x Chapter 6 Engine Classification, Parts Identification . . . . . . . . . . .123 Cycle Classifications ..................................................... 123 Four-Stroke Cycle Engine .............................................. 123 Two-Stroke Cycle Engine ............................................... 123 Valve Classifications ..................................................... 125 L-Head, T-Head, and F-Head Designs ........................ 125 I-Head Design .................................................................... 126 Combustion Chamber Design Classifications .................................................. 130 Detonation and Preignition .......................................... 130 Ricardo Combustion Chamber .................................... 130 Hemispherical Combustion Chamber ....................... 130 Wedge Combustion Chamber ...................................... 131 Cylinder Classifications .............................................. 131 Inline Engine ..................................................................... 131 V-Type Engine ................................................................... 132 Horizontally Opposed Engines .................................... 132 Firing Order ....................................................................... 132 Cooling Classifications ............................................... 132 Fuel Classifications ........................................................ 133 E85 ........................................................................................ 133 Biodiesel .............................................................................. 133 Two-Stroke and Four-Stroke Cycle Diesel Engines ....................................................... 134 Natural Gas ........................................................................ 135 Other Engine Designs .................................................. 135 Rotary Engines .................................................................. 135 Atkinson- and Miller-Cycle Engines ........................... 136 Variable Compression Engines .................................... 137 New Technologies ........................................................... 138 Hybrid Vehicles ................................................................. 138 All-Electric Vehicles ........................................................ 141 Fuel Cell Vehicles ............................................................. 142 Identification and Classification .......................... 142 Chapter 7 Engine Size and Performance Measurements. . . . . . . . . . . . . . . .147 Horsepower ........................................................................ 147 Horsepower Formula ...................................................... 148 Types of Horsepower....................................................... 148 Torque .................................................................................... 151 Engine Efficiency ............................................................ 151 Thermal Efficiency .......................................................... 151 Mechanical Efficiency..................................................... 152 Volumetric Efficiency ..................................................... 152 Engine Size (Displacement) .................................... 153 Square and Over-Square Engines ................................ 154 Compression Ratio ........................................................ 155 Chapter 8 Electrical System Fundamentals . . . . . . . . . . . . . . . .159 Basic Electricity ............................................................... 159 Matter .................................................................................. 159 Electric Current ................................................................ 161 Ohm’s Law .......................................................................... 164 Electric Circuits ............................................................... 164 Series Circuit ..................................................................... 164 Parallel Circuit .................................................................. 165 Series-Parallel Circuit ..................................................... 166 Vehicle Chassis as Ground Wire .................................. 166 Frequency ............................................................................ 166 Magnetism ........................................................................... 167 Magnetic Domains .......................................................... 167 Lines of Force .................................................................... 167 Principles of Magnetism ................................................ 168 Electromagnetism .......................................................... 168 Basic Automotive Electronics ................................ 169 Diodes .................................................................................. 169 Transistors ......................................................................... 170 Common Electrical Devices .......................................... 171 Chapter 9 Computer Systems . . . . . . . . . . . .177 Computers on Modern Vehicles ............................ 177 Electronic Control Module ....................................... 179 Central Processing Unit ................................................. 179 Permanent Computer Memory .................................... 179 Temporary Computer Memory .................................... 180 Sleep Mode ......................................................................... 180 Computer Control Operation ................................. 180 Open and Closed Loop Operation .............................. 181 Engine Protection ............................................................ 181 System Monitors ............................................................... 181 Multiplexing ....................................................................... 181 Wires and Fiber-Optic Cables ...................................... 183 ECM-Driver Communications ..................................... 183 ECM-Technician Communications ............................ 183