FAA Powerplant Written Practice Test

What is one advantage of having a rough finish on cylinder walls?

1. Increased friction

2. Allows better ring seating

3. Prevents oil leaks

4. Reduces engine noise

The correct answer is: Allows better ring seating

A rough finish on cylinder walls plays a crucial role in engine performance, particularly in the context of piston rings. The primary advantage of this rough surface is that it allows for better ring seating. A rough texture increases the surface area for the rings to make contact, facilitating a more effective seal between the piston and the cylinder wall. This improved sealing is essential for maintaining compression and preventing blow-by, which is the escape of combustion gases past the rings. Additionally, the roughness aids in retaining a certain amount of oil, helping to create a lubricating film between the ring and the cylinder wall. This lubrication is vital for reducing wear and prolonging engine life. The interaction between the rough surface and the piston rings ensures that they adapt and conform more readily to imperfections, enhancing overall engine efficiency and performance.