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

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

4

# The mean effective pressure obtained from engine indicator indicates the

Maximum pressure developed

Minimum pressure

Instantaneous pressure at any instant

Average pressure

4

Increase

Reduce

Not effect

None of these

4

0

50

100

120

4

Cetane number 65

Octane number 65

Cetane number 35

Octane number 35

4

14.6 : 1

18.5 : 1

20.4 : 1

22.6 : 1

4

# A stoichiometric air-fuel ratio is

Chemically correct mixture

Lean mixture

Rich mixture for idling

4

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

Mechanical efficiency

Overall efficiency

Indicated thermal efficiency

Volumetric efficiency

4

# The output of a diesel engine can be increased without increasing the engine revolution or size in following way

Feeding more fuel

Heating incoming air

Scavenging

Supercharging

4

# The knocking in diesel engines may be prevented by

Reducing the delay period

Raising the compression ratio

Increasing the inlet pressure of air

All of these

4

Up to 35%

Up to 50%

Up to 75%

Up to 100%

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

# The cam shaft of a four stroke I.C. engine running at 1500 rpm will run at

1500 rpm

750 rpm

3000 rpm

Any value independent of engine speed

4

# The ratio of the volume of charge admitted at N.T.P. to the swept volume of the piston is called

Mechanical efficiency

Overall efficiency

Volumetric efficiency

Relative efficiency

4

# The knocking in spark ignition engines can be reduced by

Retarding the spark

Increasing the engine speed

Both (A) and (B)

None of these

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

It is properly designed

Best quality fuel is used

Cannot work as it is impossible

Flywheel size is proper

4

0

50

100

120

4

# For the same compression ratio

Otto cycle is more efficient than the Diesel

Diesel cycle is more efficient than Otto

Both Otto and Diesel cycles are, equally efficient

Compression ratio has nothing to do with efficiency

4

# Pick up the wrong statement about supercharging

Supercharging reduces knocking in diesel engines

There can be limited supercharging in petrol engines because of detonation

Supercharging at high altitudes is essential

Supercharging results in fuel economy

4

# A diesel engine as compared to petrol engine (both running and rated load) is

More efficient

Less efficient

Equally efficient

Other factors will decide it

4

# A diesel engine, during suction stroke, draws

Air only

Diesel only

A mixture of diesel and air

None of these

4

# In order to eliminate knocking in compression ignition engines, there should be

Short delay period

Late auto-ignition

Low compression ratio

High self ignition temperature of fuel

4

# An hmh flame speed is obtained in diesel engine when air fuel ratio is

Uniform throughout the mixture

Chemically correct mixture

4

# Diesel as compared to petrol is

Highly ignitable

More difficult to ignite

Less difficult to ignite

None of these

4

Remain same

Decrease

Increase

None of these

4

# Scavenging air in diesel engine means

Air used for combustion sent under pressure

Forced air for cooling cylinder

Burnt air containing products of combustion

Air used for forcing burnt gases out of engine's cylinder during the exhaust period

4

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

Beginning of suction stroke

End of suction stroke

Beginning of exhaust stroke

End of exhaust stroke

4

Diesel engines

Gas turbines

Petrol engines

Aircraft engines

4

# The accumulation of carbon in a cylinder results in increase of

Clearance volume

Volumetric efficiency

Ignition time

Effective compression ratio

4

10 bar

20 bar

25 bar

35 bar