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Extended Warranty Opinions

So are the crank, pistons, and rods forged in a stock STi?
 

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In the STi product training literaure, Subaru says:

High-strength, lightweight cast aluminum-alloy pistons
Forged high carbon steel connecting rods


It also says:

Hollow intake valves
Hollow camshafts
Shim-less valve lifters
Sodium-filled exhaust valves
Rear crankshaft journal utilizes a Metal Matrix Composite (MMC) insert
 

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I can't remember where I just saw the picture of the cast STi pistons; I think it was over at Nasioc in a thread where someone has pulled the STi engine completely apart. It showed the STi pistons had a webbing/hatching (i.e. cast) where as the internals they were putting in were smooth (forged.) Supposedly, it isn't a problem and should hold the same power. It was a fantastic thread, I wish I had saved the link.
 

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the STI pistons are Hyperutectic pistons, that means there is a vat of melted steel and in this vat they add a butt ton of silicon and mix it all up like a slushie and then they pour it into a mold and when it cools the melted magma steel soaks up a huge amount of silicon and discards the remaining silicon it cant accept, this property known as hyperutectics simply means that the pistons are extremely high heat resistant and can withstand more pressures than standard sand casted pistons, which in esscence puts them in the category of Forged pistons, they are kinda like the best of both worlds, daily driving and hard boost driving, but not as strong as forged pistons when putting more boost on em at a higher RPM

"SYLLABICATION: hy·per·eu·tec·tic
PRONUNCIATION: hpr-y-tktk
ADJECTIVE: Having the minor component present in a larger amount than in the eutectic composition of the same components."

in this case the minor component is silicon and the major is the actual metal its self


this is my wording and I am not a scientist so if you need some references to look at I can get them for you

Now as for making maximum power with these pistons, I have read many resources and acutally was told by a business here in san diego that does engine bulletproofing that the supra TT used hyperutectic pistons and those blocks have gone way over 700 HP in many cases, so therefore I am not saying that the block can or cant handle a huge amount of horsepower, I am saying that noone has broken the STI block or pistons or rods or crankshaft at any given amount so as for now we will have to give the car some time and people some balls until we start to see hard results.
 

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BoostdBoxer said:
the STI pistons are Hyperutectic pistons,
Do you have a reference for that?

that means there is a vat of melted steel and in this vat they add a butt ton of silicon and mix it all up like a slushie and then they pour it into a mold and when it cools the melted magma steel soaks up a huge amount of silicon and discards the remaining silicon it cant accept,
I'm pretty sure the pistons are aluminum, not steel.

"SYLLABICATION: hy·per·eu·tec·tic
PRONUNCIATION: hpr-y-tktk
It's more like "HIGH per you TEK tick".

Now as for making maximum power with these pistons, I have read many resources and acutally was told by a business here in san diego that does engine bulletproofing that the supra TT used hyperutectic pistons and those blocks have gone way over 700 HP in many cases, so therefore I am not saying that the block can or cant handle a huge amount of horsepower, I am saying that noone has broken the STI block or pistons or rods or crankshaft at any given amount so as for now we will have to give the car some time and people some balls until we start to see hard results.
The Supra block is cast iron. The STi's is aluminum. Even with hypereutectic pistons, I don't think the STi block will reliably produce huge amounts of power.
 

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The STi does have replacable piston sleeves as far as I know, and these should be able to be replaced with something stronger.....
 

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Slowride said:
BoostdBoxer said:
the STI pistons are Hyperutectic pistons,
Do you have a reference for that?

that means there is a vat of melted steel and in this vat they add a butt ton of silicon and mix it all up like a slushie and then they pour it into a mold and when it cools the melted magma steel soaks up a huge amount of silicon and discards the remaining silicon it cant accept,
I'm pretty sure the pistons are aluminum, not steel.

"SYLLABICATION: hy·per·eu·tec·tic
PRONUNCIATION: hpr-y-tktk
It's more like "HIGH per you TEK tick".

Now as for making maximum power with these pistons, I have read many resources and acutally was told by a business here in san diego that does engine bulletproofing that the supra TT used hyperutectic pistons and those blocks have gone way over 700 HP in many cases, so therefore I am not saying that the block can or cant handle a huge amount of horsepower, I am saying that noone has broken the STI block or pistons or rods or crankshaft at any given amount so as for now we will have to give the car some time and people some balls until we start to see hard results.
The Supra block is cast iron. The STi's is aluminum. Even with hypereutectic pistons, I don't think the STi block will reliably produce huge amounts of power.
Check out this thread... on Nasioc http://forums.nasioc.com/forums/showthread.php?s=&threadid=489989












Lots of other pics in that thread. I think you'll find all the information you are looking for.

IMHO SOA jipped the USDM STi by using cheaper materials. Obviously this is justified by the price target they were aiming for in this market. Something had to give. I am sure we would have paid closer to 40K if SOA went with forget pistons and all the other "High Performance" goodies. Now that's not to say that we didn't get a High Performance motor, I just don't think this motor will handle the same kind of power the JDM one can. And yes I know the JDM car makes less TQ/HP and uses a 2.0l motor. Again this is just my opinion and nothing else.
 
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