Which one of the followings is a wrong statement?
Valve timing diagram shows the correct crank positions corresponding to opening and closing of the valves
Valve overlap represents the angle during which both the inlet and exhaust valves remain open
For the same engine speed and cylinder volume, the power developed by a four-stroke engine is two times the power output from a two-stroke engine
Scavenging is the process of removal of burnt gases from the engine cylinder by the fresh charge coming into the cylinder form the crankcase
The float in the carburetor of a petrol engine controls
Flow rate of air
Flow rate of fuel
Flow rate of air-fuel mixture
Level of the petrol in the float chamber
All of the following statements are correct except
A carburetor prepares a homogeneous air-fuel mixture by atomizing and vaporizing the fuel
Vacuum at the throat of venture sucks the fuel through the fuel jet
Throttle valve controls the supply of air fuel mixture
Choke is kept open when cranking a cold engine for starting
In the fuel system of a petrol engine
Air and petrol are mixed in the ratio of about 15 parts of petrol to one part of air
Air pressure is reduced when the air passes through a venturi
Air should be prevented from entering the tank
Air entering the induction system through a brokent gasket at the manifold would give a condition called rich mixture
Lean air fuel mixture is required for
Starting
Idling
Cruising
Acceleration
An adjustment in the setting of a carburetor has been made for running the petrol engine at mean sea level. What will be the quality of mixture supplied to the engine if now it is made to operate at high altitudes
Rich
Lean
No change in the quality of mixture supplied
Ther will not be any flow of petrol from the cold chamber.
What identifies the anti-knock quality of diesel fuel?
SAE number
API gravity
Octane number
Cetane number
Performance index
Cetane number of a fuel is a measure of its
Viscosity
Volatility
Ingnition quality
API specific gravity
Which fuel has a cetane number fo hundred?
Cetane
Ethyl fluid
-methyl naphthalene
Normal heptane
The two reference fuels used for cetane rating are
Cetone and iso-octane
Cetone and tetra ethyl lead
Cetane and n-heptane
Cetane and a-methyl naphthalene
The cetane number of diesel fuel is determined by conducting test on a blend of cetane with
n-heptane
Ethyl fluid
-methyl naphthalene
Dicholoro-fluoro-methane
Cetane is a straight chain paraffin with formula
C10H20
C14H30
C12H24
C16H34
The commercially available diesel fuels in India have a cetane number of
20-30
45-50
60-75
85-90
Consider the following statements regarding n-octane
it is a standard fuel used for knock rating of diesel engines
its chemical name is n-hexadecone ]
it is a saturated hydrocarbon of partition series
it has along carbon chain structure
Which of the above statements are correct?
1,3 and 4
1, 2 and 3
1,2 and 4
2, 3 and 4
The phenomenon of pre-ignition
Always occurs in diesel engines
Never occurs in diesel engines
Always occurs in petrol engines
Increase the power output engines
All of the following statements are correct, except
The detonation follows the spark while preignition proceeds it
Doping refers to the addition of certain additives to petrol to improve its resistance to detonation
The paraffin fuels give less detonating trouble than the aromatic fuels
Factors tending to increase detonation in S.I.engine tend to reduce knocking in C.I. engines
The spark engine fuels in order of increasing detonation tendency are:
Aromatics, napthenes, paraffins
Paraffins, aromatics, napthenes
Napthenes, paraffins, aromatics
Aromatics, paraffins, napthenes
The primary function of lubrication in an automobile engine is to
Reduce friction between moving parts
Remove heat from the cylinder and bearings
Provide cushion to the moving parts against shocks and vibrations
Avoid leakage of charge by providing effective sealing
Which engine part needs to be only sparingly lubricated?
Main bearings
Camshaft bearings
Guides and stems of valves
Piston and cylinder
The automobile gears are generally made of
Cast iron
Mild steel
Alloy steel
Cast steel