Internal Combustion Engine Basics

Basic Components

• Cylinders: Where combustion takes place
• Pistons: Move up and down in cylinders, driven by explosive force of combustion
• Crankshaft: Converts up-and-down motion of pistons into rotary motion
• Camshaft: Operates valves that allow air and fuel into cylinders and exhaust gases out
• Valves: Control flow of air and fuel into cylinders and exhaust gases out

Four-Stroke Cycle

1. Intake: Air and fuel enter cylinder through intake valve
2. Compression: Intake valve closes, piston moves up, compressing air and fuel
3. Power: Spark plug ignites air and fuel, causing piston to move down
4. Exhaust: Exhaust valve opens, piston moves up, pushing exhaust gases out

Engine Types

• Spark Ignition (SI) Engine: Uses spark plug to ignite air and fuel (e.g., gasoline engine)
• Compression Ignition (CI) Engine: Uses heat generated by compression to ignite air and fuel (e.g., diesel engine)

Fuel Systems

• Carburetor: Mixes air and fuel for older engines
• Fuel Injection: Sprays fuel into cylinders at precise times for modern engines

Emissions and Efficiency

• Emissions: Harmful gases released by engine, including CO, HC, NOx, and PM
• Fuel Efficiency: Measured by miles per gallon (mpg) or liters per 100 kilometers (L/100km)
• Emissions Control: Systems to reduce emissions, such as catalytic converters and exhaust gas recirculation

Additional Concepts

• Torque: Rotational force of engine, measured in Newton-meters (Nm) or foot-pounds (ft-lb)
• Horsepower: Unit of measurement for engine power, calculated from torque and engine speed
• Engine Displacement: Total volume of all cylinders, measured in liters (L) or cubic inches (in³)