4 stroke engine theory
- 2. The 4 Stroke Cycle The 4 strokes • Intake • Compression • Power • Exhaust Engine speed is measured in RPM (revolutions per minute) • The number of times the crank shaft makes one revolution
- 3. Intake Stroke Exhaust valve is closed. Intake valve opens. Piston goes down and atmospheric pressure pushes the air/fuel mixture into cylinder.
- 4. Compression Stroke After piston reaches lowest point in it’s stroke (BDC) it starts to move up. Intake and exhaust valves are closed. The piston compresses air/fuel mixture to just below it’s self ignition point.
- 5. Power Stroke The spark plug fires near the top of the stroke at TDC (Top Dead Center). The piston starts it’s downward stroke turning the crankshaft. Intake and exhaust valves are still closed.
- 6. Exhaust Stroke The exhaust valve opens. The piston starts it’s upward stroke and forces out exhaust gasses (HC, CO, CO2, O2, and NOx).
- 7. Four things engines need to run Air Fuel Compression Ignition
- 8. So…what is air? Air is a mixture of various gas compounds that are completely mixed in the atmosphere
- 9. A little more detail, please… By volume Nitrogen (N2) 78.1% Oxygen (O2) 20.1% Argon (Ar) 0.93% CO2 0.038% Trace gases <0.03%
- 10. I’m still having a little trouble… Ok, let’s say that air is a football field
- 11. How long is Air? N2 would go from goal to 78yd line
- 12. How long is Air? O2 from 78yd line to 99yd line
- 13. Argon would be almost 1yd CO2 would be 1.3 inches All other trace gases would be 1 inch
- 14. Fuel Well, that takes care of air, what is in fuel? Making BP fuel in the Gulf>
- 15. Fuel
- 16. Well, it’s a witches brew… Over 500 other compounds make up gasoline. It’s probably best if you just pay your $3-$4 and don’t ask questions.
- 17. Air and Fuel go in… …what comes out? CO2 H2O Catalytic ConverterNOx
- 18. Whew! My brain hurts! Can we stop now?