1. Four Stroke Engines
How does a canon work?

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

3. Mechanical Motion

4. Chemical to Mechanical

5. 1st stroke: Intake stroke
Gasoline and diesel engines have to go through 4 strokes to create power to move the car
the intake valve opens
the piston moves down

6. 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

7. 2nd 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

8. 3rd 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

9. 4th 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

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

11. Interesting Facts
the burning air-fuel mixture can reach ≈1200°C or more
the crankshaft spins ≈750 times per minute at idle
it spins ≈3000 times per minute at freeway speeds
this equals 50 times per second!
the force on the piston during the power stroke is ≈1700kgs
a well maintained engine can last 300,000 km or more!
the design of a 4 stroke engine hasn’t changed very much over the last 100 years