john banks

Piston type - forged or hypereutectic is debated with various sources giving conflicing info. Subaru marketing material says one thing, appearance of pistons says another for some models. And then others say the only way to analyse them is by sampling the alloy not from appearance - ie forged could have appearance of cast! Some are saying that every version 8 onwards whether 2.0 or 2.5 is hypereutectic. Some say the hypereutectic pistons are not as strong, some say otherwise. Some say there is a high risk of forged nipping the bores because they expand and are quite tight, others say the same for hypereutectic because of the tighter clearance despite the lower coefficient of thermal expansion.

Whatever, there are not large numbers of 400 BHP STI engines of any vintage blowing up so reliability and strength are impossible to prove either way.

I've got beyond worrying about it as hypereutectic pistons are used in 4G63s and Supra engines without worry at higher outputs per cylinder than most of us are considering.

[Edited by john banks - 12/2/2003 12:22:00 PM]

whiteyisback

Just wanted to know what a new Spec C, fully decatted and remapped would chuck out ? near the 400 bhp mark ? Would love to know if any of the tunning companies (Scoobysport, Xtreme, Pat, BRD, TSL, anyone) have done this sort of work to one yet and what they managed to achieve. I'm only curious as I'm considering selling my WRX and getting one or an EVO 8 FQ330.

cheers guys.

CustomScoobyIOM

Well apparantly with a full decat a magazine said you can have 350bhp easy.

So with the map I wouldnt see why not.... Very close.

greasemonkey

Very much doubt it. Internals might be up to it, but suspect that reliable 400 on UK pump fuel would require change of turbo, injectors and intercooler at the very least.

Still, this is guesswork. Bob's been playing with one so he's the man to ask.

Nathan L

350-360 should be realistic.

A larger turbo would probably be needed to hit 400.

Nathan..

Bob Rawle

It will need more than the decat to get there (400), FMIC, injectors, f-pump, f regulator, induction, exhaust, turbo.

These cars are NOT 320 bhp as std, they are pretty much normal 280/290 terrirory.

My car is estimated at doing around 340 ish using AP22 with std exhaust and induction, just a remap, must get to PE to benchmark so I can change the exhaust and filter and see what this twin scroll is made off.

My personal target is to break 400 bhp with the std engine, its certainly strong enough imho and the steps along the way are being benchmarked for reference.

bob

Sti_Lad

Are the internals of the Spec C engine that different to a sta8 Sti8 Bob? Or is the Spec C just a Sti8 lump with equals and twin scroll???

Nathan L

The internals from a UK STi8 are different to those from the JDM STi9. JDM version has Nitrid crank etc.

However the only difference i'm aware of, between a JDM STi9 and a Spec C is that the Spec C has a roller bearing turbo, whereas the STi has a sleeve bearing variety.

Nathan..

The Fixer

Eurospec Sti 8 and JDM STi 8 are different as the JDM STi8 has the STi 9 engine in it.

P20SPD

iTrader: (1)

Have i read correctly there. Bob, do you have a Spec C now? Have you still got the Sti5?

Steven

CustomScoobyIOM

I stand corrected sorry mate!

Nathan L

Steve

In the absence of Bob he now has a JDM STi 9 GL as well as the STi5

The 9 is bloody quick too

Nathan..

P20SPD

iTrader: (1)

Jolly Green Monster

iTrader: (4)

Steven,

Can confirm that too as two friends took a car along for a remap by Bob, one of whom wants to buy a Spec C so was drawling all over the STi9.. apparently..



Simon

Bob Rawle

Thanks guys, yes I do have an Sti9 GL as well as the STi5 at the moment, the '5 has just had the centre diff replaced and is "fighting fit" again.

The GL is the same as the spec C except for the turbo being sleeve bearing (as Nathan says) and the fact it has trim, apart from that its pretty much got all the goodies except the boot mounted water tank (fitted that as an extra).

Engine is dramatically different to the Sti8 which is the UK car, that is still the same as the STi 7, the '9 has different crank, rods, pistons, cams, fuel system and so on.

A VERY quick car after remap .. still std exhaust and induction though soon to be changed. I am currently running 1.5 bar mid range taper to 1.2, needs an uprated actuator to get more boost at the top, which will be done with the exhaust etc.

bob

hypoluxa

John,

Regarding pistons, hypereutectic pistons are just cast pistons which have a high silicon content (which adds hardness). A forged piston will be stronger.

john banks

"This latest STi piston is a departure from previous years in that it is a cast aluminum design. However, we believe this to be a special hypereutectic material and STi claims a 120% increase in strength over their previous forged pistons. The high silicon content of the aluminum also has the benefit of providing exceptional scuff resistance and reduced thermal expansion which allows for the use of tighter clearances."

No one seems to agree on this!

Danny B

Bob,
How is the "tinkering" with the STi9 coming along? Any RR results yet?

Cheers

bartmanuk

if the spec c is only 280/290bhp then wots this all about in the october issue of evo mag??? spec on spec-c
im not trying to disagree with anybody,just curious myself.

BM

Danny B

Because that Spec C wasn't standard,ie- different exhaust and ECU remapped.

AJbaseBloke

We've got a buddy with a non-spec C car running the std sleeve bearing turbo, sub computer, full exhaust w/sport cat, BOV and a std style replacement filter pushing 356ps on 100RON (it was 32deg when tested too, so more now it's cooler!). Torque is in the region of 45kg/m too!! Not sure if the Bosch rollers we were on are the most accurate about (although they seem to be pretty accurate - his car got 286ps when std). We were shocked with the number, even the tuner made them run the thing 3 more times to make sure...all were within 6ps (after making sure the IC etc was nice and cool to prevent damage of course). Oh, and the AFRs were rock solid and very safe too

In short, the thing is scary fast!!

Will spin wheels when going for it in 2nd. Chirp on the 3rd shift too (running 070s and dry).

bartmanuk

cheers danny,i feel a bit gutted now...LOL

i thought we had a subaru supercar.

BM