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

6.2.1: V-engine layout
6.2.2: In line (straight) engine layout

To determine the firing order of a four-cylinder petrol engine, you can:

1. Remove the tappet cover and identify the intake and exhaust valves.
2. Rotate the engine in the direction it turns (clockwise for most engines).
3. Observe which set of valves operates to establish the inlet stroke and exhaust stroke.
4. The order in which these strokes occur will give the firing order.
5. Alternatively, you can remove the distributor cap and ensure the engine turns in the correct direction, then trace the firing order by following the HT leads from the rotor.

6.4.1 Four-cylinder in-line engine: 1, 3, 4, 2 or 1, 2, 4, 3
6.4.2 V6-cylinder engine: 1, 4, 2, 5, 3, 6 or 1, 2, 3, 4, 5, 6 or 1, 4, 5, 3, 2, 6

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

1. More power and boost is obtained from an engine with the same capacity.
2. Improved fuel consumption compared to naturally aspirated engines.

6.6.1 Boost: Refers to the increase in manifold pressure generated by the turbocharger in the intake, which exceeds the normal atmospheric pressure.
6.6.2 Turbo lag: This is the delay experienced between pressing the accelerator and the turbocharger kicking in, commonly due to the time taken for the turbo to spool up.

The waste gate diverts exhaust gases away from the turbine to regulate the turbine speed and consequently manage boost pressure.

The oil cooler helps to prevent overheating by circulating oil that lubricates the turbocharger bearings and other components, maintaining optimal operating temperatures.