pistons, differences??? Options

[ablose58]

Has anybody used those hypereutic pistons? are they any good and what pistons are the best for a 4 buildup? hypereutic or forged? thanks for the input. AL (IMG:style_emoticons/default/pray.gif)

[davep]

the hypereutic is a fancy word for cast.

Nonsense, the following is a direct quote from KB. Also "hypereutic" is a misspelling of the proper term. The alloy used and the means of fabrication are not always directly linked.

Aluminum silicon alloys used in pistons fall into three major categories: eutectic, hypoeutectic and hypereutectic. Probably the easiest way to describe these categories is to use the analogy of sugar added to a glass of iced tea. When sugar is added and stirred into the iced tea it dissolves and becomes inseparable from the iced tea. If sugar is continuously added, the tea actually becomes saturated with sugar and no matter how much you stir, the excess sugar will not mix in and simply falls to the bottom of the glass in crystal form.

Silicon additions to aluminum are very similar to the sugar addition to the iced tea. Silicon can be added and dissolved into aluminum so it, too, becomes inseparable from the aluminum. If these additions continue, the aluminum will eventually become saturated with silicon. Silicon added above this saturation point will precipitate out in the form of hard, primary silicon particles similar to the excess sugar in the iced tea.

This point of saturation in aluminum is known as the eutectic and occurs when the silicon level reaches 12%. Aluminum with silicon levels below 12% are known as hypoeutectic (the silicon is dissolved into the aluminum matrix). Aluminum with silicon levels above 12% are known as hypereutectic (aluminum with 16% silicon has 12% dissolved silicon and 4% shows up as primary silicon crystals).