6.1 What do you understand by static balancing of a crankshaft?
6.2 Identify the cylinder layouts as illustrated in FIGURES 6.2.1 and 6.2.2 below - NSC Mechanical Technology Automotive - Question 6 - 2018 - Paper 1
Question 6
6.1 What do you understand by static balancing of a crankshaft?
6.2 Identify the cylinder layouts as illustrated in FIGURES 6.2.1 and 6.2.2 below.
6.3 Explain how... show full transcript
Worked Solution & Example Answer:6.1 What do you understand by static balancing of a crankshaft?
6.2 Identify the cylinder layouts as illustrated in FIGURES 6.2.1 and 6.2.2 below - NSC Mechanical Technology Automotive - Question 6 - 2018 - Paper 1
Step 1
What do you understand by static balancing of a crankshaft?
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Answer
Static balancing of a crankshaft refers to the condition where the mass is uniformly distributed around its rotational axis. This means that when the crankshaft is at rest, it should not tilt or rotate due to uneven mass distribution. Proper static balancing reduces vibrations during engine operation and ensures smooth performance.
Step 2
Identify the cylinder layouts as illustrated in FIGURES 6.2.1 and 6.2.2 below.
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Answer
The layout in FIGURE 6.2.1 is a V-engine layout, while the layout in FIGURE 6.2.2 is an inline (straight) engine layout.
Step 3
Explain how you will determine the firing order of a four-cylinder petrol engine if it is not marked on the crankshaft pulley and the manual is not available.
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Answer
To determine the firing order of a four-cylinder petrol engine, you can follow these steps:
Remove the tappet cover to identify the intake and exhaust valves.
Rotate the engine in the direction it turns (usually clockwise).
Observe the order in which the inlet and exhaust valves open.
Note that the power stroke occurs when the valve for the respective cylinder is closed.
Alternatively, if accessible, remove the distributor cap to ensure correct orientation with respect to the engine’s rotation and trace the firing order using the high tension (HT) leads.
Step 4
State the firing order of the following types of engines:
4-cylinder in-line engine
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The firing order for a four-cylinder in-line engine can be either 1-3-4-2 or 1-2-4-3.
Step 5
V6-cylinder engine
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The firing order for a V6-cylinder engine can be 1-4-2-5-3-6 or 1-2-5-4-3-6.
Step 6
Label parts A–G.
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A – Compressor air inlet
B – Turbine housing
C – Turbine exhaust gas outlet
D – Turbine wheel
E – Turbine exhaust gas inlet
F – Compressed air outlet
G – Compressor wheel
Step 7
State TWO advantages of the turbocharger.
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More power or boost is obtained from an engine with the same capacity.
Improved fuel consumption due to enhanced efficiency in the air-fuel mixture.
Step 8
Explain the following terms:
Boost
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Boost refers to the increase in manifold pressure generated by the turbocharger in the intake, which exceeds the normal atmospheric pressure. This allows for a denser air charge, improving combustion efficiency.
Step 9
Turbo lag
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Turbo lag is the delay experienced when accelerating, as it refers to the time taken for the turbocharger to spool up and deliver increased power. This occurs when there is a delay in pushing the accelerator until the turbo activates.
Step 10
What is the purpose of the waste gate in the turbocharger?
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The waste gate diverts exhaust gases away from the turbine wheel when the desired boost level is reached, preventing over-pressurization and potential damage to the engine.
Step 11
What is the purpose of an oil cooler fitted to a turbocharged engine?
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The oil cooler is used to prevent overheating of the oil that lubricates the turbocharger bearings, ensuring optimal operation and longevity of the turbocharger by maintaining suitable operating temperatures.
