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PowerPoint for
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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.

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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

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Unibody Construction

• Frame is an integral part of the body

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Body-on-Frame Construction
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Sedan

• Uses center body pillars, or B pillars, between
  the front and rear doors
• Has 4 doors

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Coupe
2 door car
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Convertible

• Uses a vinyl or cloth top that can be raised or
  lowered

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Hatchback

• Large rear door allows easy accesswhen hauling
  items

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Station Wagon

• Provides a large rear interior compartment

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Minivan

• Has a higher roofline for moreheadroom and cargo
  space

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Sport-utility Vehicle

• Provides the comfort of a passenger car, the
  interior space of a station wagon, and the
  durability of a truck

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Automobile Body Parts
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Engine Locations
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Vehicle Identification

• Door Jam

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Vehicle Identification

• Windshield

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Vehicle Identification

• Under hood

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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

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4 Stroke Engine
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Intake Stroke

• Draws the air-fuel mixture into the cylinder

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Compression Stroke

• Compresses the air-fuel mixture

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Power Stroke

• Produces the force to operate the engine

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Exhaust Stroke

• Removes the burned gases from the combustion
  chamber

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Cylinder Arrangement
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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

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Cylinder Numbering and Firing Order
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L-head Engine

• Both the intake and exhaust valves are in the
  block

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I-head Engine

• Both valves are in the cylinder head

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Overhead Cam Engine

• Camshaft is located in the top of the cylinder
  head

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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

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Pancake Combustion Chamber

• Valve heads are almost parallel to the top of the
  piston. Chamber forms a flat pocket over the
  piston head

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Wedge Combustion Chamber
Domed Piston
Flat Top Piston

• Provides good air-fuel mixing at low engine speeds

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Hemispherical Combustion Chamber

• First used in high-horsepower racing engines.
  Excellent design for high-rpm use

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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

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Rotary Engine
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Rotary Engine Operation
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Rotary Engine Animation

• http//www.animatedengines.com/wankel.shtml

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Piston Displacement

• Volume the piston displaces as it travels from
  BDC to TDC
• Found by comparing cylinder diameter and piston
  stroke
• Piston displacement formula

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Bore and Stroke
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Piston Displacement

• If an engine has a bore of 4 and a stroke of 3,
  what is its piston displacement?

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Compression Ratio

• This engine has eight times the volume at BDC,
  producing an 81 compression ratio

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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

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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
• 130180 psi (9001200 kPa)
• Diesel engine compression pressure
• 250400 psi (17002800 kPa)

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Horsepower

• One horsepower equals 33,000 ft lb of work per
  minute

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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

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Engine Efficiency