MDE 1 Q1 Compression Stroke

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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?

D) It fluctuates

B) It remains the same

A) It decreases

C) It increases

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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

D) To reduce engine noise

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

A) To increase engine speed

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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?

B) Intake valve only

D) Both intake and exhaust valves are open

A) Both intake and exhaust valves

C) Exhaust valve only

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5. Timing of Fuel Injection

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

B) At the beginning of the compression stroke

A) During the intake stroke

D) During the exhaust stroke

C) At the end of the compression stroke

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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?

D) It fluctuates

B) It remains the same

A) It decreases

C) It increases

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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?

C) Exhaust valve only

D) Both intake and exhaust valves are open

A) Both intake and exhaust valves

B) Intake valve only

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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

A) During the intake stroke

B) At the beginning of the compression stroke

D) During the exhaust 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?

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

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

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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?

D) To draw fresh air into the cylinder

C) To compress the air in the cylinder

A) To expel exhaust gases from the cylinder

B) To ignite the air-fuel mixture

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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?

D) To draw fresh air into the cylinder

C) To compress the air in the cylinder

A) To expel exhaust gases from the cylinder

B) To ignite the air-fuel mixture

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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?

B) It reduces power output by increasing engine resistance

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

D) It has no effect on power output

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

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3. Piston Movement in Compression Stroke

Question: In which direction does the piston move during the compression stroke of a four-stroke marine diesel engine?

B) Upward toward the cylinder head

A) Downward away from the cylinder head

C) Remains stationary

D) Moves sideways within the cylinder

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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?

D) To reduce engine noise

B) To improve fuel atomization

A) To increase engine speed

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

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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?

B) Clogged air filters

D) Low coolant level

A) Faulty fuel injectors

C) Worn piston rings or cylinder liner

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