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What is the correct answer?

4

For the same compression ratio

A. Otto cycle is more efficient than the Diesel

B. Diesel cycle is more efficient than Otto

C. Both Otto and Diesel cycles are, equally efficient

D. Compression ratio has nothing to do with efficiency

Correct Answer :

A. Otto cycle is more efficient than the Diesel


Related Questions

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4

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

A. Jet area is automatically varied depending on the suction

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

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

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

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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

A diesel engine has

A. 1 valve

B. 2 valves

C. 3 valves

D. 4 valves

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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

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

In a four stroke cycle engine, the sequence of operations is

A. Suction, compression, expansion and exhaust

B. Suction, expansion, compression and exhaust

C. Expansion, compression, suction and exhaust

D. Compression, expansion, suction and exhaust

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4

A supercharged engine as compared to an ordinary engine

A. Requires smaller foundation

B. Is lighter

C. Consumes less lubricating oil

D. All of these

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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 thermal efficiency of a petrol engine is _________ as compared to diesel engine.

A. Same

B. Less

C. More

D. None of these

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4

Pick up the false statement

A. Thermal efficiency of diesel engine is about 34%

B. Theoretically correct mixture of air and petrol is approximately 15:1

C. High speed compression engines operate on dual combustion cycle

D. S.I. engines are quality governed engines

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4

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

A. Higher maximum temperature

B. Qualitative governing

C. Quantitative governing

D. Hit and miss governing

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4

Which of the following is false statement? Some of the methods used to reduce diesel smoke are as follows

A. Using additives in the fuel

B. Increasing the compression ratio

C. Adherence to proper fuel specification

D. Avoidance of overloading

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4

The specific fuel consumption per B.P. hour for a diesel engine is about

A. 0.2 kg

B. 0.25 kg

C. 0.3 kg

D. 0.35 kg

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4

All heat engines utilize

A. Low heat value of oil

B. High heat value of oil

C. Net calorific value of oil

D. Calorific value of fuel

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4

The temperature of interior surface of cylinder wall in normal operation is not allowed to exceed

A. 80°C

B. 120°C

C. 180°C

D. 240°C

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4

Diesel fuel, compared to petrol is

A. Less difficult to ignite

B. Just about the same difficult to ignite

C. More difficult to ignite

D. Highly ignitable

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4

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

A. Mechanical efficiency

B. Overall efficiency

C. Indicated thermal efficiency

D. Volumetric efficiency

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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 specific fuel consumption per BHP hour for diesel engine is approximately

A. 0.15 kg

B. 0.2 kg

C. 0.25 kg

D. 0.3 kg

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4

In a petrol engine, the mixture has the lowest pressure at the

A. Beginning of suction stroke

B. End of suction stroke

C. End of compression stroke

D. None of these

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4

Which of the following medium is compressed in a Diesel engine cylinder?

A. Air alone

B. Air and fuel

C. Air and lub oil

D. Fuel alone

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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

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

In petrol engines, the delay period is of the order of

A. 0.001 second

B. 0.002 second

C. 0.003 second

D. 0.004 second

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4

In a typical medium speed, 4-stroke cycle diesel engine

A. Fuel injection starts at 10° before to dead center and ends at 20° after tor dead center

B. Fuel injection starts at top dead center and ends at 20° after top dead center

C. Fuel injection starts at just before top dead center and ends just after top dead center

D. May start and end anywhere

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4

The delay period in compression ignition engines depends upon

A. Temperature and pressure in the cylinder at the time of injection

B. Nature of the fuel mixture strength

C. Relative velocity between the fuel injection and air turbulence pressure of residual gases

D. All of the above

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4

The knocking in diesel engines may be prevented by

A. Reducing the delay period

B. Raising the compression ratio

C. Increasing the inlet pressure of air

D. All of these

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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

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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 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