Okay so can someone give me a simple idiot's version of WTH are Hypereutectic pistons? My friend is looking to pick up a Tib from a local seller on craigslist. We went last night to look at it and the guy said he has recently rebuilt the engine, put a new cam in, and hypereutectic pistons in it. I googled it and one thing stuck out to me, it said that these pistions are more brittle, is this true and if so im guessing that any major power increase like a turbo or nitrous would be a bad idea correct?

 

Hyperutectic pistons are cast.

 

Most hyperutectic pistons are cast, but some are forged. Hyperutectic means that there is more silicon in the aluminum alloy than can be dissolved properly, leaving amounts of free silicon that is not dissolved into the aluminum throughout the piston.

Simply saying a car has hyperutectic pistons doesn't tell you anything except for the silicon content is above the ratio that can fully dissolve into aluminum.

The main benefits of hyperutectic pistons are reduced wear and reduced expansion when heated. There is also less heat absorbed by the piston because it is insulated by the free silicon which has very different heat absorption and dissipation qualities than aluminum.