Cam-ground pistons are installed in some aircraft engines to which of the following?

Cam-ground pistons are installed in some aircraft engines to which of the following?

• A. Increase compression ratio
• B. Provide a better fit at operating temperatures
• C. Reduce piston weight
• D. Improve ring seal at cold start

Answer: (B)

Cam-ground pistons are machined so that the piston’s size and shape provide the right clearance in the bore when the engine reaches its normal operating temperature. Metals expand with heat, and the piston–bore clearance that matters most is the one that exists when everything is hot and under load. By aligning the piston dimensions for that hot condition, the rings can sit correctly against the cylinder walls, giving a tighter seal and reducing leakage and wear during operation. This is why the main benefit is a better fit at operating temperatures. It isn’t about raising compression ratio, reducing weight, or improving cold-start sealing—the key advantage is maintaining proper fit and sealing as the engine warms up.

Cam-ground pistons are machined so that the piston’s size and shape provide the right clearance in the bore when the engine reaches its normal operating temperature. Metals expand with heat, and the piston–bore clearance that matters most is the one that exists when everything is hot and under load. By aligning the piston dimensions for that hot condition, the rings can sit correctly against the cylinder walls, giving a tighter seal and reducing leakage and wear during operation. This is why the main benefit is a better fit at operating temperatures. It isn’t about raising compression ratio, reducing weight, or improving cold-start sealing—the key advantage is maintaining proper fit and sealing as the engine warms up.