1.What is the firing order of a four stroke engine?
3 cylinders: 1-2-3
4 cylinders: 1-3-4-2 / 1-2-4-3 / 1-3-2-4

5 cylinders: 1-2-4-5-3

6 cylinders: 1-5-3-6-2-4 / 1-6-5-4-3-2 / 1-2-3-4-5-6 / 1-4-2-5-3-6

7 cylinders: 1-3-5-7-2-4-6
8 cylinders: 1-8-4-3-6-5-7-2 / 1-8-7-2-6-5-4-3 / 1-3-7-2-6-5-4-8 / 1-5-4-8-7-2-6-3 / 1-6-2-5-8-3-7-4

10 cylinders: 1-10-9-4-3-6-5-8-7-2 / 1-6-5-10-2-7-3-8-4-9

12 cylinders: 1-7-5-11-3-9-6-12-2-8-4-10

16 cylinders: 1-12-8-11-7-14-5-16-4-15-3-10-6-9-2-13

2.What is the difference between a S.I and C.I engine?
1. Type of cycle: 
 S.I - Otto cycle
 C.I - Diesel cycle
2. Type of fuel:   
 S.I - Petrol
 C.I - Diesel
3. Type of ignition:
 S.I - Ignite by spark plug
 C.I - Self-ignite by high pressure
4. Compression ratio:
 S.I - 6~10
 C.I - 16~20
5. Weight:
 C.I engines are heavier than S.I engines because higher pressure inside the engine.
6. Speed:
 S.I engines run at higher speeds than C.I engines
7. Thermal efficiency:
 C.I engines have higher thermal efficiency than S.I engines due to the higher pressure.


3.Is there any difference between a S.I and C.I piston if so what?
In most C.I engines, the combustion chamber is in the top of the piston,  rather than the S.I engines in the cylinder head. C.I pistons also longer and heavier than S.I pistons.

   C.I piston                        S.I piston


4.What year was the diesel engine invented and by whom?

Diesel engine was invented at 1892 by German inventor Rudolf Diesel.


5.What is the purpose of the oil jet on the connecting rod, and where does it spray?
The oil jet lines up with the oil hole in the crankpin once on each revolution of the crankshaft. When this occurs, a squirt of oil is directed onto the cylinder walls, also lubricates the piston pin.

6.On the connecting rod where is the big end and little end?
 Big end - The crankpin end. Little end - The piston end.

7.What is the purpose of the thrush washers on the crankshaft?
Thrust washers are long-wearing flat bearings to keep crankshaft rotates in position.

8.On a diesel engine whats the difference between direct injection and a indirect injection type?
Direct injection: Fuel is injected directly into the combustion chamber in the piston head.
Indirect injection: Fuel not inject into the main combustion space, instead, the fuel is injected into a small separate chamber.

9.Explan the term valve timing?
Lead - intake valve opens before TDC and exhaust valve opens before BDC.
Lag - intake valve closes after BDC and exhaust valve closes after TDC.

Overlap - intake and exhaust valves are both open for a few degrees around TDC of the exhaust stoke.

10.Why do we have valve clearance?
Because the valve train gets hot when engine is running, needs some clearance to expand, otherwise the valve will not shut properly. May cause a gas leak, or a valve burn.