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)

[machina]

you always want to go with a forged piston if you have the $$$.

the hypereutic is a fancy word for cast. Most think the Keith Black are the best cast piston if you don't want or need forged pistons.

dr

[lmcchesney]

The benifit will depend on your combination. KB pistons also utilize a different dynamic compression ratio with their pistons. It sounds like the squishy tech that John of Massive spoke of, but I have not heard back from KB tech as yet. Not to get Jake started but here is the tech site: http://kb-silvolite.com/article.php
L. McC

[Jake Raby]

KB uses a different method of ring land design for SEALING THEIR RINGS. The Squishie piston is entirely different than a KB, due to the dome shape and design on the crown of the piston. This enhances the quench in the combustion chamber.

KB pistons are great for daily drivers and spirited performance engines. They are better for street use than any forged piston. they burn less oil and rattle less when the engine first starts. They do require a minimum skirt clearance or .0018 and most of the kits available have too tight of clearances out of the box. thats why we bore and hone our own cylinders.

[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).

[Jake Raby]

I have used over 200 sets of the KBs and had 4 failures.. ALL THESE FAILURES were cylinder related and a result of inaccurate skirt clearance from the manufacturer of the cylinders...
Thats when I went to only using bored OEM cylinders set to my tolerance.

KBs are very strong pistons and do not have the issues related with "cast" pistons.

[Dave_Darling]

Forged, IMHO, are only worth it if you are boosting or if you are really pushing the ragged edge of performance. They're bloody strong, but bloody expensive. And they expand quite a lot, so they will "slap" when cold.

Hypereutectic cast pistons (you can get cast pistons that are not made from a hypereutectic alloy as well, they're usually cheaper) expand at a rate closer to the cylinder expansion. So they can be set up with less clearance when cold, and they pretty much won't slap. They're plenty strong enough for all you can throw at them with just about any 914/Type IV motor, IMHO.

--DD