The reference fuels for knock rating of spark ignition engines would include
Iso-octane and alpha-methyl naphthalene
Normal octane and aniline
Isooctane and normal hexane
Normal heptane and isooctane
Correct Answer :
D. Normal heptane and isooctane
Related Questions
The fuel in diesel engine is normally injected at pressure of
5-10 kg/cm²
20-25 kg/cm²
60-80 kg/cm²
90-130 kg/cm²
The thermodynamic cycle on which the petrol engine works, is
Otto cycle
Joule cycle
Rankine cycle
Stirling cycle
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
An hmh flame speed is obtained in diesel engine when air fuel ratio is
Uniform throughout the mixture
Chemically correct mixture
About 35% of rich mixture
About 10% of rich mixture
In order to mix air and petrol in the required proportion and to supply it to the engine during suction stroke, then _________ is employed.
Fuel pump
Injector
Carburettor
None of these
A diesel engine has
1 valve
2 valves
3 valves
4 valves
A supercharged engine as compared to an ordinary engine
Is lighter
Requires smaller foundations
Consumes less lubricating oil
All of these
In a typical medium speed 4-stroke cycle diesel engines
Exhaust valve opens at 35° before bottom dead centre and closes at 20° after top dead centre
Exhaust valve opens at bottom dead centre and closes at top dead centre
Exhaust valve opens just after bottom dead centre and closes just before top dead centre
May open and close anywhere
Detonation is harmful due to
Increase in the rate of heat transfer, there is a reduction in the power output and efficiency of the engine
Excessive turbulence which removes most of the insulating gas boundary layer from the cylinder walls
High intensity of knock causes crankshaft vibration and the engine runs rough
None of the above
The purpose of testing an internal combustion engine is
To determine the information, which cannot be obtained by calculations
To conform the data used in design, the validity of which may be doubtful
To satisfy the customer regarding the performance of the engine
All of the above
The air-fuel ratio of the petrol engine is controlled by
Carburettor
Injector
Governor
None of these
The cam shaft of a four stroke I.C. engine running at 1500 rpm will run at
1500 rpm
750 rpm
3000 rpm
Any value independent of engine speed
A petrol engine has compression ratio from
6 to 10
10 to 15
15 to 25
25 to 40
The effective inhibitor of pre-ignition is
Alcohol
Water
Lead
None of these
The temperature of interior surface of cylinder wall in normal operation is not allowed to exceed
80°C
120°C
180°C
240°C
In a naturally aspirated diesel engine, the air is supplied by
A supercharger
A centrifugal blower
A vacuum chamber
An injection tube
In a typical medium speed, 4-stroke cycle diesel engine
Fuel injection starts at 10° before to dead center and ends at 20° after tor dead center
Fuel injection starts at top dead center and ends at 20° after top dead center
Fuel injection starts at just before top dead center and ends just after top dead center
May start and end anywhere
The following volume of air is required for consuming 1 litre of fuel by a four stroke engine
1 m3
5 m3
56 m3
910 m3
A diesel engine is _________ as compared to petrol engine, both running at rated load.
Equally efficient
Less efficient
More efficient
None of these
The term scavenging is generally associated with
2-stroke cycle engines
4-stroke cycle engines
Aeroplane engines
High efficiency engines
Most high speed compression engines operate on
Diesel cycle
Otto cycle
Dual combustion cycle
Special type of air cycle
Air fuel ratio for idling speed of a petrol engine is approximately
1 : 1
5 : 1
10 : 1
15 : 1
The increase of cooling water temperature in petrol engine will __________ the knocking tendency.
Not effect
Decrease
Increase
None of these
Which of the following is not an interns combustion engine?
2-stroke petrol engine
4-stroke petrol engine
Diesel engine
Steam turbine
Gaseous fuel guarantees are based on
Calorific value of oil
Low heat value of oil
High heat value of oil
Mean heat value of oil
Supercharging is the process of
Supplying the intake of an engine with air at a density greater than the density of the surrounding atmosphere
Providing forced cooling air
Injecting excess fuel for raising more loads
Supplying compressed air to remove combustion products fully
For the same power developed in I.C. engines, the cheaper system is
Naturally aspirated
Supercharged
Centrifugal pump
Turbo charger
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 air requirement of a petrol engine during starting compared to theoretical air required for complete combustion is
More
Less
Same
May be more or less depending on engine capacity
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