Explain the difference between petrol/diesel and four/two stroke engines, and identify the functions of engine components and their firing orders.

here are the answers to your engine questions:

Q5: Explain the difference between a petrol and a diesel engine (2mrks)
A petrol engine uses a spark plug to ignite a compressed air-fuel mixture. A diesel engine compresses air to a very high temperature, then injects fuel which ignites spontaneously due to the heat (compression ignition).

Q6: Explain the difference between a four and a two stroke engine (2mrks)
A four-stroke engine completes one power cycle in four piston strokes (intake, compression, power, exhaust) and two crankshaft revolutions, using separate valves. A two-stroke engine completes one power cycle in two piston strokes and one crankshaft revolution, typically using ports in the cylinder walls instead of complex valve trains.

Q7: True (T) or False (F)
a: The function of a crankshaft is to change the engine movement (T / F) (1 mrk)

• T b: The function of a camshaft is to control the movement of a crankshaft (T / F) (1 mrk)
• F c: Exhaust manifold is to allow the burnt (exhaust) gases out of the combustion chamber of an engine (T / F) (1 mrk)
• T d: Intake manifold allows the fuel/air mixture into the combustion chamber of an engine (T / F) (1mrk)
• T

Q8: Complete the following sentences: (6 mrks)
a: Firing order of a four cylinder engine is 1-3-4-2
b: Firing order of a six cylinder engine is 1-5-3-6-2-4
c: Running mate of number one piston in a four cylinder engine is 4
d: Running mate of number two piston is 3
e: Running mate of number three is 2
f: Running mate of number four is 1

Q9: Explain how the tappets or valve clearances are adjusted according to the firing order of a four cylinder engine (4 mrks)
Valve clearances are adjusted when the piston of a cylinder is at Top Dead Center (TDC) on its compression stroke, meaning its valves are fully closed. This is determined by observing its running mate cylinder. When a cylinder's running mate is at TDC overlap (exhaust valve closing, intake valve opening), the cylinder itself is at TDC compression, and its valve clearances can be adjusted.

Here are the adjustments based on the provided table, assuming a common 4-cylinder engine where 1 and 4 are running mates, and 2 and 3 are running mates:

	Valve clearance adjustments
1: Overlap number 4 cylinder	Adjust: Cylinder 1
2: Overlap number 2 cylinder	Adjust: Cylinder 3
3: Overlap number 1 cylinder	Adjust: Cylinder 4
4: Overlap number 3 cylinder	Adjust: Cylinder 2