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4

The octane number of petrol, generally available, is

A. 20 to 40

B. 40 to 60

C. 60 to 80

D. 80 to 100

Correct Answer :

D. 80 to 100


Related Questions

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4

The brake power of a diesel engine, keeping other parameters constant, can be increased by

A. Decreasing the density of intake air

B. Increasing the temperature of intake air

C. Increasing the pressure of intake air

D. Decreasing the pressure of intake air

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4

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

A. More efficient

B. Less efficient

C. Equally efficient

D. Other factors will decide it

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4

Which of the following statement is wrong?

A. In compression ignition engines, detonation occurs near the beginning of combustion.

B. Since the fuel, in compression ignition engines, is injected at the end of compression stroke, therefore, there will be no pre-ignition.

C. To eliminate knock in compression ignition engines, we want to achieve auto-ignition not early and desire a long delay period.

D. In compression ignition engines, because of heterogeneous mixture, the rate of pressure rise is comparatively lower.

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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

The brake power is the power available

A. In the engine cylinder

B. At the crank shaft

C. At the crank pin

D. None of these

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4

In a four stroke cycle petrol engine, the inlet valve

A. Opens at top dead centre and closes at bottom dead centre

B. Opens at 20° before top dead centre and closes at 40° after bottom dead centre

C. Opens at 20° after top dead centre and closes at 20° before bottom dead centre

D. May open or close anywhere

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4

The knocking tendency in compression ignition engines for a given fuel will be

A. Enhanced by decreasing compression ratio

B. Enhanced by increasing compression ratio

C. Dependent on other factors

D. None of the above

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4

Morse test is used to determine the I.P. of a

A. Single cylinder petrol engine

B. Four stroke engine

C. Single cylinder diesel engine

D. Multi cylinder engine

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4

Theoretically, a four stroke cycle engine should develop _________ power as that of a two stroke cycle engine.

A. Half

B. Same

C. Double

D. Four times

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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

A fuel of an octane number rating of 75 matches in knocking intensity as a mixture of

A. 75% iso-octane and 25% normal heptane

B. 75% normal heptane and 25% iso-octane

C. 75% petrol and 25% diesel

D. 75% diesel and 25% petrol

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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

Crankcase explosion in I.C. engines usually occurs as

A. First a mild explosion followed by a bi explosion

B. First a big explosion followed by a mil explosion

C. Both mild and big explosions occurs simultaneously

D. Never occurs

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4

A higher compression ratio causes

A. Pre-ignition

B. Increase in detonation

C. Acceleration in the rate of combustion

D. Any one of these

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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 mean effective pressure obtained from engine indicator indicates the

A. Maximum pressure developed

B. Minimum pressure

C. Instantaneous pressure at any instant

D. Average pressure

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4

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

A. Uniform throughout the mixture

B. Chemically correct mixture

C. About 35% of rich mixture

D. About 10% of rich mixture

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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

Pick up the wrong statement about supercharging

A. Supercharging reduces knocking in diesel engines

B. There can be limited supercharging in petrol engines because of detonation

C. Supercharging at high altitudes is essential

D. Supercharging results in fuel economy

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4

An engine indicator is used to determine the following

A. Speed

B. Temperature

C. Volume of cylinder

D. m.e.p. and I.H.P.

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4

The thermodynamic cycle on which the petrol engine works, is

A. Otto cycle

B. Joule cycle

C. Rankine cycle

D. Stirling cycle

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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

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

In a petrol engine, the fuel supplied to the engine cylinder is mixed with required quantity of air and the mixture is ignited with a

A. Fuel pump

B. Fuel injector

C. Spark plug

D. None of these

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4

The fuel air ratio in a petrol engine fitted with suction carburettor, operating with dirty air filter as compared to clean filter will be

A. Higher

B. Lower

C. Remain unaffected

D. None of the above

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4

The function of a distributor in a coil ignition system of I.C. engines is

A. To distribute spark

B. To distribute power

C. To distribute current

D. To time the spark

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4

A carburettor is used to supply

A. Petrol, air and lubricating oil

B. Air and diesel

C. Petrol and lubricating oil

D. Petrol and air

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4

The purpose of testing an internal combustion engine is

A. To determine the information, which cannot be obtained by calculations

B. To conform the data used in design, the validity of which may be doubtful

C. To satisfy the customer regarding the performance of the engine

D. All of the above

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4

The term scavenging is generally associated with

A. 2-stroke cycle engines

B. 4-stroke cycle engines

C. Aeroplane engines

D. High efficiency engines

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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