Publisher The Goodheart-Willcox Co., Inc. Tinley Park, Illinois

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

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 rotationsare required to complete thefour-stroke cycle • Almost all automobiles usefour-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 theair-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. Engine Block Forms the main body of the engine

17. Engine Block Parts • Cylinders • 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 • 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. Crankshaft Fits into the bottom of the block

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

47. Cylinder Head Parts • Intake 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 • 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. Cylinder Head Parts When the valve is closed, it sealsagainst the valve seat

50. Valve Train Consists of the valves and the partsthat operate them