A diesel engine has compression ratio from
6 to 10
10 to 15
15 to 25
25 to 40
Correct Answer :
C. 15 to 25
Related Questions
Air fuel ratio at which a petrol engine cannot work is
8 : 1
10 : 1
15 : 1
20 : 1 and less
The mechanical efficiency (ηm) of the engine is given by
ηm = B.P/I.P
ηm = I.P/B.P
ηm = (B.P × I.P)/100
None of these
The thermal efficiency of diesel engines on weak mixtures is
Unaffected
Lower
Higher
Dependent on other factors
The firing order in an I.C. engine depends upon
Arrangement of the cylinders
Design of crankshaft
Number of cylinders
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
Compression loss in I.C engines occurs due to
Leaking piston rings
Use of thick head gasket
Clogged air inlet slots
All of the above
The maximum propulsive efficiency of a turbojet engine is at a speed of
1000 km/h
2000 km/h
2400 km/h
3000 km/h
The sensing element in the control system of nuclear reactors measures the _________ of the neutron flux in the reactor.
Temperature
Volume
Density
None of these
The ignition of the charge by some hot surface within the engine before the passage of spark is called
Pre-ignition
Detonation
Ignition delay
Auto-ignition
A supercharged engine as compared to an ordinary engine
Is lighter
Requires smaller foundations
Consumes less lubricating oil
All of these
Thermal efficiency of a two stroke cycle engine is ________ a four stroke cycle engine.
Equal to
Less than
Greater than
None of these
A spark plug gap is kept from
0.3 to 0.7 mm
0.2 to 0.8 mm
0.4 to 0.9 mm
0.6 to 1.0 mm
The thermal efficiency of petrol and gas engines is about
15 %
30 %
50 %
70 %
A diesel engine, during suction stroke, draws
Air only
Diesel only
A mixture of diesel and air
None of these
The increase of cooling water temperature in petrol engine will __________ the knocking tendency.
Not effect
Decrease
Increase
None of these
In a four stroke cycle diesel engine, the inlet valve
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
Opens at top dead centre and closes at bottom dead centre
May open and close anywhere
The knocking in spark ignition engines can be reduced by
Retarding the spark
Increasing the engine speed
Both (A) and (B)
None of these
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 four stroke cycle diesel engine, the compression
Starts at 40° after bottom dead centre and ends at 10° before top dead centre
Starts at 40° before top dead centre and ends at 40° after top dead centre
Starts at top dead centre and ends at 40° before bottom dead centre
May start and end anywhere
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
In a four stroke cycle engine, the sequence of operations is
Suction, compression, expansion and exhaust
Suction, expansion, compression and exhaust
Expansion, compression, suction and exhaust
Compression, expansion, suction and exhaust
Which of the following is not an interns combustion engine?
2-stroke petrol engine
4-stroke petrol engine
Diesel engine
Steam turbine
If V₁ is the jet velocity and V₀ is the vehicle velocity, then propulsive efficiency of a turbojet engine is
V₁/(V₀ + V₁)
V₀/(V₀ + V₁)
2V₀/(V₀ + V₁)
2V₁/(V₀ + V₁)
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
The inlet value of a four stroke cycle I.C engine remains open for nearly
180°
125°
235°
200°
Which of the following fuel detonates readily?
Benzene
Iso-octane
Normal heptane
Alcohol
The pressure at the end of compression, in petrol engines, is approximately
10 bar
20 bar
25 bar
35 bar
A 5 BHP engine running at full load would consume diesel of the order of
0.3 kg/hr
1 kg/hr
3 kg/hr
5 kg/hr
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
The effective inhibitor of pre-ignition is
Alcohol
Water
Lead
None of these