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4

In loop scavenging, the top of the piston is

A. Flat

B. Contoured

C. Slanted

D. Depressed

Correct Answer :

B. Contoured


Related Questions

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4

Theoretically, a four stroke cycle engine should develop _________ power as that of a two stroke cycle engine.

A. Half

B. Same

C. Double

D. Four times

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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 a diesel engine, the fuel is ignited by

A. Spark

B. Injected fuel

C. Heat resulting from compressing air that is supplied for combustion

D. Ignition

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4

The knock in diesel engine occurs due to

A. Instantaneous and rapid burning of the first part of the charge

B. Instantaneous auto ignition of last part of charge

C. Delayed burning of the first part of the charge

D. Reduction of delay period

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4

In diesel engine the diesel fuel injected into cylinder would burn instantly at about compressed air temperature of

A. 250°C

B. 500°C

C. 1000°C

D. 2000°C

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4

Which is more viscous lube oil?

A. SEA 30

B. SAE 50

C. SAE 70

D. SAE 80

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4

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

A. Scavenging

B. Turbulence

C. Supercharging

D. Pre-ignition

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4

The reflectivity depends upon

A. Geometry of the reflector

B. Energy of neutrons

C. Properties of the reflector

D. All of these

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4

A fuel of cetane number 40 has the same ignition quality as a mixture of

A. 40% cetane and 60% alpha methyl naphthalene

B. 40% alpha methyl naphthalene and 60% cetane

C. 40% petrol and 60% diesel

D. 40% diesel and 60% petrol

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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 two reference fuels used for cetane rating are

A. Cetane and iso-octane

B. Cetane and alpha-methyl naphthalene

C. Cetane and normal heptane

D. Cetane and tetra ethyl lead

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4

In a typical medium speed 4-stroke cycle diesel engine

A. Compression starts at 35° after bottom dead center and ends at top dead center

B. Compression starts at bottom dead center and ends at top dead center

C. Compression starts at 10° before bottom dead center and, ends just before top dead center

D. May start and end anywhere

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4

As compared to air standard cycle, in actual working, the effect of variation in specific heats is to

A. Increase maximum pressure and maximum temperature

B. Reduce maximum pressure and maximum temperature

C. Increase maximum pressure and decrease maximum temperature

D. Decrease maximum pressure and increase maximum temperature

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4

The correct mixture strength (by weight) for petrol is about

A. 14.6 : 1

B. 18.5 : 1

C. 20.4 : 1

D. 22.6 : 1

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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

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 gas engine has a swept volume of 300 cm3 and clearance volume of 25 cm3. Its volumetric efficiency is 0.88 and mechanical efficiency is 0.90. The volume of the mixture taken in per stroke is

A. 248 cm3

B. 252 cm3

C. 264 cm3

D. 286 cm3

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4

The fuel air ratio in a petrol engine fitted with suction carburettor, operating with dirty air filter as compared to clean filter will be

A. Higher

B. Lower

C. Remain unaffected

D. None of the above

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4

In a four stroke cycle diesel engine, the exhaust valve

A. Opens at 30° before bottom dead centre and closes at 10° after top dead centre

B. Opens at 30° after bottom dead centre and closes at 10° before top dead centre

C. Opens at bottom dead centre and closes at top dead centre

D. May open and close anywhere

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4

The rating of a diesel engine, with increase in air inlet temperature, will

A. Increase linearly

B. Decrease linearly

C. Increase parabolically

D. Decrease parabolically

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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

Diesel as compared to petrol is

A. Highly ignitable

B. More difficult to ignite

C. Less difficult to ignite

D. None of these

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4

Which of the following does not relate to a spark ignition engine?

A. Ignition coil

B. Spark plug

C. Carburettor

D. Fuel injector

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4

The term scavenging is generally associated with

A. 2-stroke cycle engines

B. 4-stroke cycle engines

C. Aeroplane engines

D. High efficiency engines

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4

When crude oil is heated, then which of the following hydrocarbon is given off first?

A. Kerosene

B. Gasoline

C. Paraffin

D. Natural gas

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4

The fuels in order of decreasing knock tendency for spark ignition engines are

A. Paraffin, aromatic, napthene

B. Paraffin, napthene, aromatic

C. Napthene, aromatics, paraffin

D. Napthene, paraffin, aromatic

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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%

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4

Crankcase explosion in I.C. engines usually occurs as

A. First a mild explosion followed by a bi explosion

B. First a big explosion followed by a mil explosion

C. Both mild and big explosions occurs simultaneously

D. Never occurs

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4

Diesel fuel, compared to petrol is

A. Less difficult to ignite

B. Just about the same difficult to ignite

C. More difficult to ignite

D. Highly ignitable

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4

Which of the following is false statement? Some of the methods used to reduce diesel smoke are as follows

A. Using additives in the fuel

B. Increasing the compression ratio

C. Adherence to proper fuel specification

D. Avoidance of overloading