In SI engines knocking can be reduced by (a) Increasing the compression ratio (b) Increasing the cooling water temperature (c) Retarding the spark advance (d) Increasing the inlet air temperature

In SI engines knocking can be reduced by (a) Increasing the compression ratio (b) Increasing the cooling water temperature (c) Retarding the spark advance (d) Increasing the inlet air temperature
by

1 Answer

Answer :

Ans :c
by
selected by

Related questions

The knocking in spark ignition engines can be reduced by a. Retarding the spark. b. Increasing the engine speed. c. Both a and b d. None of these.

Description : The knocking in spark ignition engines can be reduced by a. Retarding the spark. b. Increasing the engine speed. c. Both a and b d. None of these.

Last Answer : ANSWER c. Both a and b.

The knocking in spark ignition engines can be reduced by a. Retarding the spark. b. Increasing the engine speed. c. Both a and b. d. None of these.

Description : The knocking in spark ignition engines can be reduced by a. Retarding the spark. b. Increasing the engine speed. c. Both a and b. d. None of these.

Last Answer : ANSWER c. Both a and b

Which of the following factors increases the tendency of knocking in the CI engines? (a) Increasing both the r and coolant temperatures (b) Increasing both the speed and the injection advance (c) Increasing the speed, injection advance and coolant temperature (d) Increasing the compression ratio

Description : Which of the following factors increases the tendency of knocking in the CI engines? (a) Increasing both the r and coolant temperatures (b) Increasing both the speed and the injection advance (c) Increasing the speed, injection advance and coolant temperature (d) Increasing the compression ratio

Last Answer : Ans :c

The knocking tendency in CI engines increases with (a) Increase of coolant water temperature (b) Increase of temperature of inlet air (c) Decrease of compression ratio (d) Increase of compression ratio

Description : The knocking tendency in CI engines increases with (a) Increase of coolant water temperature (b) Increase of temperature of inlet air (c) Decrease of compression ratio (d) Increase of compression ratio

Last Answer : Ans :c

In spark ignition engines, the knocking tendency can be decreased by a) decreasing compression ratio b) controlling intake throttle c) controlling ignition timing d) adding dopes like tetraethyl lead and ethylene dibromide

Description : In spark ignition engines, the knocking tendency can be decreased by a) decreasing compression ratio b) controlling intake throttle c) controlling ignition timing d) adding dopes like tetraethyl lead and ethylene dibromide

Last Answer : Answer: d Explanation: None.

Detonation can be controlled by a. varying the compression ratio b. using lean mixture c. retarding the spark timing d. reducing the rpm

Description : Detonation can be controlled by a. varying the compression ratio b. using lean mixture c. retarding the spark timing d. reducing the rpm

Last Answer : ANSWER c. retarding the spark timing

The compression ratio in a Spark Ignition (SI) engine is generally in between a. 7 to 10 b. 10 to 14 c. 14 to 18 d. 18 to 22 (Ans:a)

Description : The compression ratio in a Spark Ignition (SI) engine is generally in between a. 7 to 10 b. 10 to 14 c. 14 to 18 d. 18 to 22 (Ans:a)

Last Answer : Which of the following is not true for two stroke engine as compared to four stroke engine? a. Less cooling is required b. Greater lubrication is required c. More uniform torque on crankshaft d. Complete exhaust of products of combustion (Ans:a)

For the same capacity engines, the compression ratio of diesel engine a. is lower than the compression ratio of SI engine b. is higher than the compression ratio of SI engine c. is same as the compression ratio of SI engine d. cannot say

Description : For the same capacity engines, the compression ratio of diesel engine a. is lower than the compression ratio of SI engine b. is higher than the compression ratio of SI engine c. is same as the compression ratio of SI engine d. cannot say

Last Answer : ANSWER b. is higher than the compression ratio of SI engine

A diesel engine is usually more efficient than a spark ignition engine because a. Diesel being a heavier hydrocarbon, release more heat per kg than gasoline b. The air standard efficiency of diesel cycle is higher than the Otto cycle, at a fixed compression ratio c. The compression ratio of a diesel engine is higher than that of an Spark ignition engine d.Self ignition temperature of diesel is higher than that of gasoline.

Description : A diesel engine is usually more efficient than a spark ignition engine because a. Diesel being a heavier hydrocarbon, release more heat per kg than gasoline b. The air standard efficiency of diesel ... an Spark ignition engine d.Self ignition temperature of diesel is higher than that of gasoline.

Last Answer : ANSWER c. The compression ratio of a diesel engine is higher than that of an S.I engine

The tendency of a petrol engine to knock increases by a. supercharging b. scavenging c. increasing the engine horse power d. reducing the spark advance

Description : The tendency of a petrol engine to knock increases by a. supercharging b. scavenging c. increasing the engine horse power d. reducing the spark advance

Last Answer : ANSWER a. supercharging

The probability of knocking in diesel engines is increased by a. High self-ignition temperature. b. Low volatility. c. High viscosity. d. all of the above

Description : The probability of knocking in diesel engines is increased by a. High self-ignition temperature. b. Low volatility. c. High viscosity. d. all of the above

Last Answer : ANSWER d. all of the above

The probability of knocking in diesel engines is increased by a. High self-ignition temperature. b. Low volatility. c. High viscosity. d. All of the above

Description : The probability of knocking in diesel engines is increased by a. High self-ignition temperature. b. Low volatility. c. High viscosity. d. All of the above

Last Answer : ANSWER d. all of the above

The compression ratio cannot be increased beyond certain limit as it results in a. auto-ignition of fuel b. detonation c. engine knocking d. all the above

Description : The compression ratio cannot be increased beyond certain limit as it results in a. auto-ignition of fuel b. detonation c. engine knocking d. all the above

Last Answer : ANSWER d. all the above

Which one of the following methods can be adopted to obtain isothermal compression in an air compressor? A. Increasing the weight of the compressor B. Inter-stage heating C. Atmospheric cooling D. Providing appropriate dimensions to the cylinder

Description : Which one of the following methods can be adopted to obtain isothermal compression in an air compressor? A. Increasing the weight of the compressor B. Inter-stage heating C. Atmospheric cooling D. Providing appropriate dimensions to the cylinder

Last Answer : ANSWER : A

With increase in __________ Knocking tendency in a spark ignition petrol engine decreases. (A) Supercharging (B) Wall temperature (C) Compression ratio (D) Engine speed

Description : With increase in __________ Knocking tendency in a spark ignition petrol engine decreases. (A) Supercharging (B) Wall temperature (C) Compression ratio (D) Engine speed

Last Answer : Option D

In _____________ sensor, output voltage changes in proportion to air-fuel ratio. a) engine temperature b) exhaust gas c) air flow d) air inlet temperature

Description : In _____________ sensor, output voltage changes in proportion to air-fuel ratio. a) engine temperature b) exhaust gas c) air flow d) air inlet temperature

Last Answer : Answer: b Explanation: Only in exhaust gas sensor, output voltage changes in proportion to air-fuel ratio.

_____________ senor senses the amount of oxygen in the engine exhaust and calculates air-fuel ratio. a) Engine temperature b) Exhaust gas c) Air flow d) Air inlet temperature

Description : _____________ senor senses the amount of oxygen in the engine exhaust and calculates air-fuel ratio. a) Engine temperature b) Exhaust gas c) Air flow d) Air inlet temperature

Last Answer : Answer: b Explanation: Exhaust gas senor senses the amount of oxygen in the engine exhaust and calculates airfuel ratio while engine temperature sensor senses the temperature of the engine coolant, and from this data the computer adjusts the mixture strength to rich side for cold starting.

In a morse test for a 2 cylinder, 2 S SI engine, the brake power was 9 kW. Whereas the brake power of individual cylinders with spark cut off were 4.25 kW and 3.75 kW. The mecheffic of the engine is (a) 90% (b) 80% (c) 45.5% (d) 52.5%

Description : In a morse test for a 2 cylinder, 2 S SI engine, the brake power was 9 kW. Whereas the brake power of individual cylinders with spark cut off were 4.25 kW and 3.75 kW. The mecheffic of the engine is (a) 90% (b) 80% (c) 45.5% (d) 52.5%

Last Answer : Ans :a

Scavenging air in diesel engine means a. air used for combustion under pressure b. forced air for cooling the cylinder c. burnt air containing products of combustion d. air used for forcing burnt gases out of the engines cylinder during the exhaust stroke

Description : Scavenging air in diesel engine means a. air used for combustion under pressure b. forced air for cooling the cylinder c. burnt air containing products of combustion d. air used for forcing burnt gases out of the engines cylinder during the exhaust stroke

Last Answer : ANSWER d. air used for forcing burnt gases out of the engines cylinder during the exhaust stroke

What is sensible cooling of air? A. the cooling in which sensible heat of air is removed in order to reduce temperature B. the cooling in which temperature of air is reduced without changing in its moisture content C. both a. and b. D. none of the above

Description : What is sensible cooling of air? A. the cooling in which sensible heat of air is removed in order to reduce temperature B. the cooling in which temperature of air is reduced without changing in its moisture content C. both a. and b. D. none of the above

Last Answer : ANSWER : C

Explain the effect of spark advance and retardation on knocking.

Description : Explain the effect of spark advance and retardation on knocking.

Last Answer : Advanced spark: - Quantity of fuel burnt per cycle before and after TDC position depends on spark timing. The temperature of charge increases by increasing the spark advance and it increases with ... indicates smooth engine running when the maximum pressure is built up when piston reaches TDC.  

Which of the following engine can work on very lean mixture a. Spark ignition engine b. compression ignition engine c. two stroke engine d. Four stroke engine

Description : Which of the following engine can work on very lean mixture a. Spark ignition engine b. compression ignition engine c. two stroke engine d. Four stroke engine

Last Answer : ANSWER b. compression ignition engine

Morse test is conducted on the engine to calculate the mechanical efficiency of A. single cylinder CI engine B. single cylinder SI engine C. only on two stroke engines D. multi cylinder engine

Description : Morse test is conducted on the engine to calculate the mechanical efficiency of A. single cylinder CI engine B. single cylinder SI engine C. only on two stroke engines D. multi cylinder engine

Last Answer : ANSWER : D

For same power output and same r, as compared to 2- stroke engines, four stroke SI engines have (a) Higher fuel consumption (b) Lower thermal efficiency (c) Highest exhaust temperatures (d) Higher thermal efficiency

Description : For same power output and same r, as compared to 2- stroke engines, four stroke SI engines have (a) Higher fuel consumption (b) Lower thermal efficiency (c) Highest exhaust temperatures (d) Higher thermal efficiency

Last Answer : Ans :d

The critical spark energy required to ignite a given mixture A. decreases with decreasing sparking voltage B. increases with decreasing sparking voltage C. increases with increasing sparking voltage D. decreases with increasing sparking voltage

Description : The critical spark energy required to ignite a given mixture A. decreases with decreasing sparking voltage B. increases with decreasing sparking voltage C. increases with increasing sparking voltage D. decreases with increasing sparking voltage

Last Answer : ANSWER : D

Anti-knock for compression ignition engines is a) napthene b) tetra ethyl lead c) amyl nitrate d) hexadecane

Description : Anti-knock for compression ignition engines is a) napthene b) tetra ethyl lead c) amyl nitrate d) hexadecane

Last Answer : Answer: c Explanation: Amyl nitrate is the anti-knock for compression ignition engines.

In compression ignition engines, swirl denotes a. Haphazard motion of the gases in the cylinder b. Rotary motion of the gases in the cylinder. c. Radial motion of the gases in the cylinder. d. None of the above

Description : In compression ignition engines, swirl denotes a. Haphazard motion of the gases in the cylinder b. Rotary motion of the gases in the cylinder. c. Radial motion of the gases in the cylinder. d. None of the above

Last Answer : ANSWER a. Haphazard motion of the gases in the chamber

Most high-speed compression engines operate on a. diesel cycle b. Otto cycle c. dual cycle d. Carnot cycle

Description : Most high-speed compression engines operate on a. diesel cycle b. Otto cycle c. dual cycle d. Carnot cycle

Last Answer : ANSWER c. dual cycle

The _____________ sensor, checks the temperature of the ambient air entering the engine for fine tuning the mixture strength. a) engine temperature b) exhaust gas c) air flow d) air inlet temperature

Description : The _____________ sensor, checks the temperature of the ambient air entering the engine for fine tuning the mixture strength. a) engine temperature b) exhaust gas c) air flow d) air inlet temperature

Last Answer : Answer: d Explanation: The air inlet temperature sensor, checks the temperature of the ambient air entering the engine for fine tuning the mixture strength whereas the engine temperature sensor senses the ... gas senor senses the amount of oxygen in the engine exhaust and calculates air-fuel ratio.

The _____________ sensor, monitors mass or volume of air flowing into the intake manifold for adjusting the quantity of fuel. a) engine temperature b) exhaust gas c) air flow d) air inlet temperature

Description : The _____________ sensor, monitors mass or volume of air flowing into the intake manifold for adjusting the quantity of fuel. a) engine temperature b) exhaust gas c) air flow d) air inlet temperature

Last Answer : Answer: c Explanation: The air flow sensor, monitors mass or volume of air flowing into the intake manifold for adjusting the quantity of fuel while exhaust gas senor senses the amount of oxygen in the engine exhaust and calculates air-fuel ratio.

The _____________ sensor senses the temperature of the engine coolant, and from this data the computer adjusts the mixture strength to rich side for cold starting. a) engine temperature b) exhaust gas c) air flow d) air inlet temperature

Description : The _____________ sensor senses the temperature of the engine coolant, and from this data the computer adjusts the mixture strength to rich side for cold starting. a) engine temperature b) exhaust gas c) air flow d) air inlet temperature

Last Answer : Answer: a Explanation: The engine temperature sensor senses the temperature of the engine coolant, and from this data the computer adjusts the mixture strength to rich side for cold starting while the ... gas senor senses the amount of oxygen in the engine exhaust and calculates air-fuel ratio.

The tendency of knocking in CI engine reduces by (a) High self ignition temperature of fuel (b) Decrease in jacket water temperature (c) Injection of fuel just before TDC (d) Decrease in injection pressure

Description : The tendency of knocking in CI engine reduces by (a) High self ignition temperature of fuel (b) Decrease in jacket water temperature (c) Injection of fuel just before TDC (d) Decrease in injection pressure

Last Answer : Ans :c

The air fuel ratio in petrol engines is controlled by a. valve opening / closing b. governing c. carburetion d. scavenging

Description : The air fuel ratio in petrol engines is controlled by a. valve opening / closing b. governing c. carburetion d. scavenging

Last Answer : ANSWER c. carburetion

In a SI engine, which one of the following is the correct order of the fuels with increasing detonation tendency? (a) Paraffins, olefins, naphthenes, aromatics (b) Aromatics, naphthenes, paraffins, olefins (c) Naphthenes, olefins, aromatics, paraffins (d) Aromatics, naphthenes, olefins, paraffins

Description : In a SI engine, which one of the following is the correct order of the fuels with increasing detonation tendency? (a) Paraffins, olefins, naphthenes, aromatics (b) Aromatics, naphthenes, paraffins, olefins (c) Naphthenes, olefins, aromatics, paraffins (d) Aromatics, naphthenes, olefins, paraffins

Last Answer : Ans :d

For spark ignition engine, the equivalence ratio of mixture entering the combustion chamber has values (A) for idling and for peak power conditions (B) for both idling and peak power conditions (C) for idling and for peak power conditions (D) for both idling and peak power conditions

Description : For spark ignition engine, the equivalence ratio of mixture entering the combustion chamber has values (A) for idling and for peak power conditions (B) for both idling and peak power conditions (C) for idling and for peak power conditions (D) for both idling and peak power conditions

Last Answer : ANSWER (B) for both idling and peak power conditions

In multi stage compressor, the isothermal compression is achieved by A. Employing intercooler B. By constantly cooling the cylinder C. By running compressor at very slow speed D. By insulating the cylinder

Description : In multi stage compressor, the isothermal compression is achieved by A. Employing intercooler B. By constantly cooling the cylinder C. By running compressor at very slow speed D. By insulating the cylinder

Last Answer : ANSWER : C

Mixing of air and fuel in the diesel engine occurs in a. injection pump b. carburetor c. engine cylinder d. inlet manifold

Description : Mixing of air and fuel in the diesel engine occurs in a. injection pump b. carburetor c. engine cylinder d. inlet manifold

Last Answer : ANSWER c. engine cylinder

In diesel engine, the fuel is ignited by a. spark b. injected fuel c. heat resulting from compressing air that is supplied for combustion d. ignitor

Description : In diesel engine, the fuel is ignited by a. spark b. injected fuel c. heat resulting from compressing air that is supplied for combustion d. ignitor

Last Answer : ANSWER c. heat resulting from compressing air that is supplied for combustion

An ideal air standard Otto cycle has a compression ratio of 8.5. If the ratio of the specific heats is 1.4, then what is thermal efficiency (in percentage) of the Otto cycle? a. 57.5% b. 45.7% c. 52.5% d. 95%

Description : An ideal air standard Otto cycle has a compression ratio of 8.5. If the ratio of the specific heats is 1.4, then what is thermal efficiency (in percentage) of the Otto cycle? a. 57.5% b. 45.7% c. 52.5% d. 95%

Last Answer : ANSWER a. 57.5%

Compare SI and CI engine on the basis of air-fuel ratio, power output, emission and knocking.

Description : Compare SI and CI engine on the basis of air-fuel ratio, power output, emission and knocking.

Last Answer : Parameter SI engine CI engine Air-fuel ratio air-fuel ratio is 14.7:1 air-fuel ratio is 20:1 to 70:1  Power output  Power output is Less than CI engine due ... Knocking take place at the end of combustion. Knocking take place at beginning or start of the combustion. 

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

Description : 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

Last Answer : Answer: a Explanation: None.

If petrol is used in a diesel engine a. higher knocking will occur b. efficiency will be low c. low power will be obtained d. black smoke will be produced

Description : If petrol is used in a diesel engine a. higher knocking will occur b. efficiency will be low c. low power will be obtained d. black smoke will be produced

Last Answer : ANSWER a. higher knocking will occur

Explain the effect of the following engine variables on ignition lag and flame propagation: (i) cylinder size (ii) cylinder wall temperature (iii) compression ratio and (iv) inlet air temperature

Description : Explain the effect of the following engine variables on ignition lag and flame propagation: (i) cylinder size (ii) cylinder wall temperature (iii) compression ratio and (iv) inlet air temperature

Last Answer : (i) Cylinder size - Engine of similar design generally run at the same speed. This is achieved by smaller engine having larger RPM and larger engines having smaller RPM. Due to the same ... all reduces the ignition lag. Pre-increase in the intake temperature and pressure increases the flame speed.

How the efficiency of the SI engine is affected by the specific heat ratio (γ) of the working fluid? a. the efficiency of the engine increases with increase in specific heat ratio (γ) of the working fluid b. the efficiency of the engine decreases with increase in specific heat ratio (γ) of the working fluid c. the efficiency of the engine does not affected by change in specific heat ratio (γ) of the working fluid d. none of the above

Description : How the efficiency of the SI engine is affected by the specific heat ratio (γ) of the working fluid? a. the efficiency of the engine increases with increase in specific heat ratio (γ) of the working ... not affected by change in specific heat ratio (γ) of the working fluid d. none of the above

Last Answer : ANSWER a. the efficiency of the engine increases with increase in specific heat ratio (γ) of the working fluid

In four stroke engine which of the following is also known as power stroke a. Suction stroke b. Compression stroke c. Expansion stroke d. Exhaust stroke (Ans:c) Measurements of fuel and air consumption, brake power and incylinder pressure. Tutorials on engine performance parameters. Heat balance sheet. Engine performance curves. 1. The increase in intake air temperature into IC engine,___________its efficiency A. increase B. decrease C. does not alter D. unpredictable on

Description : In four stroke engine which of the following is also known as power stroke a. Suction stroke b. Compression stroke c. Expansion stroke d. Exhaust stroke (Ans:c) Measurements of fuel and air ... into IC engine,___________its efficiency A. increase B. decrease C. does not alter D. unpredictable on

Last Answer : ANSWER : B

Which one of the following statements are correct for reciprocating air compressor? A. Its volumetric efficiency increases with increasing clearance ratio B. Its volumetric efficiency increases with pressure ratio C. Its volumetric efficiency does not vary with change in clearance ratio and pressure ratio D. Its volumetric efficiency decreases with increasing clearance ratio and pressure ratio

Description : Which one of the following statements are correct for reciprocating air compressor? A. Its volumetric efficiency increases with increasing clearance ratio B. Its volumetric efficiency increases ... ratio D. Its volumetric efficiency decreases with increasing clearance ratio and pressure ratio

Last Answer : ANSWER : D

Dew point can be best defined as the: a. Absolute temperature at which air, upon heating, will evaporate moisture b. . Percentage of moisture that air can hold at a given temperature and pressure c. . Temperature that air will begin to evaporate moisture d. . Temperature at which air, upon cooling, becomes saturated, causing moisture to condense should the temperature drop further e. . Atmospheric pressure at which air will condense moisture

Description : Dew point can be best defined as the: a. Absolute temperature at which air, upon heating, will evaporate moisture b. . Percentage of moisture that air can hold at a given temperature ... to condense should the temperature drop further e. . Atmospheric pressure at which air will condense moisture

Last Answer : Answer: D

In sensible heating or cooling, A. work done remains constant B. dry bulb temperature or air remains constant C. both of the mentioned D. none of the mentioned

Description : In sensible heating or cooling, A. work done remains constant B. dry bulb temperature or air remains constant C. both of the mentioned D. none of the mentioned

Last Answer : ANSWER : A

Alcohols alone cannot be used in CI engines as a) their self ignition temperature is high b) latent heat of vaporization is high c) all of the mentioned d) none of the mentioned

Description : Alcohols alone cannot be used in CI engines as a) their self ignition temperature is high b) latent heat of vaporization is high c) all of the mentioned d) none of the mentioned

Last Answer : Answer: c Explanation: None.

As a result of detonation in Internal combustion engines the following parameter attains very high value. a. peak pressure b. rate of rise of pressure c. rate of rise of temperature. d. peak temperature.

Description : As a result of detonation in Internal combustion engines the following parameter attains very high value. a. peak pressure b. rate of rise of pressure c. rate of rise of temperature. d. peak temperature.

Last Answer : ANSWER b. rate of rise of pressure