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4

The knocking in spark ignition engines can be reduced by

A. Retarding the spark

B. Increasing the engine speed

C. Both (A) and (B)

D. None of these

Correct Answer :

C. Both (A) and (B)


Related Questions

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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

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

A mixture containing 65% of iso-octane and 35% of normal heptane will have

A. Cetane number 65

B. Octane number 65

C. Cetane number 35

D. Octane number 35

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4

The volumetric efficiency of a well designed engine may be

A. 30 to 40 %

B. 40 to 60 %

C. 60 to 70 %

D. 75 to 90 %

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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

If petrol is used in a diesel engine, then

A. Low power will be produced

B. Efficiency will be low

C. Higher knocking will occur

D. Black smoke will be produced

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4

The advancing of spark timing in spark ignition engines will _________ knocking tendency.

A. Increase

B. Reduce

C. Not effect

D. None 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 object of supercharging the engine is

A. To reduce mass of the engine per brake power

B. To reduce space occupied by the engine

C. To increase the power output of an engine when greater power is required

D. All of the above

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4

Flash point of fuel oil is

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. Temperature at which 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

Combustion in compression ignition engines is

A. Homogeneous

B. Heterogeneous

C. Both (A) and (B)

D. Laminar

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4

In order to mix air and petrol in the required proportion and to supply it to the engine during suction stroke, then _________ is employed.

A. Fuel pump

B. Injector

C. Carburettor

D. None of these

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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

Morse test is used to determine the I.P. of a

A. Single cylinder petrol engine

B. Four stroke engine

C. Single cylinder diesel engine

D. Multi cylinder engine

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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 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 turbine of the turboprop engine is __________ that of the turbojet engine.

A. Same as

B. Smaller than

C. Bigger than

D. None of these

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4

In a petrol engine, the fuel supplied to the engine cylinder is mixed with required quantity of air and the mixture is ignited with a

A. Fuel pump

B. Fuel injector

C. Spark plug

D. None of these

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4

The thermal efficiency of diesel engines is about

A. 15 %

B. 30 %

C. 50 %

D. 70 %

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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

The process of breaking up or a liquid into fine droplets by spraying is called

A. Vaporisation

B. Carburetion

C. Ionisation

D. Atomisation

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4

The purpose of testing an internal combustion engine is

A. To determine the information, which cannot be obtained by calculations

B. To conform the data used in design, the validity of which may be doubtful

C. To satisfy the customer regarding the performance of the engine

D. All of the above

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4

The accumulation of carbon in a cylinder results in increase of

A. Clearance volume

B. Volumetric efficiency

C. Ignition time

D. Effective compression ratio

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4

The thermal efficiency of a diesel cycle having fixed compression ratio, with increase in cut-off ratio will

A. Increase

B. Decrease

C. Be independent

D. May increase or decrease depending on other factors

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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

A petrol engine has compression ratio from

A. 6 to 10

B. 10 to 15

C. 15 to 25

D. 25 to 40

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4

Which of the following is not an interns combustion engine?

A. 2-stroke petrol engine

B. 4-stroke petrol engine

C. Diesel engine

D. Steam turbine

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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

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 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