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What does "hypereutectic " mean???

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Old 11-05-2002, 11:03 PM
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Default What does "hypereutectic " mean???

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.
Old 11-05-2002, 11:23 PM
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Default Re: What does "hypereutectic " mean???

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.
Old 11-05-2002, 11:35 PM
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Default Re: What does "hypereutectic " mean???

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
Old 11-05-2002, 11:35 PM
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Default Re: What does "hypereutectic " mean???

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" />
Old 11-06-2002, 12:07 AM
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Default Re: What does "hypereutectic " mean???

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
Old 11-06-2002, 10:44 PM
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Default Re: What does "hypereutectic " mean???

Thanks for the replies everyone, very informative.
Old 12-14-2005, 10:23 PM
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just bought a 01 trans am auto 70000 miles stock, any good power mod tips
Old 12-14-2005, 11:20 PM
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What the f*ck....
Old 12-14-2005, 11:55 PM
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Originally Posted by Ferocity02
What the f*ck....
Old 12-15-2005, 01:02 AM
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hahaha
Old 12-15-2005, 01:06 AM
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So are the stock LS1 pistons are hypereutectic???
Old 12-15-2005, 01:08 AM
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Originally Posted by BIZZARO
So are the stock LS1 pistons are hypereutectic???
Roger that.
Old 12-15-2005, 08:48 AM
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Originally Posted by foo7887
just bought a 01 trans am auto 70000 miles stock, any good power mod tips
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!
Old 12-15-2005, 09:06 AM
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Originally Posted by MeentSS02
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
Old 12-15-2005, 09:25 AM
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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?
Old 12-15-2005, 10:11 AM
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Originally Posted by MeentSS02
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!
That may be the best mod list I've ever seen.
Old 12-15-2005, 10:43 AM
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Originally Posted by MPFD
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?
They're cast. http://www.idavette.net/hib/ls1c.html

Jason
Old 12-15-2005, 10:54 AM
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You pronounce it ... "Hyperpathetics".
Old 12-15-2005, 11:18 AM
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Originally Posted by Nine Ball
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
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.
Old 12-15-2005, 12:21 PM
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Thanks! thats the info I've been looking for!!!


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