I am getting ready to rebuild my 350 engine. I have a simple piston question for you all. What is the difference between HYPEREUTECTIC Pistons and FORGED Pistons? What are advantages that come with each?
Hypereutectic pistons are cast with a higher content of silicon that give them more strength than normal cast pistons. They are also harder and less prone to ring land pound-out and other detonation/preigntion damage. They have less thermal expansion and can be run quite tight (.001" piston-to-wall clearance).
Forged pistons are made with the aluminum forced under pressure into a mold. There are two main alloys, 2618 and VMS-75. 2618 is stronger but does not have any silicon so it does not have the scuff-resistance and has more thermal expansion that VMS-75. Thus, the 2618 is more suited to race only applictions while the VMS-75 is better suited to high-performance street, bracket-racing, etc. applications. 2618 pistons run more piston-to-wall clearance than do those made of VMS-75.
In your opinion, which piston is better? I am building a 350 for a 67' Camaro. I would like as much HP as possible but also the most torque i can get. I want to be able to drive it on the street and race it a little. I might even spray it with a little gas. I already have the top end of the motor. So i just need to build a strong bottom end.
If you do use KB pistons, be sure & read the instructions relating to ring gap & also the extra ring gap required for nitrous use. KB's need a wider gap than standard pistons because of the above mentioned proximity of the top ring to the top of the piston. Nitrous increases the needed gap even more.