IC Engines Practice Set-1

1. The mean effective pressure obtained from engine indicator indicates the

Average pressure

Minimum pressure

Maximum pressure developed

Instantaneous pressure at any instant

2. Pick up the wrong statement about supercharging

Supercharging results in fuel economy

There can be limited supercharging in petrol engines because of detonation

Supercharging reduces knocking in diesel engines

Supercharging at high altitudes is essential

3. In compression ignition engines, swirl denotes a

Radial motion of the gases in the chamber

None of the above

Rotary motion of the gases in the chamber

Haphazard motion of the gases in the chamber

4. The air requirement of a petrol engine during starting compared to theoretical air required for complete combustion is

Less

Same

More

May be more or less depending on engine capacity

5. Detonation is harmful due to

High intensity of knock causes crankshaft vibration and the engine runs rough

Excessive turbulence which removes most of the insulating gas boundary layer from the cylinder walls

None of the above

Increase in the rate of heat transfer, there is a reduction in the power output and efficiency of the engine

6. In a four stroke cycle petrol engine, the compression

Starts at 40° before bottom dead centre and ends at 30° after bottom dead centre

Starts at 40° after bottom dead centre and ends at 30° before top dead centre

May start and end anywhere

Starts at bottom dead centre and ends at top dead centre

7. The operation of forcing additional air under pressure in the engine cylinder is known as

Scavenging

Turbulence

Supercharging

Pre-ignition

8. Which one of the following engines will have heavier flywheel than the remaining ones?

30 kW two-stroke petrol engine running at 1500 r.p.m.

30 kW four-stroke petrol engine running at 1500 r.p.m.

30 kW two-stroke diesel engine running at 750 r.p.m.

30 kW four-stroke diesel engine running at 750 r.p.m.

9. Pour point of fuel oil is the

Indicated by 90% distillation temperature i.e., when 90% of sample oil has distilled off

It catches fire without external aid

Minimum temperature to which oil is heated in order to give off inflammable vapours in sufficient quantity to ignite momentarily when brought in contact with a flame

Temperature at which it solidifies or congeals

10. Compression ratio of I.C. Engines is

Swept volume/cylinder volume

Volume displaced by piston per stroke and clearance volume in cylinder

Ratio of pressure after compression and before compression

The ratio of volumes of air in cylinder before compression stroke and after compression stroke

IC Engines Practice Set-1

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