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4

The scavenging efficiency of a four stroke cycle diesel engine is

A. Below 50%

B. Between 50 and 85%

C. Between 85 and 95%

D. Between 95 and 100%

Correct Answer :

D. Between 95 and 100%


Related Questions

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4

The theoretically correct air fuel ratio for petrol engine is of the order of

A. 6 : 1

B. 9 : 1

C. 12 : 1

D. 15 : 1

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4

In a cycle, the spark lasts roughly for

A. 1 sec

B. 0.1 sec

C. 0.01 sec

D. 0.001 sec

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4

A 75 cc engine has following parameter as 75 cc

A. Fuel tank capacity

B. Lube oil capacity

C. Swept volume

D. Cylinder volume

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4

For maximum power generation, the air fuel ratio for a petrol engine for vehicles, is of the order of

A. 9 : 1

B. 12 : 1

C. 15 : 1

D. 18 : 1

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4

Iso-octane (C8H18) has octane number of

A. 0

B. 50

C. 100

D. 120

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4

Antiknock for compression ignition engines is

A. Napthene

B. Tetra ethyl lead

C. Amyl nitrate

D. Hexadecane

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4

A petrol engine, during suction stroke draws

A. Air only

B. Petrol only

C. A mixture of petrol and air

D. None of these

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4

The cam shaft of a four stroke I.C. engine running at 1500 rpm will run at

A. 1500 rpm

B. 750 rpm

C. 3000 rpm

D. Any value independent of engine speed

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4

The magneto in an automobile is basically

A. Transformer

B. D.C. generator

C. Capacitor

D. Magnetic circuit

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4

The working cycle in case of four stroke engine is completed in following number of revolutions of crankshaft

A. 1/2

B. 1

C. 2

D. 4

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4

In an internal combustion engine, the process of removing the burnt gases from the combustion chamber of the engine cylinder is known as

A. Scavenging

B. Detonation

C. Supercharging

D. Polymerisation

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4

The thermal efficiency of a standard Otto cycle for a compression ratio of 5.5 will be

A. 25 %

B. 50 %

C. 70 %

D. 100 %

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4

The operation of forcing additional air under pressure into the engine cylinder is known as

A. Supercharging

B. Carburetion

C. Turbulence

D. Delay period

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4

Compression ratio of I.C. Engines is

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

B. Volume displaced by piston per stroke and clearance volume in cylinder

C. Ratio of pressure after compression and before compression

D. Swept volume/cylinder volume

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4

In a four stroke cycle petrol engine, the charge is ignited at

A. 30° before top dead centre

B. 30° after top dead centre

C. 30° before bottom dead centre

D. 30° after bottom dead centre

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4

The delay period in compression ignition engines depends upon

A. Temperature and pressure in the cylinder at the time of injection

B. Nature of the fuel mixture strength

C. Relative velocity between the fuel injection and air turbulence pressure of residual gases

D. All of the above

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4

The maximum propulsive efficiency of a turbojet engine is at a speed of

A. 1000 km/h

B. 2000 km/h

C. 2400 km/h

D. 3000 km/h

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4

In loop scavenging, the top of the piston is

A. Flat

B. Contoured

C. Slanted

D. Depressed

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4

The knocking in diesel engines may be prevented by

A. Reducing the delay period

B. Raising the compression ratio

C. Increasing the inlet pressure of air

D. All of these

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4

In the opposed piston diesel engine, the combustion chamber is located

A. Above the piston

B. Below the piston

C. Between the pistons

D. There is no such criterion

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4

The higher combustion chamber wall temperature in compression ignition engines will _________ knocking tendency.

A. Increase

B. Reduce

C. Not effect

D. None of these

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4

The octane number of petrol, generally available, is

A. 20 to 40

B. 40 to 60

C. 60 to 80

D. 80 to 100

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4

The brake power (B.P.) of the engine is given by (where W = Brake load or dead load in newtons, l = Length of arm in metres, N = Speed of engine in r.p.m., S = Spring balance reading in newtons, D = Dia. of brake drum in metres, and d = Dia. of rope in metres)

A. B.P = (Wl × 2πN)/60 watts

B. B.P = [(W - S) πDN]/60 watts

C. B.P = [(W - S) π (D + d) N]/60 watts

D. All of these

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4

The air standard efficiency of an I.C. engine is given by (where r = Compression ratio, and γ = Ratio of specific heats)

A. 1 - rγ - 1

B. 1 + rγ - 1

C. 1 - (1/rγ - 1)

D. None of these

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4

The brake power of a diesel engine, keeping other parameters constant, can be increased by

A. Decreasing the density of intake air

B. Increasing the temperature of intake air

C. Increasing the pressure of intake air

D. Decreasing the pressure of intake air

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4

The probability of knocking in diesel engines is increased by

A. High self ignition temperature

B. Low volatility

C. Higher viscosity

D. All of these

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4

The fuel in diesel engine is normally injected at pressure of

A. 5-10 kg/cm²

B. 20-25 kg/cm²

C. 60-80 kg/cm²

D. 90-130 kg/cm²

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4

In order to eliminate knocking in compression ignition engines, there should be

A. Short delay period

B. Late auto-ignition

C. Low compression ratio

D. High self ignition temperature of fuel

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4

If the compression ratio in I.C. engine increases, then its thermal efficiency will

A. Decrease

B. Increase

C. Remain same

D. None of these

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4

By higher octane number of spark ignition fuel, it is meant that the fuel has

A. Higher heating value

B. Higher flash point

C. Lower volatility

D. Longer ignition delay