4

1 sec

0.1 sec

0.01 sec

0.001 sec

D. 0.001 sec

4

# In compression ignition engines, swirl denotes a

Haphazard motion of the gases in the chamber

Rotary motion of the gases in the chamber

Radial motion of the gases in the chamber

None of the above

4

6 kg/cm

12 kg/cm

20 kg/cm

35 kg/cm

4

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

Increase

Decrease

Remain same

Increase up to certain limit and then decrease

4

# The two reference fuels used for cetane rating are

Cetane and iso-octane

Cetane and alpha-methyl naphthalene

Cetane and normal heptane

4

10 bar

20 bar

25 bar

35 bar

4

# Which of the following statement is correct regarding petrol engines?

A fine fuel spray mixed with air is ignited by the heat of compression which is at a high pressure

The fuel supplied to the engine cylinder is mixed with necessary amount of air and the mixture in ignited with the help of a spark plug

The fuel is first evaporated after passing through a carburettor and is mixed with air before ignition

All of the above

4

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

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

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

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

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

4

180°

125°

235°

200°

4

# A heat engine utilises the

Calorific value of oil

Low heat value of

High heat value of oil

Mean heat value of oil

4

Equal to

Less than

Greater than

None of these

4

Cetane number

Octane number

Calorific value

All of these

4

1/2

1

2

4

4

# In a four stroke cycle diesel engine, the exhaust valve

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

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

May open and close anywhere

4

25 %

50 %

70 %

100 %

4

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

Prevent sparking across the gap between the points

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

Both (A) and (B)

None of the above

4

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

40% cetane and 60% alpha methyl naphthalene

40% alpha methyl naphthalene and 60% cetane

40% petrol and 60% diesel

40% diesel and 60% petrol

4

# A carburettor is used to supply

Petrol, air and lubricating oil

Air and diesel

Petrol and lubricating oil

Petrol and air

4

5-10 kg/cm²

20-25 kg/cm²

60-80 kg/cm²

90-130 kg/cm²

4

# The reason for supercharging in any engine is to

Increase efficiency

Increase power

Reduce weight and bulk for a given output

Effect fuel economy

4

# The increase in intake temperature of internal combustion engines will _________ efficiency.

Have no effect on

Increase

Decrease

None of these

4

Otto cycle

Joule cycle

Rankine cycle

Stirling cycle

4

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

Supercharger

Centrifugal pump

Natural aspirator

Movement of engine piston

4

# The compensating jet in a carburettor supplies almost constant amount of petrol at all speeds because the

Jet area is automatically varied depending on the suction

The flow from the main jet is diverted to the compensating jet with increase in speed

The diameter of the jet is constant and the discharge coefficient is invariant

Flow is produced due to the static head in the float chamber

4

# Which of the following statement is correct?

Compression ratio for petrol engines varies from 6 to 10

Higher compression ratio in diesel engines results in higher pressures

Petrol engines work on Otto cycle

All of the above

4

# Pick up the wrong statement

2-stroke engine can run in any direction

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

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

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

4

# The increase of efficiency of a compression ignition engine, as the load decreases, is due to

Higher maximum temperature

Qualitative governing

Quantitative governing

Hit and miss governing

4

Equal to

One-half

Twice

Four-times

4

500-1000°C

1000-1500°C

1500-2000°C

2000-2500°C

4

10 bar

100 bar

150 bar

500 bar