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4

The fuel valve in a four stroke cycle diesel engine

A. Opens at 15° after top dead centre and closes at 20° before bottom dead centre

B. Opens at 15° before top dead centre and closes at 20° after top dead centre

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

D. May open and close anywhere

Correct Answer :

B. Opens at 15° before top dead centre and closes at 20° after top dead centre


Related Questions

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4

In a coil ignition system of petrol engines, a condenser is connected across the contact breaker in order to

A. Prevent sparking across the gap between the points

B. Cause more rapid break of the primary current, giving a higher voltage in the secondary circuit

C. Both (A) and (B)

D. None of the above

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4

Pour point of fuel oil is the

A. 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

B. Temperature at which it solidifies or congeals

C. It catches fire without external aid

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

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4

Most high speed compression engines operate on

A. Diesel cycle

B. Otto cycle

C. Dual combustion cycle

D. Special type of air cycle

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4

The specific fuel consumption per BHP hour for diesel engine is approximately

A. 0.15 kg

B. 0.2 kg

C. 0.25 kg

D. 0.3 kg

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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 specific fuel consumption of a petrol engine compared to diesel engine of same H.P. is

A. Same

B. More

C. Less

D. Less or more depending on operating conditions

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4

The minimum cranking speed in case of petrol engine is about

A. Half the operating speed

B. One fourth of operating speed

C. 250 - 300 rpm

D. 60 - 80 rpm

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4

Diesel engine can work on very lean air fuel ratio of the order of 30: 1. A petrol engine can also work on such a lean ratio provided

A. It is properly designed

B. Best quality fuel is used

C. Cannot work as it is impossible

D. Flywheel size is proper

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4

The ratio of the brake power to the indicated power is called

A. Mechanical efficiency

B. Overall efficiency

C. Indicated thermal efficiency

D. Volumetric efficiency

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4

If the compression ratio of an engine working on Otto cycle is increased from 5 to 7, the percentage increase in efficiency will be

A. 2 %

B. 4 %

C. 8 %

D. 14 %

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4

The frictional power (F.P.) is given by

A. F.P. = B.P. - I.P.

B. F.P. = I.P. - B.P.

C. F.P. = B.P./I.P.

D. F.P. = I.P./B.P.

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4

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

A. Fuel pump

B. Fuel injector

C. Governor

D. Carburettor

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4

In a diesel engine, the duration between the time of injection and ignition, is known as

A. Pre-ignition period

B. Delay period

C. Period of ignition

D. Burning period

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4

The spark ignition engines are governed by

A. Hit and miss governing

B. Qualitative governing

C. Quantitative governing

D. Combination of (B) and (C)

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4

Which of the following statements is correct?

A. All the irreversible engines have same efficiency

B. All the reversible engines have same efficiency

C. Both Rankine and Carnot cycles have same efficiency between same temperature limits

D. All reversible engines working between same temperature limits have same efficiency

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4

The size of inlet valve of an engine in comparison to exhaust valve is

A. More

B. Less

C. Same

D. More/less depending on capacity of engine

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4

The air-fuel ratio of the petrol engine is controlled by

A. Carburettor

B. Injector

C. Governor

D. None of these

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4

In order to prevent knocking in spark ignition engines, the charge away from the spark plug should have

A. Low density

B. Low temperature

C. Long ignition delay

D. All of these

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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 theoretically correct mixture of air and petrol is

A. 10 : 1

B. 15 : 1

C. 20 : 1

D. 25 : 1

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4

The exhaust valve in a four stroke cycle petrol engine

A. Opens at 50° before bottom dead centre and closes at 15° after top dead centre

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

C. Opens at 50° after bottom dead centre and closes at 15° before top dead centre

D. May open and close anywhere

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4

The calorific value of gaseous fuels is expressed in terms of

A. kcal

B. kcal/kg

C. kcal/m²

D. kcal/m3

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4

In a four stroke cycle diesel engine, the inlet valve

A. Opens at 20° before top dead centre and closes at 40° after bottom dead centre

B. Opens at 20° after top dead centre and closes at 20° before bottom dead centre

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

D. May open and close anywhere

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4

The correct sequence of the decreasing order of brake thermal efficiency of the three given basic types of engines is

A. Four stroke C.I. engine, four stroke S.I. engine, two stroke S.I. engine

B. Four stroke S.I. engine, four stroke C.I. engine, two stroke S.I. engine

C. Four stroke C.I. engine, two stroke S.I. engine, four stroke S.I. engine

D. Two stroke S.I. engine, four stroke S.I. engine, four stroke C.I. engine

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4

In a typical medium speed, 4-stroke cycle diesel engine

A. Fuel injection starts at 10° before to dead center and ends at 20° after tor dead center

B. Fuel injection starts at top dead center and ends at 20° after top dead center

C. Fuel injection starts at just before top dead center and ends just after top dead center

D. May start and end anywhere

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4

All heat engines utilize

A. Low heat value of oil

B. High heat value of oil

C. Net calorific value of oil

D. Calorific value of fuel

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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

The function of a distributor in a coil ignition system of I.C. engines is

A. To distribute spark

B. To distribute power

C. To distribute current

D. To time the spark

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4

The _________ engines can work on very lean mixture of fuel.

A. Spark ignition

B. Compression ignition

C. Both (A) and (B)

D. None of these

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4

A supercharged engine as compared to an ordinary engine

A. Requires smaller foundation

B. Is lighter

C. Consumes less lubricating oil

D. All of these