Antiknock for compression ignition engines is
Napthene
Tetra ethyl lead
Amyl nitrate
Hexadecane
Correct Answer :
C. Amyl nitrate
Related Questions
The output of a diesel engine can be increased without increasing the engine revolution or size in following way
Feeding more fuel
Heating incoming air
Scavenging
Supercharging
The thermal efficiency of petrol and gas engines is about
15 %
30 %
50 %
70 %
In a cycle, the spark lasts roughly for
1 sec
0.1 sec
0.01 sec
0.001 sec
The reflectivity depends upon
Geometry of the reflector
Energy of neutrons
Properties of the reflector
All of these
The normal heptane (C7H16) is given a rating of ________ octane number.
0
50
100
120
As compared to air standard cycle, in actual working, the effect of variation in specific heats is to
Increase maximum pressure and maximum temperature
Reduce maximum pressure and maximum temperature
Increase maximum pressure and decrease maximum temperature
Decrease maximum pressure and increase maximum temperature
Crankcase explosion in I.C. engines usually occurs as
First a mild explosion followed by a bi explosion
First a big explosion followed by a mil explosion
Both mild and big explosions occurs simultaneously
Never occurs
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
The pressure at the end of compression in the case of diesel engine is of the order of
6 kg/cm
12 kg/cm
20 kg/cm
35 kg/cm
Most high speed compression engines operate on
Otto cycle
Diesel cycle
Dual cycle
Carnot cycle
The scavenging efficiency of a four stroke cycle diesel engine is
Below 50%
Between 50 and 85%
Between 85 and 95%
Between 95 and 100%
The thermal efficiency of a petrol engine is _________ as compared to diesel engine.
Same
Less
More
None of these
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 volumetric efficiency of a well designed engine may be
30 to 40 %
40 to 60 %
60 to 70 %
75 to 90 %
The air-fuel ratio in petrol engines is controlled by
Controlling valve opening/closing
Governing
Injection
Carburetion
The voltage required to produce a spark across the gap, between the sparking points is
2000 to 4000 volts
4000 to 6000 volts
6000 to 10,000 volts
10,000 to 12,000 volts
A higher compression ratio causes
Pre-ignition
Increase in detonation
Acceleration in the rate of combustion
Any one of these
The magneto in an automobile is basically
Transformer
D.C. generator
Capacitor
Magnetic circuit
In petrol engines, the delay period is of the order of
0.001 second
0.002 second
0.003 second
0.004 second
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 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
As a result of detonation in an I.C. engine, following parameter attains very high value
Peak pressure
Rate of rise of pressure
Rate of rise of temperature
Peak temperature
The accumulation of carbon in a cylinder results in increase of
Clearance volume
Volumetric efficiency
Ignition time
Effective compression ratio
If the compression ratio of an engine working on Otto cycle is increased from 5 to 7, the percentage increase in efficiency will be
2 %
4 %
8 %
14 %
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
The specific fuel consumption of a petrol engine compared to diesel engine of same H.P. is
Same
More
Less
Less or more depending on operating conditions
The temperature of interior surface of cylinder wall in normal operation is not allowed to exceed
80°C
120°C
180°C
240°C
A diesel engine has
1 valve
2 valves
3 valves
4 valves
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 ratio of indicated thermal efficiency to the corresponding air standard cycle efficiency is called
Net efficiency
Efficiency ratio
Relative efficiency
Overall efficiency