increase back pressure during the exhaust process
facilitate periodic replacement of the valves
reduce the pumping loss associated with scavenging
reduce tension on valve springs
第1题：
Which of the following conditions could contribute to the cracking of a diesel engine cylinder head?
A.Leaking seal ring
B.Insufficient heat transfer from the exhaust valves
C.Blocked cooling water passages to the head
D.Excessive scavenging air provided to the engine
第2题：
a leaking seal ring
heat transfer from exhaust valves
restricted cooling passages
overheated intake valves
第3题：
High firing pressures and low exhaust temperature in a diesel engine may resultfrom( ).
A.decreased piston to cylinder head clearance
B.increased exhaust system back pressure
C.early fuel injection timing
D.low scavenge air temperature
第4题：
passing the exhaust through long head pipes
diffusing exhaust vibrations through activated carbon baffles
increasing the exhaust gas velocity
reducing the exhaust gas velocity
第5题：
liquid in the cylinder
low compression in the cylinder
high exhaust temperature
poor fuel penetration
第6题：
During the valve overlap period, the exhaust pressure of a turbocharged four-stroke/cycle diesel engine must be less than the intake manifold pressure to ensure ______.
A.effective cylinder scavenging and cooling
B.constant pressure from the turbochargers
C.cooler operation of the exhaust system
D.effective constant pressure for turbocharger operation
第7题：
blows out the exhaust gases
supplies oxygen for combustion
cools the valves and cylinder walls
all of the above
第8题：
A two stroke diesel engine exhaust temperature will be lower than a four stroke diesel engine of the same displacement because the _____. ① MEP is lower and the scavenging air is cooling the exhaust gases ② valve overlap in a four stroke
A.①
B.②
C.① and ②
D.Neither ① nor ② is correct
第9题：
crankcase
piston
cylinder liner
crank cheek
第10题：
Leaking seal ring
Insufficient heat transfer from the exhaust valves
Block cooling water passages to the head
Excessive scavenging air provided to the engine