Where would a Ni-Resist insert be located in an aluminum trunk piston?

The Ni-Resist insert is used in aluminum trunk pistons to provide enhanced wear resistance and thermal stability where wear conditions are most severe. Specifically, the upper ring belt is the location where the piston rings make contact with the cylinder wall during operation. This is a high-stress area due to the heat and friction generated within the engine, leading to significant wear over time. By placing the Ni-Resist insert in the upper ring belt, it helps to extend the life of the piston and maintain proper sealing, ultimately improving engine performance and efficiency.

The other regions of the piston, such as the lower ring belt or the pin boss, may not experience the same level of wear as the upper ring belt, making them less suitable for the insert. The crosshead piston design, which is typically used in larger applications, does not relate to the typical trunk piston where the insert is incorporated.