單項選擇題In a turbocharged four-stroke/cycle diesel engine, the exhaust valve remains open until after top dead center and the intake valve opens before top dead center to（）.

A.produce a scavenging effect in the combustion space
B.equalize cylinder and exhaust manifold pressures
C.alleviate the difference in valve size between the intake and exhaust
D.flush out condensate that collects after each compression stroke


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1.單項選擇題Early injection timing is indicated by （）.

A.high exhaust temperature and low firing pressure
B.high exhaust temperature and high firing pressure
C.low exhaust temperature and low firing pressure
D.low exhaust temperature and high firing pressure

2.單項選擇題A faulty injection in one cylinder of an operating diesel engine can be located by （）

A.cutting out individual injectors and noting engine performance
B.checking lube oil temperature
C.checking cam position
D.using a timing light

3.單項選擇題What harmful condition can result if a diesel engine is operated at very light loads for long periods of time?（）

A.increased carbon buildup
B.burning of intake valves
C.excessive firing pressures
D.increased fuel consumption

4.單項選擇題Turbocharged four-stroke/cycle diesel engines utilize valve overlap for（）.

A.improving cylinder scavenging
B.preheating the combustion chamber
C.reducing air charge density
D.preventing valve wear

5.單項選擇題Operating a propulsion diesel engine at less than 30% of designed normal load for prolonged periods will result in （）.

A.decreased fuel consumption per brake horsepower
B.more complete cylinder scavenging
C.extended valve life
D.carbon formation on combustion chamber surfaces