On an opposed-piston engine, which of the...

Question 1 / 270705eccefa2bacbc34ba4d47aa8

Question 1 of 270705eccefa2bacbc34ba4d47aa8

On an opposed-piston engine, which of the listed operating conditions will result from increasing the lower crank lead?

Question 1 of 27070

On an opposed-piston engine, which of the listed operating conditions will result from increasing the lower crank lead?

🔍 Key Concepts

• Opposed-piston two-stroke timing: relationship between upper and lower crank leads • Which ports each piston controls: exhaust vs. intake (scavenge/air) • Effect of advancing or retarding one crank on opening order and duration of ports

💭 Think About

• First, decide which piston (upper or lower) controls the exhaust ports and which controls the air intake ports on a typical opposed-piston engine diagram you’ve studied. • Think about what happens if you increase the crank lead of the lower crank: does that make the lower piston reach its port earlier or later in the cycle? • Once that piston moves earlier or later, how does this change both (1) which ports open first and (2) how long the air intake ports are uncovered during each cycle?

✅ Before You Answer

• Verify from your notes or diagrams: lower piston = which ports? exhaust or intake? • Mentally sketch a timing diagram: before and after increasing lower crank lead, and see which port opens first. • Check how changing which piston “leads” affects the time both ports are open together, which directly impacts intake duration.

Question 1 of 27070

On an opposed-piston engine, which of the listed operating conditions will result from increasing the lower crank lead?

Exhaust ports will uncover after the air intake ports

Duration of air intake will increase

Exhaust ports will uncover before the air intake ports

Duration of air intake will decrease

Question 1 / 270705eccefa2bacbc34ba4d47aa8

Question 1 of 270705eccefa2bacbc34ba4d47aa8

On an opposed-piston engine, which of the listed operating conditions will result from increasing the lower crank lead?

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Question 1 of 27070

On an opposed-piston engine, which of the listed operating conditions will result from increasing the lower crank lead?