2. home.howstuffworks.com

3. http://www.carbibles.com/fuel_engine_bible.html

4. INTAKE stroke a.Piston moves DOWNWARD b.Partial VACUUM draws fuel and air mixture through the INTAKE VALVE and into the cylinder c.Intake Valve: –Opens and closes at the correct instant –Streamlined to allow mixture to pass through

5. COMPRESSION stroke a.Both valves CLOSED b.Air/fuel mixture COMPRESSES -RINGS prevent leakage -Force of combustion INCREASES

6. POWER stroke a.Valves remain CLOSED b.SPARK ignites air/fuel mixture c.Violent EXPLOSION drives the piston downward a.Power depends on the FUEL/AIR MIXTURE and the COMPRESSION RATIO a.Compression ratio: The difference in the VOLUME of the cylinder and chamber from BOTTOM DEAD CENTER to TOP DEAD

7. EXHAUST stroke a.Exhaust valve OPENS b.Piston moves UPWARD c.PISTON forces exhaust gasses through exhaust port to the muffler a.Exhaust valve: -Opens and closes at the correct instant -Streamlined to allow exhaust gasses to pass through