Discuss what year 302's had forged pistons? on AllFordMustangs.com, the place for Mustang enthusiasts.
Welcome to our Mustang forums where Mustangers come together to hang out, discuss and enjoy their favorite Mustang hobby with fellow Mustang enthusiasts. We invite everyone to read, post, and enjoy our Mustang forum as well as the many other sections of our site.
You are currently viewing our forums as a guest. By joining our community you gain access to post topics, communicate with members, upload your photos and access many other special features. Registration is fast, simple and free so why wait, join our Mustang community today! If you have any problems with registration or your account login, please contact support.
There are two types of OEM pistons: cast aluminum and forged aluminum. The "cast" or "forged" just refers to how the piston is formed, i.e. one is cast into a mold and one is forged (forced) into a mold.
Cast means molten aluminum is poured into a mold.
Forged means a chunk of aluminum is forced into shape by a (massive) press.
Late '92 (model year) and up pistons are cast hypereutectic aluminum.
Originally posted by GreyLX306 at The Corral: The term "hypereutectic" means that the mixture of silicon in the aluminum exceeds the eutectic point. The eutectic point is the exact mixture (12.6% silicon in aluminum) where solidification of occurs completely at the eutectic temperature (around 550 degrees celcius in Al Si), and in turn forms a lamellar structure with optimum dispersion strengthening. With more than 12.6% silicon, the silicon begins to solidify as the alloy cools, but before the eutectic temperature is reached, thus leaving patches of pure silicon despersed throughout the alloy.