1. 1 Four Stroke Engines How does a canon work?

2. 2 Engine Operation Gasoline & diesel engines convert chemical energy into mechanical energy

3. A Stroke… When the piston moves from TDC to BDC, or vice- versa  TDC: Top Dead Center  BDC: Bottom Dead Center  Gasoline and diesel engines have to go through 4 strokes to create power to move the car

4. 4 1 st stroke: Intake stroke  the intake valve opens  the piston moves down

5. 5 Intake Stroke Continued…  As the piston moves down the cylinder…  a mixture of gas and air enters the cylinder  this mixture is 15 parts air to 1 part gas (15:1 air – fuel ratio)  the air & fuel is mixed & delivered by the fuel system – either a carburetor or fuel injection system

6. 6 2 nd Stroke: Compression Stroke  Intake valve closes  Piston moves up the cylinder  When the piston reaches the top of the cylinder, the air & fuel has been squeezed to 150psi

7. 7 3 rd Stroke: Power Stroke  a spark created by the ignition system, jumps the gap at the spark plug & ignites the air/fuel mixture  This causes the burning gases to expand and drive the piston down the cylinder

8. 8 4 th Stroke: Exhaust Stroke Once the piston reaches the bottom of the cylinder from the power stroke…  The exhaust valve opens  The piston moves up  The burnt gases are pushed out of the cylinder

9. 9 Then what happens? After the exhaust stroke, the piston begins moving down on another intake stroke, continually repeating the 4 strokes

10. Lets watch one… http://auto.howstuffworks.com/engine1.htm