1. Thermodynamics Lab
Group 2
Krishna, Rafsan, Mostafa, Omari, Rohan, Mahesh

2. Closing Fuel entry
Important because it will prevent more fuel leaking into the
carburettor. Not completely safe as some fuel is already inside

3. Engine check
Making sure that it is in the off position

4. Drain the oil

5. Air
Flow
Remove air filter
The filter removes particles from the air before it
flows down into the engine.

6. Remove Exhaust Manifold
This helps reduce engine noise
It much shorter than one found in a car and does not have a catalytic converter
The small hole is allows condensed water from the exhaust emissions to escape

7. Remove Spark plug
This ignites the air fuel mixture inside the piston

8. Remove rocker cover

9. Rockers
These are operated by the pushrods and control the valve positions
The breather tube returns unused fuel to the inlet to improve
efficiency

10. Remove air intake mount

11. Choke
Controls air flow into engine
Open for cold starts so a richer mixture is used
Closed when engine is hot so fuel is used at a more efficient ratio

12. Throttle
Concerned with power production; regulates the
input of the air-fuel mixture

13. Remove side cover

14. Fan
The solenoid magnet creates the current for the spark plug by magnetic induction so
no need for battery. Cord for initial start
Not convenient for large vehicles because large start force needed
There are 2 sparks per cycle, on the 2nd and 4th stroke, the 2nd spark is ‘wasted’

15. Engine Cooling
Air is used for cooling and is sucked in by the fan. The cover is
important because when it is started by hand, the grooves on the fan
and cover connect and therefore the cord can spin the magnet and fan.

16. Engine Cooling
Car engines are cooled by water, which is good because it has a
much higher specific heat capacity however it is much heavier
and would require a radiator as well.

17. Air + fuel
mixed here
Carburettor
Choke restricts air but throttle regulates the mixture for power control.
Fuel is sucked in from the tank by a pressure difference.
Now cars have pumps because it is more controlled, more efficient and there are lower
maintenance costs.

18. Crank Shaft
Cam shaft
Inside the crank case
The diameter ratio is 1:2 so that the cam shaft rotates once when
the crank shaft rotates twice
A small hook splashes oil as the crank shift spins, for lubrication

19. Cylinder Head
The small cavity seen is for the compressed
gases

20. Timing Marks
These allow the cam and crank shaft to be aligned properly
so the different strokes occur at the correct moments

21. Piston rings
These expand and form a seal inside the cylinder to prevent the oil and the fuel
mixture from escaping. The second ring seen here is to scrape the oil back.
They receive the most wear because they are in contact with the cylinder walls.

22. Pushrods
They push the rocker which pushes the valves.
They are not present in cars because they have overhead cams which push the valves
directly. This is because car engines run at high speeds and the rods are liable to bending.
The valves open once each out of synchronisation to prevent the mixture exiting as it enters

23. Cam shaft
Here there is a spring and weight assembly which makes hand starting the engine
easier by opening the exhaust valve slightly. This helps because the compression
stroke is difficult by hand and this reduces the pressure. However, as the engine starts
and the cam shaft begins to spin quickly, the spring no longer has an effect.

24. We then rebuilt it Successfully
You guys can add stuff here about the rebuild, a
few pics with a title. - I have done all the questions

25. Team 2