In a typical medium speed 4-stroke cycle diesel engine the inlet valve
Opens at 20° before top dead center and closes at 35° after the bottom dead center
Opens at top dead center and closes at bottom dead center
Opens at 10° after top dead center and closes 20° before the bottom dead center
May open or close anywhere
Correct Answer :
A. Opens at 20° before top dead center and closes at 35° after the bottom dead center
Related Questions
The knocking tendency in spark ignition engines may be decreased by
Controlling the air-fuel mixture
Controlling the ignition timing
Controlling the exhaust temperature
Reducing the compression ratio
The pressure and temperature at the end of compression stroke in a petrol engine are of the order of
4-6 kg/cm² and 200-250°C
6-12 kg/cm² and 250-350°C
12-20 kg/cm² and 350-450°C
20-30 kg/cm² and 450-500°C
The ratio of the work obtained at the crankshaft in a given time to the energy supplied during the same time is called
Mechanical efficiency
Overall efficiency
Indicated thermal efficiency
Volumetric efficiency
A fuel of an octane number rating of 75 matches in knocking intensity as a mixture of
75% iso-octane and 25% normal heptane
75% normal heptane and 25% iso-octane
75% petrol and 25% diesel
75% diesel and 25% petrol
In a diesel engine, the duration between the time of injection and ignition, is known as
Pre-ignition period
Delay period
Period of ignition
Burning period
Morse test can be conducted for
Petrol engines
Diesel engines
Multi cylinder engines
All of these
For maximum power generation, the air fuel ratio for a petrol engine for vehicles, is of the order of
9 : 1
12 : 1
15 : 1
18 : 1
The injection pressure in a diesel engine is about
10 bar
100 bar
150 bar
500 bar
The specific fuel consumption per BHP hour for diesel engine is approximately
0.15 kg
0.2 kg
0.25 kg
0.3 kg
The method of determination of indicated power of a multi cylinder spark ignition engine is by the use of
Morse test
Prony brake test
Motoring test
Heat balance test
A gas engine has a swept volume of 300 cm3 and clearance volume of 25 cm3. Its volumetric efficiency is 0.88 and mechanical efficiency is 0.90. The volume of the mixture taken in per stroke is
248 cm3
252 cm3
264 cm3
286 cm3
Which of the following statement is correct regarding normal cetane?
It is a standard fuel used for knock rating of diesel engines
Its chemical name is normal hexadecane
It has long carbon chain structure
All of the above
The ratio of the brake power to the indicated power is called
Mechanical efficiency
Overall efficiency
Indicated thermal efficiency
Volumetric efficiency
The increase of efficiency of a compression ignition engine, as the load decreases, is due to
Higher maximum temperature
Qualitative governing
Quantitative governing
Hit and miss governing
If petrol is used in a diesel engine, then
Low power will be produced
Efficiency will be low
Higher knocking will occur
Black smoke will be produced
The operation of forcing additional air under pressure in the engine cylinder is known as
Scavenging
Turbulence
Supercharging
Pre-ignition
The specific fuel consumption per B.P. hour for a petrol engine is about
0.2 kg
0.25 kg
0.3 kg
0.35 kg
The air standard efficiency of an I.C. engine depends on
Fuel used
Speed of engine
Compression ratio
None of these
The exhaust valve in a four stroke cycle petrol engine
Opens at 50° before bottom dead centre and closes at 15° after top dead centre
Opens at bottom dead centre and closes at top dead centre
Opens at 50° after bottom dead centre and closes at 15° before top dead centre
May open and close anywhere
In a four stroke cycle diesel engine, the exhaust valve
Opens at 30° before bottom dead centre and closes at 10° after top dead centre
Opens at 30° after bottom dead centre and closes at 10° before top dead centre
Opens at bottom dead centre and closes at top dead centre
May open and close anywhere
Fuel oil consumption guarantees for I .C. engine are usually based on
Low heat value of oil
High heat value of oil
Net calorific value of oil
Calorific value of fuel
Polymerisation is a chemical process in which molecules of a compound become
Larger
Slowed down
Smaller
Liquid
A 75 cc engine has following parameter as 75 cc
Fuel tank capacity
Lube oil capacity
Swept volume
Cylinder volume
The ratio of the volume of charge admitted at N.T.P. to the swept volume of the piston is called
Mechanical efficiency
Overall efficiency
Volumetric efficiency
Relative efficiency
The process of breaking up or a liquid into fine droplets by spraying is called
Vaporisation
Carburetion
Ionisation
Atomisation
A diesel engine has
One valve
Two valves
Three valves
Four valves
The probability of knocking in diesel engines is increased by
High self ignition temperature
Low volatility
Higher viscosity
All of these
The delay period in compression ignition engines depends upon
Temperature and pressure in the cylinder at the time of injection
Nature of the fuel mixture strength
Relative velocity between the fuel injection and air turbulence pressure of residual gases
All of the above
The temperature of interior surface of cylinder wall in normal operation is not allowed to exceed
80°C
120°C
180°C
240°C
The correct mixture strength (by weight) for petrol is about
14.6 : 1
18.5 : 1
20.4 : 1
22.6 : 1