4842 Automotive Engines questions 3

1.What is the firing order of a four stroke engine?
2.What is the difference between a S.I and C.I engine?
3.Is there any difference between a S.I and C.I piston if so what?
4.What year was the diesel engine invented and by whom?
5.What is the purpose of the oil jet on the connectng rod, and where does it spray?
6.On the connecting rod where is the big end and little end?
7.What is the purpose of the thrush washers on the crankshaft?
8.On a diesel engine whats the difference between direct injection and a indirect injection type?
9.Explan the term valve timming?
10.Why do we have valve clearance?




1. Basically 1342 but, each engine has a different firing order. But on the twin cam mazda engines we are working on when the 1st cylinder is at TDC the 2nd and 3rd are at BDC and the 4th is at TDC. So when the 1st cylinder is travelling upward toward TDC it is on the compression stroke while the 4th cylinder that is travelling toward tdc is exhausting. Mean while the 2nd cylinder is on a power stroke the 3rd cylinder is on intake.

2. Spark ignition engines use spark plugs to ignite the fuel where as a compression ignition engine relies on the high compression to ignite the fuel.


3. The pistons in a C.I engine are shaped alot differently to the S.I engine. Their piston crowns are are shaped differently due to the fact that these engines rely on compression. Also the compression engine pistons are made stronger due to being under higher stresses. 

4. The diesel engine, well the C.I. engine was invented by Herbert Ackroyd-Stuart in 1890.

5. The oil jet on the con rod sprays oil into the cylinder while the piston is travelling toward TDC. It does this because there is alot of friction created in the cylinder. So the oil is used as a lubricant to keep friction to a minimum.

6. On the conrod the big end is connected to the crankshaft and the little end is connected to the piston via the gudgeon pin.

7. The thrust bearing stops the end play in the crankshaft. Because the engine is turning clockwise it automatically forced the crankshaft forward. so the 'spacers' stop the play.

8.