Podcast
Questions and Answers
When does ignition of the fuel/air mixture occur in a four-stroke piston engine?
When does ignition of the fuel/air mixture occur in a four-stroke piston engine?
What is the typical timing for ignition in relation to Top Dead Center in a piston engine?
What is the typical timing for ignition in relation to Top Dead Center in a piston engine?
Which strokes involve the piston moving upwards in a piston engine?
Which strokes involve the piston moving upwards in a piston engine?
What does the term 'valve overlap' refer to in a four-stroke engine?
What does the term 'valve overlap' refer to in a four-stroke engine?
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At what point does valve lag occur in relation to the piston’s position?
At what point does valve lag occur in relation to the piston’s position?
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What is the correct sequence of operation for the four strokes of a piston engine?
What is the correct sequence of operation for the four strokes of a piston engine?
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What does the term 'valve lead' mean in the context of valve operation?
What does the term 'valve lead' mean in the context of valve operation?
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How does increasing the RPM of an aircraft’s piston engine affect ignition timing?
How does increasing the RPM of an aircraft’s piston engine affect ignition timing?
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What is the primary purpose of a cowl-flap in an engine?
What is the primary purpose of a cowl-flap in an engine?
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What role does 'alternate air' play in a fuel injection system?
What role does 'alternate air' play in a fuel injection system?
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Study Notes
Ignition Timing
- The combustion of the fuel-air mixture in a piston engine occurs during the compression stroke.
- The ignition timing is typically between 20° and 25° before the piston reaches Top Dead Center (TDC) during the compression stroke.
- The piston engine ignition timing is not affected by changes in RPM.
Piston Position and Strokes
- The piston is moving towards TDC during the compression and exhaust strokes.
- The piston is travelling upwards during the compression and exhaust strokes.
Valve Overlap and Valve Lag/Lead
- Valve overlap occurs between the exhaust and induction strokes.
- The correct sequence of four-stroke engine operation is: Induction, compression, power, exhaust.
- Valve overlap refers to the brief period where the inlet and exhaust valves are open simultaneously around TDC.
- Valve lag occurs when the inlet valve closes after the piston passes BDC.
- Valve lead occurs when the inlet valve opens before the piston reaches TDC.
Additional Applications
- Alternate air in a fuel injection system is air drawn from the engine cowling and directed to the induction system.
- Cowl flaps are used to control airflow over the engine cylinders, ensuring optimal operating temperatures.
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Description
Test your knowledge on ignition timing, piston position, and valve operations in four-stroke engines. This quiz covers crucial aspects of engine mechanics including timing, strokes, and valve functions. Perfect for automotive enthusiasts and students alike!
