipal end).

30. Figure 3-12 The bore and stroke of pistons are used to calculate an engine’s displacement.

37. (Continued) Less ignition timing required to prevent spark knock (detonation) More advanced ignition timing possible without spark knock (detonation) Harder to crank engine, especially when hot Easier engine cranking Better fuel economy. Poorer fuel economy Higher power possible. Lower power If Compression Is Higher If Compression Is Lower

40. Figure 3-13 Compression ratio is the ratio of the total cylinder volume (when the piston is at the bottom of its stroke) to the clearance volume (when the piston is at the top of its stroke).

41. Figure 3-14 Combustion chamber volume is the volume above the piston with the piston at top dead center.

42. Figure 3-15 The distance between the centerline of the main bearing journal and the centerline of the connecting rod journal determines the stroke of the engine. This photo is a little unusual because this is from a V-6 with a splayed crankshaft used to even the impulses on a 90 degree, V-6 engine design.

45. Figure 3-16 Torque is a twisting force equal to the distance from the pivot point times the force applied expressed in units called pound-feet (lb.-ft.) or Newton-meters (N-m).

47. Figure 3-17 Work is calculated by multiplying force times distance. If you exert 100 pounds of force for 10 feet, you have done 1000 foot-pounds of work.

51. Figure 3-18 One horsepower is equal to 33,000 foot-pounds (200 lbs. X 165 ft.) of work per minute.

60. Figure 3-19 Diesel combustion occurs when fuel is injected into the hot, highly compressed air in the cylinder.

61. Figure 3-20 A typical injector-pump-type automotive diesel fuel-injection system.

62. Figure 3-21 An indirect injection diesel uses a prechamber and a glow plug.

63. Figure 3-22 A direct injection diesel engine injects the fuel directly into the combustion chamber. Many designs do not use a glow plug.

67. Figure 3-23 The common rail on a Cummins diesel engine. A high-pressure pump (up to 30,000 psi) is used to supply diesel fuel to this common rail, which has tubes running to each injector. Note the thick cylinder walls and heavy-duty construction.

68. Figure 3-24 A rod/piston assembly from a 5.9-liter Cummins diesel engine used in a Dodge pickup truck.

71. Figure 3-25 Using an ice bath to test the fuel temperature sensor.

75. Figure 3-26 A typical distributor-type diesel injection pump showing the pump, lines, and fuel filter.

76. Figure 3-27 Overview of a computer-controlled common rail V-8 diesel engine.

81. Figure 3-28 Typical computer-controlled diesel engine fuel injectors.

84. Figure 3-29 A schematic of a typical glow plug circuit. Notice that the relay for the glow plug and intake air heater are both computer controlled.

88. Figure 3-30 A roller lifter from a GM Duramax 6.6-liter V-8 diesel engine. Notice the size of this lifter compared to a roller lifter used in a gasoline engine.