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4

Fuel consumption of diesel engines is not guaranteed at one quarter load because at such low loads

A. The friction is high

B. The friction is unpredictable

C. The small difference in cooling water temperature or in internal friction has a disproportionate effect

D. The engine is rarely operated

Correct Answer :

C. The small difference in cooling water temperature or in internal friction has a disproportionate effect


Related Questions

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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 diesel engine, the compression ratio in comparison to expansion ratio is

A. Same

B. Less

C. More

D. Variable

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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 magneto in an automobile is basically

A. Transformer

B. D.C. generator

C. Capacitor

D. Magnetic circuit

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4

Which is more viscous lube oil?

A. SEA 30

B. SAE 50

C. SAE 70

D. SAE 80

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4

In a cycle, the spark lasts roughly for

A. 1 sec

B. 0.1 sec

C. 0.01 sec

D. 0.001 sec

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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 cetane number of diesel oil, generally available, is

A. 20 to 25

B. 25 to 30

C. 30 to 40

D. 40 to 55

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4

Antiknock for compression ignition engines is

A. Napthene

B. Tetra ethyl lead

C. Amyl nitrate

D. Hexadecane

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4

A heat engine utilises the

A. Calorific value of oil

B. Low heat value of

C. High heat value of oil

D. Mean heat value of oil

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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

Pre-ignition is caused by the spontaneous combustion of the mixture before the end of the compression stroke, and is due to

A. Cylinder walls being too hot

B. Overheated spark plug points

C. Red hot carbon deposits on cylinder walls

D. Any one of these

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4

If the compression ratio of an engine working on Otto cycle is increased from 5 to 7, the percentage increase in efficiency will be

A. 2 %

B. 4 %

C. 8 %

D. 14 %

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4

In order to prevent knocking in spark ignition engines, the charge away from the spark plug should have

A. Low density

B. Low temperature

C. Long ignition delay

D. All of these

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4

The thermal efficiency of petrol and gas engines is about

A. 15 %

B. 30 %

C. 50 %

D. 70 %

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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

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

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 cetane (C16H34) which is a straight chain paraffin, is assigned a cetane number of

A. 0

B. 50

C. 100

D. 120

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4

The maximum temperature in the I.C. engine cylinder is of the order of

A. 500-1000°C

B. 1000-1500°C

C. 1500-2000°C

D. 2000-2500°C

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4

In a four stroke cycle petrol engine, the pressure inside the engine cylinder during the suction stroke is __________ the atmospheric pressure.

A. Equal to

B. Below

C. Above

D. None of these

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4

Diesel as compared to petrol is

A. Highly ignitable

B. More difficult to ignite

C. Less difficult to ignite

D. None of these

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4

The knock in diesel engine occurs due to

A. Instantaneous and rapid burning of the first part of the charge

B. Instantaneous auto ignition of last part of charge

C. Delayed burning of the first part of the charge

D. Reduction of delay period

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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

If one cylinder of a diesel engine receives more fuel than the others, then for that cylinder the

A. Exhaust will be smoky

B. Piston rings would stick into piston grooves

C. Engine starts overheating

D. Scavenging occurs

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4

The reflectivity depends upon

A. Geometry of the reflector

B. Energy of neutrons

C. Properties of the reflector

D. All of these

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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

In an internal combustion engine, the process of removing the burnt gases from the combustion chamber of the engine cylinder is known as

A. Scavenging

B. Detonation

C. Supercharging

D. Polymerisation

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4

Scavenging is usually done to increase

A. Thermal efficiency

B. Speed

C. Power output

D. Fuel consumption

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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