Recent questions tagged advanced-automobile-engines

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 : 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 : Explain Delay Period in detail.

Last Answer : Delay period: Ignition delay period is the time period between start of injection and start of combustion, has a great influence on the correct optimization of a diesel engine. The knock phenomenon ... with air, and mixture rose in temperature. Pre-flame reactions occur during chemical delay  

Description : What are the advantages of V.V.T?

Last Answer : Advantages of V.V.T (Variable Valve Timing) 1) It improves performance of an engine. 2) It increases engine flexibility under different conditions. 3) It improves fuel economy. 4) It makes precise handling of engine valve. 5) It lowers the exhaust emission. 6) It increases torque.

Description : Sketch and Explain F-head combustion chamber.

Last Answer : In F-head combustion chamber one valve is in head and other in the block. This design is a compromise between L-head and I head combustion chambers. Advantages are : High volumetric ... This design is the complex mechanism for operation of valves and expensive special shaped piston. 

Description : Explain working of LPG kit with labeled block diagram.

Last Answer : Working of LPG Kit: LPG Tank: It is used to store the LPG at 10 bar Filler Valve: It allows the LPG into the tank while feeling. Pressure Relief Valve: It is used to limit ... regulator Mixer / gas injection which flows the LPG into the combustion chamber  Block diagram:  

Description : Explain engine design modification parameter to control emissions.

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 ... tolerances and using special type of carburetors. This also includes fuel injection in manifold.  

Description : Explain the working computer controlled EGR system.

Last Answer : Exhaust Gas recirculation: EGR System is control by the ECM. A pressure sensor monitors the exhaust system pressure. The sensor signals this information of pressure to the ECM. The ECM sends the signal ... open and close the EGR valve. Thus it controls the amount of exhaust gas recalculated.

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 : 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 : State the effect of compression ratio and turbulence on ignition lag.

Last Answer : Effect of engine variables on ignition lag  1) Compression ratio: A higher compression ratio increases the pressure and temperature of the working mixture and decreases the concentration of the residual gases. ... . For this reason. It becomes necessary to advance the spark timing at higher speed. 

Description : What is diesel smoke? State two methods to control diesel smoke.

Last Answer : Diesel smoke: Smoke is defined as visible products of combustion, is due to poor combustion. It originates early in the combustion. Rich fuel-air mixture & at pressures developed in diesel ... manifold. This shortens the delay period- curbs thermal cracking which is responsible for soot format

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 : Explain the working of series hybrid vehicle.

Last Answer : Series-Hybrid vehicle In Series Hybrid vehicles, the Internal Combustion Engine (ICE) drives a generator, which charges the battery and supplies current to the electronically controlled motor. The electric motor ... have to be rated to the maximum power. It has low overall system efficiency.

Description : Explain the pollutants from gasoline engine

Last Answer : 1. Hydrocarbon (HC):-They play an important role in forming NO2 and O3 which are health and environmental hazard.  2. Carbon Monoxide (CO): CO is a highly poisonous gas that can cause dizziness, ... effect, NO2 is a very toxic gas and contributes to the formation of smog, ozone, and acid rain.

Description : What does VTEC stands for? State advantages of it.

Last Answer : VTEC stands for Variable valve timing and electronic lift control. In VTEC, the valve timing and the valve lift is controlled using ECU to provide efficient breathing of engine and efficient performance of ... GDI is capable of using very lean mixture i.e. 65:1 while using VTEC Improve drivability

Description : Explain the following properties i) Pour point ii) Viscosity iii) Ignition quality iv) Fire point

Last Answer : i. Pour point: Pour point is the temperature below which the entire mass of fuel, solid or liquid together, freeze and thus cause flow of fuel impossible. Pour point is usually 5 to 10 °C below ... is the temperature at which the flash will sustain itself as a steady flame for at least five seconds.

Description : With neat labeled figure, explain the working of any two position of PCV (positive crank case ventilation) valve.

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 where as the spring pressure tends to keep it open.(Fig a ... back seat sealing the inlet and crankcase is protected from the back fire.(Fig d).

Description : Write the functions of actuators

Last Answer : 1. An actuator is a component of an engine that is responsible for moving or controlling parts of an engine. 2. An actuator requires a control signal and a source of energy. The control ... movement by converting one kind of motion, such as rotary motion, into another kind, such as linear motion

Description : Define detonation and surface ignition

Last Answer : 1) Detonation  Detonation is auto-ignition of last part of homogeneous charge occurring near the end of combustion, before the flame front reaches it. In auto- ignition, the burning is almost ... spark plug or glowing combustion chamber i.e. any means other than the normal spark discharge.

Description : List and Explain two type of diesel smoke. Explain four cause of diesel smoke.

Last Answer : Answer: Two type of diesel smoke 1) Blue-white smoke 2) Black smoke Four cause of diesel smoke:- 1) Blue smoke is due to burning the droplets of lubricating oil in combustion ... because of worn piston rings & cylinder liners & water come in combustion chamber because cracked water jacket.

Description : List three sources of pollutant from gasoline engine. Explain evaporative losses in detail.

Last Answer : Answer: Three sources of pollutant from gasoline engine:- 1) Carburettor losses 2) Crankcase blow-by 3) Engine exhaust emission Evaporative losses:-  1. Carburettor losses: occur due ... due to incomplete combustion, the exhaust gas also contains carbon monoxide, unburnt hydrocarbons (UBHC).

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 : How VGT is beneficial over conventional Turbocharger?

Last Answer : Answer: VGT is beneficial over conventional Turbocharger due to following reasons:- 1) Reduce Turbo Lag 2) Quick Responsive engine 3) Improved fuel efficiency by 20% 4) Accurate boost speed at low ... excessive. So waste gate boost control is not needed. 6) Higher power output at lower speed 

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 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 : 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 : Draw a labeled block diagram of CNG conversion Kit. Describe it’s working

Last Answer : Working of CNG Kit: The Sequential Injection system still has a high pressure tank, filler, filter and regulator, the regulator is different in that it puts out a steady pressure as opposed ... , natural gas temperature sensor and coolant temperature sensor to operate and control the system.  

Description : With the help of neat sketch, describe block diagram of Electronic Diesel Control Unit (EDC).

Last Answer : EDC: The ECU determines the correct quantity of the fuel to be injected based on the inputs and the data in the look up table. The fuel input depends on the rack position and thus ECU ... ECU can also protect the engine against overheating by regulating the maximum quantity of fuel delivered.

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 : 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 : Illustrate idle speed control as an output control function of ECM.

Last Answer : Idle Speed Control as Output function of a ECM: While the engine is being started, or operated, the logic module of Electronic Control Module (ECM) will signal the Stepper motor of Idle Speed Control ( ... control valve stepper motor allows 125 possible valve opening positions.  OR

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 four types of sensors used in MPFI system, state their locations and functions.

Last Answer : Sr. Name Function Location 1 Oxygen Sensor Measuring the quantity of oxygen in exhaust  Located at inlet and outlet side of catalytic converter 2 Mass air flow(MAF ... the combustion process and supplies signal to the ECU. This sensor is fitted on cylinder block.

Description : List four types of combustion chambers used in S.I. engine. Explain any one in detail with neat sketch.

Last Answer : Combustion chambers used in S.I. engine:- 1) T - Head 2) I - Head. 3) F - Head. 4) L - Head 5) Divided combustion chamber. 1. T Head Type Combustion chambers.  This ... and therefore more heat loss. 4. Valve size restricted. 6. Thermal failure in cylinder block also. 

Description : Distinguish between JBI and PFI system

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 injector ... the throttle body Hither power output due to low resistance at intake manifold and higher volumetric efficiency.

Description : With the help of suitable sketch describe the working of pressure regulator.

Last Answer : Working of pressure regulator : The fuel pump provides more fuel than the maximum required by the engine. Fuel not used by the engine is returned to the fuel tank. The fuel rail supplies all injectors. The pressure ... between 2.0 and 3.5 bar and allows excess fuel to return to the fuel tank.

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 : 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 : List out the methods for evaporation control and explain any one.

Last Answer : Methods for evaporation control:- 1. Charcoal Canister System (for Fuel tank and carburetor float bowl emissions 2. Positive Crankcase Ventilation (PCV) System (for crankcase ... crankcase ventilation performance is optimized, while engine performance and drivability remains unaffected.

Description : List down the pollutants from gasoline engine and diesel engine.

Last Answer : Pollutants from gasoline engine:- 1. Hydrocarbons. 2. Carbon Monoxide. 3. Carbon dioxide. 4. Oxides of Nitrogen. Pollutants from diesel engine:- 1. Hydrocarbons 2. Carbon Monoxide. 3. Carbon dioxide. 4. Oxides of Nitrogen. 5. Particulate matters.

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 : Explain VVT mechanism and state any two advantages of it.

Last Answer : Variable valve timing (VVT) is a system for varying the valve opening of an internal combustion engine. This allows the engine to deliver high power, but also to work tractably and efficiently at low power ... handling of engine valve. 5) It lowers the exhaust emission. 6) It increases torque. 

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 : 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 : 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 : Write about need advantages and of limitation in Hybrid vehicles.

Last Answer : Need of Hybrid Vehicle 1. To increase fuel efficiency. 2. To reduce gaseous emission. 3. To increase acceleration capability. 4. To reduce noise emission. 5. To reduce fuel consumption Advantages 1. ... 1. Less power. 2. Can be expensive. 3. Poorer handling. 4. Higher maintenance cost.

Description : List any four advantages of CRDI system and write its operation.

Last Answer : Advantages of CRDI System: 1. Deliver 25% more power and torque than the normal direct injection engine. 2. Lower levels of noise and vibration. 3. Lower emissions. 4. Lower ... activating solenoid valve, whereas the injection rate can be modified by controlling the nozzle needle movement. 

Description : State the difference between turbocharger & VGT used in diesel engine.

Last Answer : Difference between turbocharger and VGT Sr. No. Parameter Turbocharger VGT 1 Fuel efficiency Lower fuel efficiency as compared to VGT Improved fuel efficiency by20% 2 ... required. 6 Engine response Sluggish response at low speeds Quick responsive engine