MDE 1 Q1 Compression Stroke

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7. Role of the Compression Stroke in Power Output

Question: How does the compression stroke affect the power output of a marine diesel engine?

A) It directly increases the power output by compressing the fuel

B) It reduces power output by increasing engine resistance

D) It has no effect on power output

C) It prepares the air for combustion, indirectly contributing to power output

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4. Effect on Air Temperature During Compression Stroke

Question: What happens to the temperature of the air inside the cylinder during the compression stroke in a marine diesel engine?

C) It increases

B) It remains the same

D) It fluctuates

A) It decreases

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5. Timing of Fuel Injection

Question: When is fuel typically injected into the cylinder of a marine diesel engine?

A) During the intake stroke

C) At the end of the compression stroke

B) At the beginning of the compression stroke

D) During the exhaust stroke

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5. Timing of Fuel Injection

Question: When is fuel typically injected into the cylinder of a marine diesel engine?

C) At the end of the compression stroke

D) During the exhaust stroke

A) During the intake stroke

B) At the beginning of the compression stroke

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6. Compression Ratio in Diesel Engines

Question: Why is the compression ratio typically higher in diesel engines compared to gasoline engines?

B) To improve fuel atomization

C) To ensure the air is hot enough to ignite the fuel

D) To reduce engine noise

A) To increase engine speed

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7. Role of the Compression Stroke in Power Output

Question: How does the compression stroke affect the power output of a marine diesel engine?

A) It directly increases the power output by compressing the fuel

B) It reduces power output by increasing engine resistance

C) It prepares the air for combustion, indirectly contributing to power output

D) It has no effect on power output

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2. Valve Operation During Compression Stroke

Question: During the compression stroke of a four-stroke marine diesel engine, which valves are closed?

D) Both intake and exhaust valves are open

C) Exhaust valve only

A) Both intake and exhaust valves

B) Intake valve only

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1. Purpose of the Compression Stroke

Question: What is the primary purpose of the compression stroke in a four-stroke marine diesel engine?

A) To expel exhaust gases from the cylinder

B) To ignite the air-fuel mixture

D) To draw fresh air into the cylinder

C) To compress the air in the cylinder

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8. Common Issues During Compression Stroke

Question: What could be a possible cause of reduced compression in a marine diesel engine?

A) Faulty fuel injectors

B) Clogged air filters

C) Worn piston rings or cylinder liner

D) Low coolant level

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