Description : Enlist drawbacks of carbureted (SI) Engine on the basis of emission fuel Consumption, Air fuel ratio and fuel distribution.
Last Answer : Drawbacks of carbureted (SI) Engine. Parameter Drawbacks Emission Does not meet emission Norms Fuel consumption Due to absence of throttling specific fuel consumption is ... distribution of charge. Fuel distribution for each cylinder is not equal for multi cylinder engine.
Description : Discuss the drawbacks of carbureted SI engine on the base of, Air-fuel ratio, fuel consumption, power output, emission.
Last Answer : 1) Air-fuel ratio: - As in SI engine Air-fuel ratio varies from 8:1 to 18.5:1 i.e. from 8 kg of air/kg of fuel to 18.5 kg of air/kg of fuel. Richer or leaner air-fuel ratio limit causes the engine to ... 8 kg of air/kg of fuel to 18.5 kg of air/kg of fuel. So emission is more in SI engine.
Description : List two drawbacks of carbureted SI engine during fuel distribution and drivability.
Last Answer : Fuel distribution : Drawbacks 1. Mal-distribution of charge. 2. Inaccurate metering of charge. 3. Fuel atomization depends upon velocity of air in the venture. Drivability: Drawbacks 1 ... temperature compensation. 4) No compensation of Exhaust gas recirculation. 5) Backfiring may take place.
Description : State four drawbacks of carbureted SI engine
Last Answer : Drawbacks of carbureted SI engine: 1) No altitude compensation. 2) Mal-distribution of charge. 3) Variation in air: fuel ratio. 4) Inaccurate metering of charge. 5) Does not meet emission ... in poor efficiency. 10) Backfiring may take place. 11) Carburetor Icing may take place.
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.
Description : Compare carbureted engine fuel supply system with MPFI system.
Last Answer : Sr.No. Carbureted fuel supply system MPFI fuel supply system 1 Mal-distribution of charge. Uniform distribution of charge. 2 Due to resistance in intake manifold volumetric ... is take place inside the manifold. fuel being injected into or close to the cylinder.
Description : Explain the various stages of combustion in SI engines.
Last Answer : The stages of combustion in SI engines Stage I:-Ignition Lag or Preparation Phase. Stage II: - Propagation of flame. Stage III: - After burning.
Description : Compare performance characteristics of SI and CI engines.
Last Answer : Variable/Parameter SI Engine CI Engine Power output per unit weight 2.7 Kg/Kw 6.5 Kg/Kw Power output per unit displacement 30 Kw/liter 15 Kw/liter Acceleration Not ... load, idling. Fuel safety More volatile so less safer Less volatile so more safer
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
Description : Compare carbureted engine with MPFI engine
Last Answer : Sr. Carbureted fuel system Electronic fuel injection system 1 Mal-distribution of charge. Uniform distribution of charge. 2 Due to resistance in intake manifold volumetric ... is take place inside the manifold. Fuel being injected into or close to the cylinder.
Description : State four properties of SI engine fuel.
Last Answer : 1. It should mix readily with air and provide uniform manifold distribution. That is, it should easily vaporize. 2. It must be knock resistant. 3. It should not pre-ignite easily. 4. It should ... not form gum and varnish. OR 1. Volatility2. Knock Resistivity 3. Sulphur Content 4. Gum Content
Description : Explain any two engine modifications and two fuel modifications to control emission from gasoline engine.
Last Answer : Methods used for improving the exhaust emission under the engine design modification are 1. Use of leaner air-fuel ratios: The carburetor may be modified to provide relatively lean air ... Fuel Volatility: Fuel volatility is compromise of high volatility and low volatility to control the pollution
Description : Describe air fuel- ratio requirements for diesel engines at no load to full load.
Last Answer : Irrespective of load at any given speed, an approximately constant supply of air enters the cylinder. With change in load, the quantity of fuel injected is changed varying the air fuel ratio. The ... engine always designed to operate with an excess air of 15 to 40% depending upon the application
Description : Differentiate air fuel ratio between carburetted engine and electronic fuel injection engines control system.
Last Answer : Sr. No. Carburetted engine Electronic Fuel Injection (EFI) engine 1 Fuel atomization depends upon velocity of air in the venturi. Atomization of fuel is independent of cranking ... occurs in carbureted engine. Equal quantity of fuel is supplied to port for each cylinder
Description : Give advantages and disadvantages of LPG as a fuel for automobile engines.
Last Answer : Advantages of LPG 1. It is cheaper than petrol 2. It is highly detonation resistant and does not pre-ignite easily. 3. It gives better manifold distribution and mixes easily with air. 4. Residue ... 13. It is safe only if proper periodic maintenance of the gas system is done by trained person.
Description : LPG is used as an alternative fuel for SI engine. Justify your answer
Last Answer : LPG is used as an alternative fuel for SI engine because of following advantages. 1. The exceptional advantages of LPG as an alternative engine fuel have been mainly from the simplicity of its ... plug is increased. 9. Fuel supply system can be easily modified by introducing a conversion kit.
Description : Describe four properties of gasoline as a fuel for SI engine
Last Answer : Volatility: volatility depend upon fractinal composition of fuel. Method of measuring volatility has been standardized by ASTM ( American society of Testing Materials) and the graohical representation ... gasoline to improve the gasoline stability during storage by inhibiting the formation of gums.
Description : Discuss causes and remedies for following faults in CI engine: (i) Engine does not start or stalls just after starting (ii) Excessive fuel consumption.
Last Answer : I) Engine does not start or stalls just after starting
Description : Explain working of Variable Valve Timing and Electronic lift control (VTEC) system. Enlist its advantage and Drawbacks
Last Answer : Answer: Working of Variable Valve Timing and Electronic lift control (VTEC) system:- VTEC (which stands for Variable Valve Timing and Lift Electronic Control) is an electronic and mechanical system ... 2) Maintenance cost is high 3) Very complex structure required complicated control system.
Description : List four drawbacks of carburetted S.I. engine.
Last Answer : Drawbacks of carburetted SI engine: 1) No altitude compensation. 2) Mal-distribution of charge. 3) Variation in air: fuel ratio. 4) Inaccurate metering of charge. 5) Does not meet emission ... parts results in poor efficiency. 10) Backfiring may take place. 11) Carburetor Icing may take place
Description : Compare detonation and diesel knock on the basis of (i) Fuel Ignition Temperature (ii) Compression Ratio (iii) Speed (iv) inlet temperature (v) inlet pressure (vi) cylinder wall temperature (vii) cylinder size
Last Answer : Comparison between detonation and diesel knock: Parameter To avoid Detonation in SI Engine To avoid Diesel knock i) Fuel Ignition Temperature High Low ii) Compression Ratio ... Cylinder wall temperature Low High viii) Cylinder size Small Large
Description : State the pollutants from gasoline engines. And explain why it is formed?
Last Answer : Pollutants from gasoline engine 1. Carbon monoxide (CO) 2. Hydrocarbons (HC) 3. Oxides of nitrogen (NO) 4. Sulpher Cause of pollutants formed 1. Pollutants are produced by the incomplete ... in the combustion chamber. 2. Due to no maintenance. 3. Crankcase blowby 4. Evaporative losses.
Description : State the different types of SI engine combustion chambers. Draw a neat sketch of any one.
Last Answer : 1) T Head Type Combustion chambers 2) L Head Type Combustion chambers 3) F- Head combustion chamber 4) Over head valve or I head combustion chamber 5) Hemispherical combustion chamber 6) Bathtub ... - Head combustion chamber 4) Over head valve or I head combustion chamber
Description : Explain Evaporative emission control system.
Last Answer : EVAP system Operation: When the engine is running, stored fuel vapours in fuel tank are purged from the canister whenever the throttle has opened past the purge port and coolant temperature is above 54 °C. ... The EVAP system is designed to limit maximum vacuum and pressure in the fuel tank.
Description : List eight ways of reducing pollution. Explain PCV and evaporative emission system with suitable sketch.
Last Answer : Eight ways of reducing pollution:- 1) Optimize Ignition Advance 2) Use unleaded gasoline & Low sulphur diesel 3) Use leaner air fuel ratio 4) Use exhaust gas treatment devices ex Catalytic ... check valve. The EVAP system is designed to limit maximum vacuum and pressure in the fuel tank.
Description : How gasoline engine emission is controlled by engine design modification and treatment of exhaust gas?
Last Answer : Methods used for controlling of gasoline engine emission by engine design modification are:- 1. Use of leaner air-fuel ratios: The carburetor may be modified to provide relatively lean air fuel mixtures ... ) to open and close the EGR valve. Thus it controls the amount of exhaust gas recalculated.
Description : Explain the effect of positive crankcase ventilation (PCV) system on engine emission.
Last Answer : PCV system: The purpose of PCV system is to remove the harmful gases from the crankcase before damage occurs and combine them with the engine's normal incoming air: fuel mixture. ... is optimized, while engine performance and drivability remains unaffected positive crankcase ventilation
Description : Describe with neat sketch operation of PCV valve under different engine operating condition to control/ emission
Last Answer : PCV Valve: It consists of a spring loaded tapered valve for flow control. The crankcase pressure and manifold vacuum act together to close the valve whereas the spring pressure tends to keep it open.( ... at idle and low speed (c)High speed/Load operation (d)Preventing backfire during cranking
Description : List the various fuels used in I.C. engines. Write the properties of Biodiesel Fuels used in I. C. engine.
Last Answer : 1 Petrol 2. Diesel 3. LPG 4. CNG 5.Hydrogen 6.Alcohol 7.Bio diesel Properties biodiesel i) It is a renewable substitute fuel for petroleum diesel. ii) It has lower exhaust ... diesel vi) It is an environmentally friendly fuel that an be used in any diesel engine without modification.
Description : What is mean by ignition limit? Give ignition limit for SI engine.
Last Answer : Ignition Limit corresponds approximately to that mixture ratio, at lean & rich ends of the scale, where the heat released by spark is no longer sufficient to initiate combustion in the neighboring un-burnt mixture. ... 7:1 to 30:1 Actual Ignition limits for hydrocarbon fuels are 9:1 to 21:1
Description : Draw P-Q diagram for stages of combustion in SI engine and write stages of combustion with its explanation.
Last Answer : The stages of combustion in S.I. engine: Stage I: Ignition Lag or Preparation Phase: It is a chemical process which depends on-nature of fuel, temperature & pressure, ... The rate of combustion reduces due to surface of the flame front becoming smaller and reduction in turbulence.
Description : What is meant by surface ignition in SI engine?
Last Answer : Surface ignition: Surface ignition is the ignition of the fuel-air mixture by a hot spot on the combustion chamber walls such as on overheated valve or spark plug or glowing combustion Chamber ... and start propagates across the chamber in an analogous manner to what occurs in normal knock.
Description : Draw neat sketch to show TBI system of SI engine and name its parts.
Last Answer : Draw neat sketch to show TBI system of SI engine and name its parts.
Description : Enlist the measures of control detonation in SI engine.
Last Answer : Detonation can be control by any or all of the following techniques: 1) Use of a fuel with high octane rating. 2) Enriching the air-fuel ratio. 3) Reducing peak cylinder pressure. 4) decreasing ... . 8) Retarding spark. 9) Water injection 10) Use of high octane fuel can eliminate detonation.
Description : Draw P-ⱷ diagram showing stages of combustion in SI engine.
Last Answer : Stages of combustion in SI engines Stage I: Ignition Lag or Preparation Phase: The time elapsed between the fuel injection into the combustion chamber and starting of combustion. It is the growth ... reduces due to surface of the flame front becoming smaller and reduction in turbulence.
Description : State four methods to improve fuel economy of a vehicle.
Last Answer : Answer: Methods of improving fuel economy. 1) Use of multi-functional fuel additives will provide 3 to 4% fuel economy. 2) Good driving habits. 3) Properly maintained fuel supply ... computer controlled ignition system. 6) Use of higher voltage automotive electrical system (42 volts system).
Description : Draw a layout of fuel injection system in CRDI diesel engine. State its fundamental requirement.
Last Answer : Fundamental requirement:-The line diagram of CRDI shows that the system is controlled by ECU. The sensors in the system are used to feed the input in the ECU.ECU will provide the signal ... fuel injector, common rail, High pressure fuel pump, ECM/ECU, Pressure sensor, Rail pressure limiter.
Description : State input and output control functions of ECM. Describe the idle speed control with sketch.
Last Answer : Inputs and outputs of Electronic Control Module The inputs of ECM 1. The Ignition (Engine Speed Sensor). 2. Temperature Sensor (Coolant Temperature). 3. Throttle Potentiometer (Intake ... through. The Idle speed control valve stepper motor allows 125 possible valve opening positions.
Description : Compare the following fuels on the basis of calorific value and knocking. LPG, CNG and bio-diesel
Last Answer : Parameter LPG CNG Bio-diesel Calorific value 46.4MJ/Kg LPG has consistent & higher calorific value. 52.34 MJ/Kg Which is higher than LPG. 37.27 MJ/Kg this ... 65 which is higher than petro-diesel. So intensity of knocking is less in biodiesel compared to petro diesel.
Description : Explain the methods of fuel injection used EFI system.
Last Answer : Methods of fuel injection: 1. Sequential fuel injection. (SFI) 2. Grouped fuel injection. 3. Simultaneous fuel injection. 4. Continuous injection. 1. Simultaneous Injection: Injection of fuel ... of the fuel injection is determined by ECU depending upon load and speed.
Description : Compare throttle body injection with port fuel injection systems.
Last Answer : Sr. No. TBI system PFI System 1 Fuel is injected into the center of the throttle body. Fuel is injected into the port 2 TBI uses bottom feed ... the throttle body. Hither power output due to low resistance at intake manifold and higher volumetric efficiency.
Description : CNG is used as alternative fuel, justify with four merits and four demerits.
Last Answer : 1. CNG reduces the harmful emission 2. Operating cost of the vehicle running on CNG is lower. 3. Reduced vehicle maintenance. 4. Fuel theft is not possible. Since NG cannot be siphoned ... 5. Inconsistent fuel properties. So above merits and demerits suggest that CNG is used as alternative fuel.
Description : Describe the working of high pressure fuel pump.
Last Answer : Working: Downward motion of plunger: The safety valve at the inlet opens if the pre-supply pressure of fuel exceeds 1.5 bars and fuel comes and fills the chamber till the plunger moves up to BDC. ... . A constant pressure of about 1400 to 1600 bar is maintained in the common rail.
Description : List three methods of fuel injection. Describe sequential method with suitable sketch.
Last Answer : Methods of petrol injection 1. Sequential fuel injection. (SFI) 2. Grouped fuel injection. 3. Simultaneous fuel injection 4. Continuous injection. Sequential Injection: Each injector ... to crank/ camshaft position and pulse width, can be optimized for each individual cylinder.
Description : List any four parameters of improving fuel economy.
Last Answer : 1. Use of multi-functional fuel additives will provide 3 to 4% fuel economy. 2. Good driving habits. 3. Properly maintained fuel supply system. 4. Use of computer controlled fuel ... computer controlled ignition system. 6. Use of higher voltage automotive electrical system (42 volts system).
Description : Compare sequential, continuous grouped and simultaneous methods of fuel injection.
Last Answer : Sequential fuel injection (SFI):-Injection of fuel occurs at the same time for all cylinders every revolution of the crankshaft. Therefore, fuel is injected twice within each four-stroke cycle. ... refers to the first three methods of injection, for continuous injection diagram is not needed)
Description : Explain Biodiesel fuel. Give any four applications.
Last Answer : Biodiesel diesel Bio diesel is a vegetable oil or animal fat based diesel fuel. It consists of long chain alkyl esters. It is made chemically reacting liquids with an alcohol. i) It is a ... diesel with 20% biodiesel) 4.Generatore 5.Air craft engines 6.Heating oil in domestic commercial boiler
Description : Draw block diagram for EDC type fuel pump in diesel engine.
Last Answer : Block diagram for EDC type fuel pump in diesel engine OR
Description : Why fuel does not explode even though fuel pump is fitted in the fuel tank itself.
Last Answer : For the combustion/explosion to take place appropriate air fuel mixture and a source of ignition i.e. spark is required. The electric fuel pump is placed inside the fuel tank and is immersed in the ... not available. So fuel does not explode even though fuel pump is filled in the fuel tank itself
Description : Why pressure regulator is required in fuel supply system of EFI system engine?
Last Answer : 1. In low pressure common rail systems (EFI) that do not require high capacity fuel flow where the fuel injector is mounted on a intake manifold port runner on engine displacing less than 2.0 liters. ... differential pressure between 2.0 and 3.5 bar and allows excess fuel to return to the fuel tank.