1. Modern Automotive Technology PowerPoint for by Russell Krick
Publisher The Goodheart-Willcox Co., Inc. Tinley Park, Illinois

2. Chapter 11
Engine Fundamentals

3. Contents Engine operation Engine bottom end Engine top end
Engine front end

4. Engine Operation The engine is the source of power for the vehicle
It converts the energy stored in fuel into motion

5. Engine Operation
Fuel is burned inside the engine’s combustion chamber to produce heat
Heat causes expansion of gases in the engine
Expansion in the combustion chamber produces pressure
Engine components convert pressure into rotating motion

6. Engine Operation

7. Piston Travel (TDC, BDC)
Top dead center (TDC)
piston is at its highest point in the cylinder
Bottom dead center (BDC)
piston is at its lowest point in the cylinder
Piston stroke
distance the piston slides up or down from TDC to BDC

8. Piston Travel (TDC, BDC)

9. Four-Stroke Cycle Requires four piston strokes to complete one cycle
Every four strokes, the engine produces one power stroke
Two complete crankshaft rotations are required to complete the four-stroke cycle
Almost all automobiles use four-stroke-cycle engines

10. Intake Stroke Draws fuel and air into the engine Intake valve is open
Exhaust valve is closed
Piston slides down and forms a low pressure area in the cylinder
Atmospheric pressure pushes the air-fuel mixture into the cylinder

11. Compression Stroke
Compresses (squeezes) the air-fuel mixture, making it more combustible
Piston slides upward
Both valves are closed

12. Power Stroke
Burns the air-fuel mixture and pushes the piston down with tremendous force
Both valves are closed
Spark plug fires, igniting the air-fuel mixture
Pressure forms on the top of the piston
Piston is forced down, rotating the crankshaft

13. Exhaust Stroke Removes the burned gases from the cylinder
Piston moves upward
Intake valve is closed
Exhaust valve is open
Burned gases are pushed out the exhaust port

14. Four-Stroke Cycle

15. Engine Bottom End
Refers to the block, crankshaft, connecting rods, pistons, and related components
Another name for the bottom end is the short block

16. Forms the main body of the engine
Engine Block
Forms the main body of the engine

17. Engine Block Parts Cylinders Water jackets
large, round holes machined through the block
Water jackets
coolant passages through the block
allow a solution of water and antifreeze to cool the cylinders

18. Engine Block Parts Core (freeze) plugs Main bearing bores Main caps
round metal plugs that seal holes left in the block after casting
Main bearing bores
holes machined in the bottom of the block to hold the crankshaft
Main caps
hold the crankshaft and main bearing inserts in place

19. Crankshaft
Harnesses the tremendous force produced by the downward thrust of the pistons
Changes the reciprocating (up-and-down) motion of the pistons into rotating motion

20. Fits into the bottom of the block
Crankshaft
Fits into the bottom of the block

21. Journals are precision-ground surfaces for the bearings
Crankshaft Parts
Journals are precision-ground surfaces for the bearings

22. Crankshaft Parts
Counterweight offsets the weight of the piston, rod, rings, and journal offset to prevent vibration

23. Crankshaft Parts Crankshaft snout Crankshaft flange
sticks through the front of the block
provides a mounting place for the camshaft drive mechanism, front damper, and pulleys
Crankshaft flange
holds the flywheel

24. Engine Main Bearings
Removable inserts that fit between the block main bore and the crankshaft main journals
One-half of each insert fits into the block, while the other half fits into the block main cap
A main thrust bearing has flanges to control crankshaft end play

25. Oil holes and grooves allow oil to lubricate the bearings
Engine Main Bearings
Oil holes and grooves allow oil to lubricate the bearings

26. Main Bearing Clearance
Space between the crankshaft main journal and the main bearing insert
Allows lubricating oil to enter and separate the journal and bearing
this allows the journal to rotate without rubbing on the bearing and causing excess wear

27. Engine Bottom End

28. Crankshaft Oil Seals
Keep oil from leaking out the front and rear of the engine
Seals are placed around the front and rear of the crankshaft to contain this oil
Rear main oil seal
one- or two-piece seal that fits around the rear of the crankshaft to prevent oil leakage
Front main oil seal
one-piece seal pressed into the front cover

29. Flywheel Large metal disk mounted on the rear of the crankshaft
Flywheel functions:
connects the crankshaft to the transmission or transaxle through a clutch or torque converter
helps smooth engine power pulses
contains a large ring gear, which meshes with the starting motor gear to start the engine

30. Connecting Rod Fastens the piston to the crankshaft
Transfers piston movement and combustion pressure to the crankshaft rod journals
Causes piston movement during the non-power producing strokes
intake, compression, and exhaust

31. Connecting Rod

32. Connecting Rod Bearings
Ride on the crankshaft rod journals
Fit between the connecting rods and the crankshaft
Rod bearing clearance
small space between the rod bearing and crankshaft journal
allows oil to enter the bearing, preventing metal-to-metal contact

33. Piston
Transfers the pressure of combustion to the connecting rod and crankshaft

34. Allows the piston to swing on the connecting rod
Piston (Wrist) Pin
Allows the piston to swing on the connecting rod

35. Piston Clearance
The amount of space between the sides of the piston and the cylinder wall
Allows a lubricating film of oil to form between the piston and the cylinder
Allows for expansion when the piston heats up

36. Piston Rings
Seal the clearance between the outside of the piston and the cylinder wall
Keep combustion pressure from entering the crankcase
Keep oil from entering the combustion chambers

37. Piston Rings

38. Compression Rings
Prevent blowby (compression pressure leaking into the engine crankcase)
Compression and combustion pressure push the compression rings down in their grooves and out against the cylinder wall, improving sealing

39. Compression Rings

40. Oil Rings Prevent engine oil from entering the combustion chamber
Scrape excess oil off the cylinder wall
If too much oil gets into the combustion chamber, it will burn, causing blue exhaust smoke and increased exhaust emissions

41. Oil Rings

42. Ring Gap Split, or space, between the ends of a piston ring
Allows the ring to be spread open and installed on the piston
Allows the ring to be made slightly larger in diameter than the cylinder
when installed in the cylinder, the ring spreads outward and presses on the cylinder wall, aiding ring sealing

43. Engine Top End
Refers to the cylinder heads, valves, camshaft, and other related components
These parts work together to control the flow of air and fuel into the engine cylinders
They also control the flow of exhaust out of the engine

44. ENGINE
TOP END

45. Cylinder Head Bolts to the deck of the cylinder block
Covers and encloses the top of the cylinders
Combustion chambers are small pockets formed in the cylinder head
combustion occurs in these small pockets

46. Combustion chambers contain the spark plug tip and valve seats
Cylinder Head
Combustion chambers contain the spark plug tip and valve seats

47. Cylinder Head Parts Intake ports Exhaust ports
route air (diesel engine) or air and fuel (gasoline engine) into the combustion chamber
Exhaust ports
route burned gases out of the combustion chamber

48. Cylinder Head Parts Valve guides Valve seats
small holes machined through the cylinder head for the valves
valves slide in these guides
Valve seats
machined surfaces in the combustion chamber port openings

49. When the valve is closed, it seals against the valve seat
Cylinder Head Parts
When the valve is closed, it seals against the valve seat

50. Consists of the valves and the parts that operate them
Valve Train
Consists of the valves and the parts that operate them

51. The camshaft lobe turns into the lifter and the valve is pushed open
Valve Train Operation
The camshaft lobe turns into the lifter and the valve is pushed open
The lobe rotates away from the lifter and the valve spring pushes the valve closed

52. Located in the engine block or in the cylinder head
Camshaft
Located in the engine block or in the cylinder head

53. Camshaft Parts Cam lobes Eccentric Camshaft journals
egg-shaped protrusions machined on the camshaft
one lobe is provided for each engine valve
Eccentric
may be machined on the camshaft for a mechanical fuel pump
Camshaft journals
machined surfaces for the cam bearings

54. Valve Lifters
Usually rides on the cam lobes and transfers motion to the rest of the valve train
Located in the engine block or cylinder head
Fit into lifter bores, which are machined holes in the block or head

55. Push Rods Transfer motion between the lifters and the rocker arms
Needed when the camshaft is located in the cylinder block
Made from a hollow metal tube with a ball or socket formed on each end
One end fits into the lifter, while the other end fits against the rocker arm

56. Rocker Arms Used to transfer motion to the valves
Mount on top of the cylinder head
Rocker arm movement allows the camshaft lobe to force the valve open
Valve spring force closes the valve and keeps the rocker arm in contact with the push rod

57. Open and close the ports in the cylinder head
Valves
Open and close the ports in the cylinder head

58. Intake Valve Larger than the exhaust valve
Controls the flow of the air-fuel mixture (gasoline engine) or air (diesel) into the combustion chamber
Fits into the port leading from the intake manifold

59. Exhaust Valve Controls the flow of exhaust gases out of the cylinder
Smaller than the intake valve
Fits into the port leading to the exhaust manifold

60. Valve Seals
Prevent oil from entering the combustion chambers through the valve guides

61. Valve Spring Assembly
Used to close the valve

62. Intake Manifold Bolts to the side of the cylinder head
Contains runners going to each cylinder head port
Air and fuel (gasoline engine) are routed through these runners

63. Exhaust Manifold Bolts to the cylinder head
Fastens over the exhaust ports to carry burned gases to the exhaust system
Made of cast iron, lightweight aluminum, or stainless steel tubing

64. Engine Manifolds

65. Valve (Rocker) Cover
Thin metal or plastic cover over the top of the cylinder head
Keeps valve train oil spray from leaking out of the engine

66. Engine Front End
Operates the engine camshaft and sometimes the oil pump, distributor, engine sensors, and diesel injection pump
Consists of a drive mechanism, a front cover, an oil seal, and a crankshaft damper

67. Camshaft Drive Needed to turn the camshaft at one-half engine speed
Often called the timing belt, timing chain, or timing gears because they time the camshaft with the crankshaft

68. Camshaft Drive
A belt-drive, chain-drive, or gear-drive may be used to turn the camshaft

69. Front Cover Bolts over the crankshaft snout
Holds an oil seal that seals the front of the crankshaft
When the engine uses a gear- or chain-type camshaft drive, the front cover may be called the timing cover

70. Engine Front End

71. Timing Belt
The front cover houses the front oil seal. The timing cover fits over the belt.

72. Timing chain and sprockets operate the camshaft in this engine

73. Crank Damper Heavy wheel on the crankshaft snout Mounted in rubber
Helps prevent crankshaft vibration and damage
Also called the harmonic balancer or vibration damper