Discuss why

$7.$ A four$-$stroke cycle engine may or may not have a pressure boost in the intake

system.

$8.$ The two$-$stroke cycle engine must always have an intake pressure boost.

$9.$ The marine engine operates on a two$-$stroke cycle.

$10.$ In compression ignition engines, no fuel is added to the incoming air, so that

compression is done on air only.

$11.$ In two$-$stroke SI engines, scavenging lasts until piston passes BDC and closes intake and exhaust ports.

$12.$ In CI engines, combustion occurs at constant pressure.

$13.$ Knock usually occurs at WOT when the engine is loaded.

$14.$ Knock may occur in the termination stage of combustion.

$15.$ For the same input conditions and same compression ratio diesel cycle is less than dual and Otto cycles.

$16.$ Race cars are sometimes operated with a lean mixture.