1. Diesel Engine
The only difference between diesel engine and a four-stroke
gasoline engine is:
No sparkplug on Diesel engine.
Has a higher compression ratio.
(14:1 to 25:1)
Better fuel mileage.

2. Diesel Engine Intake Stroke: Piston moves from TDC to BDC
creating vacuum in the cylinder
Intake valve opens allowing only
air to enter the cylinder and
exhaust valve remains closed

3. Diesel Engine Compression Stroke Both valves stay closed
Piston moves from BDC to TDC,
compressing air to 22:1
Compressing the air to this extent
increases the temperature inside the
cylinder to above 1000 degree F.

4. Diesel Engine Power Stroke Both valves stay closed
When the piston is at the end of
compression stroke(TDC) the injector
sprays a mist of diesel fuel into the
cylinder.
When hot air mixes with diesel fuel
an explosion takes place in the cylinder.
Expanding gases push the piston
from TDC to BDC

5. Diesel Engine Exhaust Stroke Piston moves from BDC to TDC
Exhaust valve opens and the
exhaust gases escape
Intake valve remains closed

6. Diesel Engine
Four Strokes of Diesel Engine