Question 378Motor Plants - Assistant Engineer

70% to pass

The average exhaust temperature of a two-stroke cycle diesel engine with a turbine- driven supercharger is lower than a similar four-stroke cycle diesel engine at equal loads because_______________.

Atwo-stroke cycle diesel engines have a higher M.E.P. than four-stroke cycle diesel engines
Bfour-stroke cycle diesel engine exhaust is cooled by scavenging air
Ctwo-stroke cycle diesel engines have a lower M.E.P. than four-stroke cycle diesel engines
Dthe opening of the two-stroke cycle diesel exhaust ports or valves occurs much later than in four-stroke cycle diesel engines
AI Explanation

The correct answer is C) two-stroke cycle diesel engines have a lower M.E.P. (mean effective pressure) than four-stroke cycle diesel engines. The reason for this is that two-stroke cycle diesel engines have a lower M.E.P. compared to four-stroke cycle diesel engines, which results in a lower exhaust temperature. This is because the two-stroke cycle engine has a shorter power stroke and a higher proportion of the cycle is devoted to intake and exhaust, leading to a lower M.E.P. The other options are incorrect because: A) and C) are contradictory statements, and B) the scavenging air in four-stroke engines would actually lead to a higher exhaust temperature, not a lower one.

Want to practice with timed exams?

Download Coast Guard Exams for the full exam experience.

Get the App