I have seen people talk about hypereutectic pistons, but have never seen a clear discussion on what exactly hypereutectic means.

Also, how do you pronounce it - I can barely spell it, LOL.

 

HYPER-U-TEC-TIC

Hypereutectic is a metallurgical term referring to the the silicon content (relatively high) in the piston. It features a low expansion rate and is not as prone to scuffing as other alloys are.

 

Jason is correct, but be sure to know that "hypereutectic" does not just describe pistons, or just aluminum-silicon alloys. An alloy can be hypoeutectic, eutectic, or hypereutectic. Using the aluminum-silicon alloy as an example, a "hypo" would have very little silicon, a eutectic would have a balanced amount, and the "hyper" would describe a high content of silicon in the alloy.

Silicon reduces thermal expansion of aluminum. This allows manufacturers to produce pistons with higher tolerances and tighter fits. Silicon also greatly improves wear resistance. It also reduces heat transfer, which allows more heat to be retained in the cylinder. This allows for better emissions and performance in most cases.

The downfall is that aluminum-silicon is more brittle than a forged piston, and can't take as much pressure or abuse.

-Tony

 

It also means they are brittle as glass and break apart in the area of the ring lands when subjected to high boost or lots of nitrous! <img border="0" title="" alt="[Sad]" src="gr_sad.gif" />

 

yeah it means high silicon alloy aluminum for pistons.

Most cast pistons will only dissolve about 9.5% silicon, where as a Hyperutectic will be over 12% and most of them are 16% to above 20% Aluminum will only absord silicon Eutecticly to about 12% So HYPER means it's over that.

Kimchee, look what a regular eutectic piston looks like with boost or N2O much worse!

Bret

 

Thanks for the replies everyone, very informative.

 

just bought a 01 trans am auto 70000 miles stock, any good power mod tips

 

What the f*ck....

 

 

hahaha

 

So are the stock LS1 pistons are hypereutectic???

 

Roger that.

 

1. Get rid of your air filter...run pantyhose instead.
2. Tornados have proven a 15% increase in HP on the dyno.
3. Weight reduction. Here are the things you don't need on your car:

a. Interior carpeting
b. Exhaust - run open headers
c. Rear Brakes/ABS - the front brakes can do it all
d. Passenger and Rear Seats - tell them to ride with someone else.
e. Anything emissions related - kill the baby kittens!
f. Seat belts - seriously. Who wears them anymore?
g. Air bags
h. Bumper supports

Let us know how it comes out!

 

Good info, but I'm calling BS on the Tornado

 

does anybody really know if ls1s are hypers or is it speculation? I saw a piston out of a 5.3 that had melted very mush like a forged piston! usually when a hyper breaks it comes apart in chunks. The high silicon content doesn't like to melt. Like in the old LT1's the ring lans always broke and when they did the whole thing usually split off the top on the piston and when it came a part there where chunks of aluminum in the cylinder. The LS1 piston I saw clearly melted there was evidence of the piston material even melting itself to the combustion chamber. Just wanting some input on what people have seen, heard, or know?

 

That may be the best mod list I've ever seen.

 

They're cast. http://www.idavette.net/hib/ls1c.html

Jason

 

You pronounce it ... "Hyperpathetics".

 

Ahhh, Tony...

You have taken me back to my sophomore year of College where I took Introduciton to Materials Engineering. The Instructor wasa Graduate Teaching Assistant from France . I have never heard the word Eutectic pronounced any better.

 

Thanks! thats the info I've been looking for!!!