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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

Correct Answer :

B. Reduce


Related Questions

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4

The knocking tendency in spark ignition engines may be decreased by

A. Controlling the air-fuel mixture

B. Controlling the ignition timing

C. Controlling the exhaust temperature

D. Reducing the compression ratio

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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

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4

The air requirement of a petrol engine during starting compared to theoretical air required for complete combustion is

A. More

B. Less

C. Same

D. May be more or less depending on engine capacity

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4

The inlet valve of a four stroke cycle internal combustion engine remains open for

A. 130°

B. 180°

C. 230°

D. 270°

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4

In a typical medium speed 4-stroke cycle diesel engines

A. Exhaust valve opens at 35° before bottom dead centre and closes at 20° after top dead centre

B. Exhaust valve opens at bottom dead centre and closes at top dead centre

C. Exhaust valve opens just after bottom dead centre and closes just before top dead centre

D. May open and close anywhere

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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

Pick up the wrong statement

A. 2-stroke engine can run in any direction

B. In 4-stroke engine, a power stroke is obtained in 4-strokes

C. Thermal efficiency of 4-stroke engine is more due to positive scavenging

D. Petrol engines occupy more space than diesel engines for same power output

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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

The working pressure and temperature inside the cylinder of an internal combustion engine is _________ as compared to a steam engine.

A. Low

B. Very low

C. High

D. Very high

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4

The basic requirement of a good combustion chamber is

A. Minimum turbulence

B. Low compression ratio

C. High thermal efficiency and power output

D. Low volumetric efficiency

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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

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

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

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

In a four stroke cycle, the minimum temperature inside the engine cylinder occurs at the

A. Beginning of suction stroke

B. End of suction stroke

C. Beginning of exhaust stroke

D. End of exhaust stroke

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4

In a four stroke cycle diesel engine, the compression

A. Starts at 40° after bottom dead centre and ends at 10° before top dead centre

B. Starts at 40° before top dead centre and ends at 40° after top dead centre

C. Starts at top dead centre and ends at 40° before bottom dead centre

D. May start and end anywhere

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4

If the intake air temperature of I.C. engine increases, its efficiency will

A. Increase

B. Decrease

C. Remain same

D. None of these

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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

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

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 ratio of indicated thermal efficiency to the corresponding air standard cycle efficiency is called

A. Net efficiency

B. Efficiency ratio

C. Relative efficiency

D. Overall efficiency

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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

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

A supercharged engine as compared to an ordinary engine

A. Is lighter

B. Requires smaller foundations

C. Consumes less lubricating oil

D. All 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

Installation of supercharger on a four cycle diesel engine can result in the following percentage increase in power

A. Up to 35%

B. Up to 50%

C. Up to 75%

D. Up to 100%

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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

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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 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 injector nozzle of a compression ignition engine is required to inject fuel at a sufficiently high pressure in order to

A. Inject fuel in a chamber of high pressure at the end of compression stroke

B. Inject fuel at a high velocity to facilitate atomisation

C. Ensure that penetration is not high

D. All of the above