Examen piston engines
Piston Engines Expert Quiz
Test your knowledge on piston engines with our comprehensive quiz designed for automotive enthusiasts and professionals alike. Dive into 48 engaging questions covering various aspects of diesel and gasoline engine mechanics, emissions, fuel types, and more.
- Evaluate your understanding of engine performance.
- Learn about different fuel properties.
- Discover essential engine technology concepts.
What do we control with the pedal of a Diesel engine:
Equivalence ratio
Throttle
Efficiency
Amount of cylinders used
What prevents the injection of the fuel
Air-fuel ratio
Balance of the forces
Solenoid
None of the above
Torque generated by the engine depends on
Pressure in the cylinder
Type of fuel
Heat in the engine
Pedal
A higher octane number for gasoline results to
Higher resistance to knock
Lower resistance to knock
Higher ignition delay
Lower ignition delay
What is the advantage of pilot injection in Diesel engines:
Lower risk of knock
Increase pollutant
Cleaning combustion chamber
Increase torque
Which one of these gases are pollutants (a gas that is not the expected product of combustion)
HC
NOx
CO
CO2
N2
What conditions should I work with for three-way catalyst:
High temperature
Lambda one
High O2 concentration
None of the above
What are the drawbacks of HCCI?
Increased NOx emissions
Lower efficiency
Smaller operating range (noise)
Control
The compression ratio of a SI engine is increased. Which are some of the consequences?
Knock sensitivity increases
Efficiency will increase
Temperature and pressure at end of compression stroke will be higher
NOx emissions will be lower
Which are the advantages of a 2 stroke SI engine?
Larger specific power
Lower fuel consumption
Torque is more constant than the torque of a comparable 4S
Easier cooling of the engine
Which is the type of cylinder arrangement in the following figure? 1 answer possible!
In-line
V-type
Radial
Flat 7
Which are the advantages of a cross-head engine?
Can operate at higher RPM
Is cheaper in construction
Blow-by is decreased
More reliable and longer life
A CI engine with constant torque of 4000Nm and operates at 500rpm, what is the power delivered?
66 kW
209 kW
33 kW
2000 kW
In summer time the vapour pressure of petrol will be…?
Increased to avoid vapour lock
Increased to have a higher RON
Decreased to avoid vapour lock
Decreased to have better evaporation
A high cetane number results in…?
Larger diesel knock
Smoother combustion
Smaller ignition delay
Higher combustion pressures
Is it necessary for optimal combustion to change the pre-ignition angle if instead of a RON95 a RON 98 fuel is used ?
No, as the pia is a fixed value under all circumstances
Yes, the pia should be increased
Yes, the pia should be decreased
No, as the pia does not depend on the RON
What are the design requirements for an SI combustion chamber?
Large bore
Low turbulence degree
Small distance between spark plug and exhaust valves
Good cooling
Which one is/are true for an EGR engine?
Lower fuel consumption
Torque is more constant than the torque of a comparable 4S engine
Easier cooling of the engine
What should the size of droplets in a CI engine chamber look like?
As small as possible to accelerate heating and ignition
As large as possible to increase the injection pressure
As large as possible to increase the penetration depth
As small as possible to reduce the ignition delay
Diesel knock can be decreased by following actions:
Using glow plug heating when starting the engine
Using a fuel with a low CN
Injection of fuel in different stages (i.e. With a pilot injection)
Increase the compression ratio
How is the soot burned in the soot or particulate filter?
Soot is continuously burned
It’s burned using a spark plug as ignition source
It’s burned by the high pressure difference along the soot filter
The soot is burned when the pressure difference along the soot filter becomes too high by post-injection of fuel in the cylinder or in the exhaust system
Direct injection is more efficient because:
It gives a better volumetric efficiency
It reduces the emissions
It has a fast injection
The rotation speed of SI engines is larger than the rotation speed of comparable CI engines. Why ?
Larger pre-ignition angle of SI engines
Lighter moving components are used in SI engines
Higher compression ratio of SI engines
Ignition delay of diesel fuel
In a 4S cycle the exhaust valve is opened before the piston reaches the BDC during the expansion stroke. Which are the advantages of opening the exhaust valve earlier ?
Better scavenging of the cylinder
No back-pressure during exhaust stroke
Better cooling of exhaust valve
Increase of volumetric efficiency
Which are the main reasons why a carburetor is not used anymore in SI traction engines ?
Less reliable
Constant A/F ratio cannot be obtained
Unequal filling of the cylinders of the engine
Higher costs
Knock sensitivity in SI engines will increase if
RON is decreased
Engine load is increased
Compression ratio is decreased
Pre-ignition angle is increased
A 3 cylinder line engine
Is completely balanced for forces but the primary and secondary moments should be corrected by a balancing shaft at rotation speed and twice the rotation speed.
Is completely balanced for forces and moments
Is completely balanced for forces but the secondary moments should be corrected by balancing shafts at twice the rotation speed
Is completely balanced for moments but the secondary forces should be corrected by balancing shafts at twice the rotation speed
For the same work output and maximum pressure, at a given regime
CI will have an higher efficiency
SI and CI engine will have the same torque
SI and CI engine will have the same fuel consumption
SI will have an higher efficiency
For a constant speed driving the lowest fuel consumption is achieved ...
When the torque output is near the maximum torque
At highest rotation speed
At lowest rotation speed
When the torque reserve is minium
Using a parallel/serial turbocharger configuration, with respect to a single larger one
Can only be applied to SI engine
Allows a lower response time
Allows an higher maximum power
Simplify the engine
What are the advantages of more complex injection patterns in Diesel engines (multiple answers are possible)
Decrease fuel consumption
Lower risk of knock
Cooling inlet valve
Light up the PM filter for regeneration
Real Driving Emission were introduced to
Use the engine in a non predictable way
Measure NOx
Measure CO2 emissions
Avoid cycle detection
In a typical distillation curve, the diesel comes
Before the gasoline
After the gasoline
Before the kerosene
After the kerosene
When converting gasoline SI engine to natural gas
No spark plug is needed
The compression ratio can be increased
One has to use direct injection
The compression ratio must be decreased
The connecting rod
Connects the piston to the crankshaft
Connects the piston to the valves
Connects the piston to the cylinder wall
Connects the valves to the crankshaft
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