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Modern Automotive Technology. by Russell Krick. Publisher The Goodheart-Willcox Co., Inc. Tinley Park, Illinois. PowerPoint for. Body. Made of sheet metal, plastic, or fiberglass parts Forms the passenger compartment Serves as an attractive covering for the chassis Chassis
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Modern Automotive Technology by Russell Krick PublisherThe Goodheart-Willcox Co., Inc.Tinley Park, Illinois PowerPoint for
Body • Made of sheet metal, plastic, or fiberglass parts • Forms the passenger compartment • Serves as an attractive covering for the chassis • Chassis • includes the engine, suspension, steering, brakes, wheels, tires, etc.
Frame • Strong metal structure that supports various vehicle components • Body-over-frame construction • body bolts on to the frame • Unitized (unibody) construction • inner body sections support the engine, suspension, and other major assemblies
Unibody Construction Frame is an integral part of the body
Sedan Uses center body pillars, or “B” pillars, between the front and rear doors Has 4 doors
Coupe 2 door car
Convertible Uses a vinyl or cloth top that can be raised or lowered
Hatchback Large rear door allows easy accesswhen hauling items
Station Wagon Provides a large rear interior compartment
Minivan Has a higher roofline for moreheadroom and cargo space
Sport-utility Vehicle Provides the comfort of a passenger car, the interior space of a station wagon, and the durability of a truck
Vehicle Identification • Door Jam
Vehicle Identification • Windshield
Vehicle Identification • Under hood
Four-Stroke Cycle • Four separate piston strokes are needed to produce one cycle • Piston must slide down, up, down, and up again to complete one cycle • Piston strokes required: • intake • compression • power • exhaust
Intake Stroke Draws the air-fuel mixture into the cylinder
Compression Stroke Compresses the air-fuel mixture
Power Stroke Produces the force to operate the engine
Exhaust Stroke Removes the burned gases from the combustion chamber
Number of Cylinders • Most car and truck engines have either 4, 6, or 8 cylinders • Some may have 3, 5, 10, 12, or 16 cylinders • Engine power and smoothness are enhanced by using more cylinders
L-head Engine Both the intake and exhaust valves are in the block
I-head Engine Both valves are in the cylinder head
Overhead Cam Engine Camshaft is located in the top of the cylinder head
Overhead Cam Engine • OHC engines may use one or two camshafts: • Single overhead cam (SOHC) engine • uses only one camshaft per cylinder head • Double overhead cam (DOHC) engine • uses two camshafts per cylinder head • one cam operates the intake valves, while the other cam operates the exhaust valves
Pancake Combustion Chamber Valve heads are almost parallel to the top of the piston. Chamber forms a flat pocket over the piston head
Wedge Combustion Chamber Domed Piston Provides good air-fuel mixing at low engine speeds Flat Top Piston
Hemispherical Combustion Chamber First used in high-horsepower racing engines. Excellent design for high-rpm use
Rotary Engine • Uses a triangular rotor instead of pistons • Rotor orbits a main-shaft inside a specially shaped chamber • This eliminates the reciprocating motion found in piston engines
Rotary Engine Animation http://www.animatedengines.com/wankel.shtml
piston ( radius squared) x strokedisplacement = Piston Displacement • Volume the piston displaces as it travels from BDC to TDC • Found by comparing cylinder diameter and piston stroke • Piston displacement formula:
If an engine has a bore of 4” and a stroke of 3”, what is its piston displacement? piston (22) x 3.14 x 3displacement 4 x 3.14 x 3 37.68 cu. in. = = = Piston Displacement
Compression Ratio This engine has eight times the volume at BDC, producing an 8:1 compression ratio
Compression Ratio • Formula for compression ratio: compression cylinder volume at BDCratio cylinder volume at TDC • Use of high compression ratio: • increases engine fuel efficiency and power • increases exhaust emissions (NOx) • increases risk of detonation =
Compression Pressure • Amount of pressure in the cylinder on the compression stroke • Measured in pounds per square inch (psi) or kilopascals (kPa) • Gasoline engine compression pressure: • 130–180 psi (900–1200 kPa) • Diesel engine compression pressure: • 250–400 psi (1700–2800 kPa)
Horsepower One horsepower equals 33,000 ft lb of work per minute
Horsepower For a small engine to lift 500 pounds a distance of 700 feet in one minute, about how much horsepower would be needed? hp = 500 lb x 700’ 33,000 = 10.6 hp