单选题Maximum horsepower of a diesel engine is attained （）.A when the engine RPM is pulled down by overloadB at rated engine RPMC at 95 % of rated engine RPMD at 95 % of a properly adjusted governor RPM with the engine under full load

Any increase in the exhaust back pressure of a four-stroke/cycle diesel enginewill( ).

A.reduce engine horsepower output

B.aid in silencing the exhaust noise

C.increase the mean effective pressure

D.contribute to effective cylinder scavenging

Which of the following reasons represents why the designed compression ratio of a gasoline engine is lower than that of a diesel engine?

A.compression must be low for effective spark ignition

B.compression must be low for required horsepower and torque generation

C.compression must be low to prevent pre-ignition

D.compression must be low to have effective pre-ignition

If all other conditions such as bore, stroke, speed, and mean effective pressures are equal, a two stroke/cycle diesel engine will develop approximately

A.the same indicated horsepower as a four-stroke/cycle engine

B.twice the indicated horsepower as a four-stroke/cycle engine

C.one half the indicated horsepower as a four-stroke/cycle engine

D.one power stroke for every two crankshaft revolutions

A diesel engine experiences a sudden loss in speed, accompanied by black exhaust smoke, with the fuel rack at maximum, and speed remaining below normal .the probable ___.

A.engine overload

B.leaky valves

C.stuck or broken piston rings

D.low air injection pressure