STI Pistons

[Swindog]

arent STI pistons only semi forged?

funky edit: split topic for discussion.

[Guest]

depending on model i believe, various info all over the net.

standard sti v1-2

forged sti v3-4

semi-forged diff comp ratio sti v5-6

standard sti v7-

no idea really im just playing keyboard warrior lot of paper research but someone knowledgeable can confirm

[Swindog]

Ah.

I thought they were all semi forged piston heads only. and non forged rods across all sti models.

[Guest]

sorry bud didnt mean to hijack probably more of a tech post but would be good to know ive spent hours sifting through sh*t on the net trying to work it out. ive dealt with the seller hes a good man been inside a lot of engines just thought he might clarify differences...

[funkytown]

 evowrx said:

sorry bud didnt mean to hijack probably more of a tech post but would be good to know ive spent hours sifting through sh*t on the net trying to work it out. ive dealt with the seller hes a good man been inside a lot of engines just thought he might clarify differences...

continue discussion topic split.

[Pappu1]

 evowrx said:

depending on model i believe, various info all over the net.

standard sti v1-2

forged sti v3-4

semi-forged diff comp ratio sti v5-6

standard sti v7-

no idea really im just playing keyboard warrior lot of paper research but someone knowledgeable can confirm

does standard meean cast pistons?

what exactly does semi forge mean - as in they started to forge it and then cast it while there or was cast and they glued on some forged bits ...

just curious as to what others think of it..

[funkytown]

well to talk about v7 sti pistons. they are hypereutectic. I still dont understand exactly what that means so i trolled a wiki link for everyone to read. I know it means they arent cast, but they arent exactly 'forged' either.

http://en.wikipedia.org/wiki/Hypereutectic_piston

afaik Hypereutectic pistons were only on v7 sti? but not 100%

[Guest]

i dont understand semi forged i have no idea its just what people say. some people say its impossible.

sta do semi forged which are cast and forged skirts or some sh*t i really have no idea.

there description as follows:

oe spec cast piston

anodized head, eutectic piston

semi forged, teflon skirts

chrome top rings

[Guest]

i was looking a sti pistons as cheap upgrade for engine when i pull down i over research everything someone who builds ej20s should pass judgement i can only speculate and subaru have no idea they work in a computer which doesnt say forged or non forged...

[chappell943]

Factory brochure states v3 sti has forged pistons

http://a15ff11300g.sakura.ne.jp/catalogue/GC.GFinpreza/96.8%20impreza%20WRX%20STI%20version3/96.8%20impreza%20WRX%20STI%20version3.html

other brochures here

http://a15ff11300g.sakura.ne.jp/catalogue/catalogue.html

[PhatRS]

AFAIK all are cast up till v7 just the STI got a better quality/stregth metal (you cant really semi forge something in my opinion, its either forged or its not......forging is a process afterall) , v7 are forged then the Hyperetetic (sp) cast were v8 onwards. Rods are all the same till v7+.

[pl0x]

From what I've read/heard:

V3/4/5/6 sti's only had the "semi" forged piston

V7 got "semi" forged pistons(but better than previous ones) and rods, better crank also

then V8 got hyperetetic cast pistons and a nitrate(d?) crank

 PhatRS said:

(you cant really semi forge something in my opinion, its either forged or its not......forging is a process afterall)

Agree

Semi forged are forged but not as strong? (not forged to the same degree maybe??)

[Dv8er - FSTWRX]

Wasn't the semi-forged thing covered a while back in another thread? Something about semi-solid forming.

Edit: Here we go.

http://www.clubsub.org.nz/forum/index.php/topic,18327.0.html

[B4 2000]

it all depends on the ratio of silicon in the alloy casting in making the pistons. the so called "semi-forged" has higher silicon rate than the normal cast pistons which allow it to take more abuse. Because the silicon has harder particles and lower expansion rate it has better wear resistance.

[WRXONP]

not discriminating and please dont take it the wrong way - but subaru owners are the only people i know of who get all emotional over forged pistons

realistically u can make 300 kw on stock cast pistons - because whats the most common failure in pistons ? broken ring lands - what causes it ? detonation

just sayin

[94 Leone]

that's why Our engine codes are EJ208DWAKE and the etcetera,

not RB20DET,

the det kinda shows the start of whats gonna happen...

just a bit of casual nissan hate.

buuuut, anyways.

If you want to make sure your pistons are forged, buy forged pistons, new.

if you don't really care, then it doesn't matter, does it?