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4

The increase of cooling water temperature in petrol engine will __________ the knocking tendency.

A. Not effect

B. Decrease

C. Increase

D. None of these

Correct Answer :

C. Increase


Related Questions

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4

The combustion in compression ignition engines is

A. Homogeneous

B. Heterogeneous

C. Both (A) and (B)

D. None of these

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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

Which of the following statement is wrong?

A. A four stroke cycle engine develops twice the power as that of a two stroke cycle engine

B. For the same power developed, a four stroke cycle engine is lighter, less bulky and occupies less floor area

C. The petrol engines are costly than diesel engines

D. All of the above

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4

The air-fuel ratio in petrol engines is controlled by

A. Controlling valve opening/closing

B. Governing

C. Injection

D. Carburetion

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4

Solid fuel fabricated into various small shapes, which are assembled to form fuel elements, is in the form of

A. Plates

B. Pallets

C. Pins

D. All of these

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4

In a typical medium speed 4-stroke cycle diesel engine the inlet valve

A. Opens at 20° before top dead center and closes at 35° after the bottom dead center

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

C. Opens at 10° after top dead center and closes 20° before the bottom dead center

D. May open or close anywhere

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4

In the crankcase method of scavenging, the air pressure is produced by

A. Supercharger

B. Centrifugal pump

C. Natural aspirator

D. Movement of engine piston

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4

High speed compression engines operate on

A. Otto cycle

B. Diesel cycle

C. Dual combustion cycle

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

Pre-ignition is caused by the spontaneous combustion of the mixture before the end of the compression stroke, and is due to

A. Cylinder walls being too hot

B. Overheated spark plug points

C. Red hot carbon deposits on cylinder walls

D. Any one of these

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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 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

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 pressure inside the cylinder is _________ the atmospheric pressure during the exhaust stroke.

A. Equal to

B. Below

C. Above

D. None of these

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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

The air standard efficiency of an Otto cycle compared to diesel cycle for the given compression ratio is

A. Same

B. Less

C. More

D. More or less depending on power rating

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4

In a four stroke cycle petrol engine, the inlet valve

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

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

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

D. May open or close anywhere

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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 thermal efficiency of diesel engines on weak mixtures is

A. Unaffected

B. Lower

C. Higher

D. Dependent on other factors

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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 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 mean effective pressure obtained from engine indicator indicates the

A. Maximum pressure developed

B. Minimum pressure

C. Instantaneous pressure at any instant

D. Average pressure

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4

It the temperature of intake air in IC engines is lowered, then its efficiency will

A. Increase

B. Decrease

C. Remain same

D. Increase up to certain limit and then decrease

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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

If the temperature of intake air in internal combustion engine increases, then its efficiency will

A. Remain same

B. Decrease

C. Increase

D. None of these

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4

The voltage required to produce a spark across the gap, between the sparking points is

A. 2000 to 4000 volts

B. 4000 to 6000 volts

C. 6000 to 10,000 volts

D. 10,000 to 12,000 volts

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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

Which of the following is false statement? Excess quantities of sulphur in diesel fuel are Objectionable because it may cause the following

A. Piston ring and cylinder wear

B. Formation of hard coating on piston skirts

C. Oil sludge in the engine crank case

D. Detonation

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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

A fuel of an octane number rating of 75 matches in knocking intensity as a mixture of

A. 75% iso-octane and 25% normal heptane

B. 75% normal heptane and 25% iso-octane

C. 75% petrol and 25% diesel

D. 75% diesel and 25% petrol