1. Intake Stroke: Air is drawn into the cylinders. Unlike gasoline engines, there's no fuel injected during this stage.
2. Compression Stroke: The piston compresses the air to a very high pressure and temperature (typically around 500°C or 932°F). This is crucial; the heat is what ignites the fuel.
3. Fuel Injection: Just before the top of the compression stroke, precisely timed fuel injectors spray a fine mist of diesel fuel into the compressed air within the cylinder.
4. Combustion/Power Stroke: The extremely hot, compressed air ignites the finely atomized fuel spontaneously. This combustion generates a powerful explosion, pushing the piston downward.
5. Exhaust Stroke: The piston moves upward, expelling the burnt gases from the cylinder.
Key Differences from Gasoline Engines:
* No spark plugs: Diesel engines don't use spark plugs to ignite the fuel. The heat of compression is sufficient.
* Higher Compression Ratio: Diesel engines have much higher compression ratios than gasoline engines, necessary to achieve the high temperatures needed for auto-ignition.
* Fuel Injection Timing: Precise fuel injection timing is critical for efficient and clean combustion. The timing is controlled by the engine's computer (Electronic Control Module or ECM).
In short, the Dodge Cummins engine fires due to the heat generated by compressing air, which then ignites the injected diesel fuel. This self-ignition process is the defining characteristic of diesel engines.
