Thermal efficiency of a two stroke cycle engine is ________ a four stroke cycle engine.
Equal to
Less than
Greater than
None of these
Correct Answer :
B. Less than
Related Questions
The thermal efficiency of a diesel cycle having fixed compression ratio, with increase in cut-off ratio will
Increase
Decrease
Be independent
May increase or decrease depending on other factors
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
A higher compression ratio causes
Pre-ignition
Increase in detonation
Acceleration in the rate of combustion
Any one of these
The fuels in order of decreasing knock tendency for spark ignition engines are
Paraffin, aromatic, napthene
Paraffin, napthene, aromatic
Napthene, aromatics, paraffin
Napthene, paraffin, aromatic
For the same power developed in I.C. engines, the cheaper system is
Naturally aspirated
Supercharged
Centrifugal pump
Turbo charger
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 inlet valve of a four stroke cycle internal combustion engine remains open for
130°
180°
230°
270°
In a four stroke cycle petrol engine, the pressure inside the engine cylinder during the suction stroke is __________ the atmospheric pressure.
Equal to
Below
Above
None of these
In the opposed piston diesel engine, the combustion chamber is located
Above the piston
Below the piston
Between the pistons
There is no such criterion
Morse test can be conducted for
Petrol engines
Diesel engines
Multi cylinder engines
All of these
The air-fuel ratio of the petrol engine is controlled by
Carburettor
Injector
Governor
None of these
Iso-octane (C8H18) has octane number of
0
50
100
120
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
If the speed of the engine is increased, the indicated power will
Increase
Decrease
Remain same
None of these
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
In petrol engines, the delay period is of the order of
0.001 second
0.002 second
0.003 second
0.004 second
The theoretically correct mixture of air and petrol is
10 : 1
15 : 1
20 : 1
25 : 1
The brake power (B.P.) of the engine is given by (where W = Brake load or dead load in newtons, l = Length of arm in metres, N = Speed of engine in r.p.m., S = Spring balance reading in newtons, D = Dia. of brake drum in metres, and d = Dia. of rope in metres)
B.P = (Wl × 2πN)/60 watts
B.P = [(W - S) πDN]/60 watts
B.P = [(W - S) π (D + d) N]/60 watts
All of these
The thermal efficiency of a petrol engine is _________ as compared to diesel engine.
Same
Less
More
None of these
Pick up the wrong statement about supercharging
Supercharging reduces knocking in diesel engines
There can be limited supercharging in petrol engines because of detonation
Supercharging at high altitudes is essential
Supercharging results in fuel economy
The function of a distributor in a coil ignition system of I.C. engines is
To distribute spark
To distribute power
To distribute current
To time the spark
The actual volume of fresh charge admitted in 4-stroke petrol engine is
Equal to stroke volume
Equal to stroke volume and clearance volume
Less than stroke volume
More than stroke volume
The ratio of indicated thermal efficiency to the corresponding air standard cycle efficiency is called
Net efficiency
Efficiency ratio
Relative efficiency
Overall efficiency
The inlet value of a four stroke cycle I.C engine remains open for nearly
180°
125°
235°
200°
Which one of the following engines will have heavier flywheel than the remaining ones?
30 kW four-stroke petrol engine running at 1500 r.p.m.
30 kW two-stroke petrol engine running at 1500 r.p.m.
30 kW two-stroke diesel engine running at 750 r.p.m.
30 kW four-stroke diesel engine running at 750 r.p.m.
Pick up the false statement
Thermal efficiency of diesel engine is about 34%
Theoretically correct mixture of air and petrol is approximately 15:1
High speed compression engines operate on dual combustion cycle
S.I. engines are quality governed engines
Pick up the wrong statement
2-stroke engine can run in any direction
In 4-stroke engine, a power stroke is obtained in 4-strokes
Thermal efficiency of 4-stroke engine is more due to positive scavenging
Petrol engines occupy more space than diesel engines for same power output
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
For the same compression ratio
Otto cycle is more efficient than the Diesel
Diesel cycle is more efficient than Otto
Both Otto and Diesel cycles are, equally efficient
Compression ratio has nothing to do with efficiency
The operation of forcing additional air under pressure into the engine cylinder is known as
Supercharging
Carburetion
Turbulence
Delay period