What advantage does aluminum have over cast iron when used for pistons?

Aluminum is chosen over cast iron for pistons primarily due to its superior heat transfer properties. This characteristic allows for better thermal management in engines, which can enhance performance by reducing the risk of overheating and improving engine efficiency.

In engines, pistons are subject to significant thermal cycling and must dissipate heat effectively to maintain optimal operating temperatures. Aluminum can absorb and transfer heat more quickly than cast iron, which ensures that the heat generated during combustion is managed properly, ultimately leading to more reliable engine operation and longer component life.

The lighter weight of aluminum, which is also a notable advantage, contributes to increased performance by reducing the overall mass of the engine components. However, the primary reason for using aluminum in this context is its ability to transfer heat more efficiently than cast iron.