24 09 16 quiz

Pagina 1

24/09/16 A 4 valve and a 2 valve head with the same bore are compared. The maximum valve lift will be: 1) Higher in the 4 valve engine 2) Higher in the 2 valve engine 3) The same in the two engines 4) The same only if in the 4 valve case equal valve diameters are used Anticipating the exhaust valve opening: 1) The temperature of the exhaust gases decreases 2) The pressure of the exhaust gases decreases 3) The expansion work decreases 4) The combustion process is improved The mechanical efficiency of an IC engine: 1) Does not depend on the engine load 2) Decreases with the increase of the revolution speed 3) Asimptotically approaches 1 4) Improves with the introduction of a volumetric compressor driven by the engine Dual stage turbocharging: 1) Makes use of a single turbine with double entry 2) Requires a double-entry compressor 3) Involves two turbines and one compressor 4) Involves two turbines and two compressors The swirl motion is: 1) Important mainly for SI engines 2) Generated by fuel injection in CI engines 3) Generated by a helical port in the head duct 4) Generated during the exhaust process The wave effect in the intake system: 1) Is important during the expansion stroke 2) Can be correctly exploited at high engine speeds with short pipes 3) Can be tuned to achieve a rarefaction wave on the intake port 4) Does not depend on the intake pipe lenght Constant pressure turbocharging: 1) Does not determine large fluctuations of the turbine efficiency 2) Requires a double-entry compressor 3) Increases the pressure oscillations in a large volume intake manifold 4) Reduces the turbo-lag issue If the intake valve diameter is reduced, we expect that the volumetric efficiency: 1) Will decrease mainly at high speeds 2) Will decrease mainly at low speeds 3) Will decrease…