During idling, a petrol engine requires _________ mixture.
Lean
Rich
Chemically correct
None of these
Correct Answer :
B. Rich
Related Questions
The injection pressure in a diesel engine is about
10 bar
100 bar
150 bar
500 bar
In a four stroke cycle petrol engine, the inlet valve
Opens at top dead centre and closes at bottom dead centre
Opens at 20° before top dead centre and closes at 40° after bottom dead centre
Opens at 20° after top dead centre and closes at 20° before bottom dead centre
May open or close anywhere
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
Scavenging is usually done to increase
Thermal efficiency
Speed
Power output
Fuel consumption
Installation of supercharger on a four cycle diesel engine can result in the following percentage increase in power
Up to 35%
Up to 50%
Up to 75%
Up to 100%
Which of the following fuel has little tendency towards detonation?
Benzene
Iso-octane
Normal heptane
Alcohol
All heat engines utilize
Low heat value of oil
High heat value of oil
Net calorific value of oil
Calorific value of fuel
The theoretically correct air fuel ratio for petrol engine is of the order of
6 : 1
9 : 1
12 : 1
15 : 1
A two stroke cycle engine gives ________ the number of power strokes as compared to the four stroke cycle engine, at the same engine speed.
Half
Same
Double
Four times
It the temperature of intake air in IC engines is lowered, then its efficiency will
Increase
Decrease
Remain same
Increase up to certain limit and then decrease
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
In a petrol engine, if diesel is used, then the engine will
Not run
Run more efficiently
Run at high speed
Explode
A supercharged engine as compared to an ordinary engine
Is lighter
Requires smaller foundations
Consumes less lubricating oil
All of these
Which of the following medium is compressed in a Diesel engine cylinder?
Air alone
Air and fuel
Air and lub oil
Fuel alone
The ignition quality of petrol is expressed by
Cetane number
Octane number
Calorific value
All of these
The knocking tendency in compression ignition engines for a given fuel will be
Enhanced by decreasing compression ratio
Enhanced by increasing compression ratio
Dependent on other factors
None of the above
The maximum temperature in the I.C. engine cylinder is of the order of
500-1000°C
1000-1500°C
1500-2000°C
2000-2500°C
A supercharged engine as compared to an ordinary engine
Requires smaller foundation
Is lighter
Consumes less lubricating oil
All of these
A 75 cc engine has following parameter as 75 cc
Fuel tank capacity
Lube oil capacity
Swept volume
Cylinder volume
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 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
A diesel engine has
One valve
Two valves
Three valves
Four valves
In a typical medium speed 4-stroke cycle diesel engine
Compression starts at 35° after bottom dead center and ends at top dead center
Compression starts at bottom dead center and ends at top dead center
Compression starts at 10° before bottom dead center and, ends just before top dead center
May start and end anywhere
A diesel engine, during suction stroke, draws
Air only
Diesel only
A mixture of diesel and air
None of these
When crude oil is heated, then which of the following hydrocarbon is given off first?
Kerosene
Gasoline
Paraffin
Natural gas
Which of the following is false statement? Excess quantities of sulphur in diesel fuel are Objectionable because it may cause the following
Piston ring and cylinder wear
Formation of hard coating on piston skirts
Oil sludge in the engine crank case
Detonation
The probability of knocking in diesel engines is increased by
High self ignition temperature
Low volatility
Higher viscosity
All of these
Solid fuel fabricated into various small shapes, which are assembled to form fuel elements, is in the form of
Plates
Pallets
Pins
All of these
The thermal efficiency of a standard Otto cycle for a compression ratio of 5.5 will be
25 %
50 %
70 %
100 %
Number of working strokes per min. for a four stroke cycle engine are _________ the speed of the engine in r.p.m.
Equal to
One-half
Twice
Four-times