Gen IV (pre-FL) GT detail confirmation

[Sean82]

Hi all, I'm trying to confirm a few things about the 04-06 GT as I'm looking to buy one to replace my Forester.

am I right in the following:

1. 2.0L twin scroll (is there a "designator" for the donk? Such as EJ255 for the post-FL, WRX and Foz XTs?)
2. 5EAT gets VF38 (which is pretty small) while the 5MT gets the TD04-HLA (which is actually quite large, despite all other TD04s being basically minuscule)
3. ~180+ atwkW is is going to be pretty difficult with either turbo without great supporting mods
4. Down pipe upgrades are limited because of the twin scroll thing, and even more so if I get 5EAT (probably going to avoid given troubles getting DP to fit the 5EAT in my Foz)
5. Injectors are side-feed

Thanks for reading
Sean..

[dr20t]

Hi all, I'm trying to confirm a few things about the 04-06 GT as I'm looking to buy one to replace my Forester.

am I right in the following:

1. 2.0L twin scroll (is there a "designator" for the donk? Such as EJ255 for the post-FL, WRX and Foz XTs?)
2. 5EAT gets VF38 (which is pretty small) while the 5MT gets the TD04-HLA (which is actually quite large, despite all other TD04s being basically minuscule)
3. ~180+ atwkW is is going to be pretty difficult with either turbo without great supporting mods
4. Down pipe upgrades are limited because of the twin scroll thing, and even more so if I get 5EAT (probably going to avoid given troubles getting DP to fit the 5EAT in my Foz)
5. Injectors are side-feed

Thanks for reading
Sean..

1. Yes. Manual was ej20x. Auto ej20y. Quad avcs motor. Z20 heads which have slightly larger ports than the d25 heads on the ej257 (2.5 turbo in wrx Sti ). These engines were jdm (2003-2008 legacy gt) or audm (prefacelift 03-06 liberty gt) only. The ecu to run these engines is unique and worth a fair whack of money compared to other Subaru ecu's.

The heads flow pretty well. I'd say fourth in line for the EJ/EZ series motors (jdm ej207 version 10 w20 heads being first, v7-9 ej207 s20 heads being second, ez30 heads next and then the z20 heads). The quad avcs design was the first used by subaru, and thus alot of these learnings went into the jdm wrx Sti ej207 in 2008 onwards grb quad avcs motor.

The engine runs 9.5:1 static compression with a flat piston surface to deck height , has an open deck block, forged rods, semi forged (crown top) pistons, and a forged single-cross-drilled crank.

2. Both turbos are very similar in size. No real difference other than cartridge designation. No known compressor maps for the vf38 but full boost and peak torque by 2400rpm tells you something about the effectiveness of the twin scroll and titanium blade, as well as how small the turbo is.

3. I would say a true 180kw atw would be impossible on either turbo unless running e85 and a shitload of timing which the motor won't like for long.

4. Correct.

5. Yes indeed

Hope this helps

Mick

[Sean82]

Thanks Mick

Would a TD-0518G be too much for a high mileage (150,000+) engine to handle if it's unopened? (Again, I know this is all theoretical and depends on more factors than there are dickhead drivers, and there are a LOT of those, but just thinking out loud... I know what ~180atwkW feels like and it's where I'd like my new car to be)

[dr20t]

TD05-18g would be perfect in my opinion

But it will be a little laggy compared to a 2.5. However a good tuner who is familiar with the dual avcs heads will get this singing. I'd say 200atw would be possible on 18-19psi

Mick

[Sean82]

Brilliant, thanks again Mick.

Lag, that's fixed with this:

[Robbks]

TD05-18G is good on a 2L
on an old EJ20G in a GT leggy we were seeing 17PSI by 3200rpm in 3rd/4th and pulling all the way to redline.
with higher compression and AVCS it should be an even better streetable unit.
And that pulled a genuine 170ATW just with a Jap WRX ECU

The GT and a good tune should do 180 fine on 98RON

[Sean82]

Probably should mention if things go as I'm planning, I'll be retaining the twin scroll headers.
This should help over come some of the lag issues, right?

[Robbks]

You can buy the GT Pumps GTPSO2 with an 18G option in their Twin Scroll model too.

http://www.gtpumps.com.au/subaruturbos.html

Kinugawa do one too
with billet wheel option
http://shopping.kinugawaturbo.com/kinug ... 3-2-1.aspx

[Sean82]

You can buy the GT Pumps GTPSO2 with an 18G option in their Twin Scroll model too.

http://www.gtpumps.com.au/subaruturbos.html

I know...seeing that makes me all warm and fuzzy inside

I was considering a twin scroll conversion on my Foz, but now it's going (medical reasons) hence the intrigue into Gen IV LGT

[dr20t]

Twin scroll turbos that you're talking about will not work with your up pipe or headers

The only twin scroll turbos that will fit your manifold and uppipe as is are;

Vf38
Td04hla
Vf44
Vf45

That's it. No other aftermarket or factory twin scroll turbos will work as the twin scroll flange is unique on the liberty / jdm legacy GT twin scroll.

The solution is to get a set of jdm ej207 v8-10 headers and then you can use any aftermarket twin scroll Subaru flanged turbo (like the GT pumps one Rob mentioned above) or the factory jdm wrx Sti twin scroll turbos such as ihi vf36/37/42/49/53/55/56

*edit* - or you can buy aftermarket twin scroll equal length headers and again run any of those turbos I listed as they are based on the jdm wrx Sti twin scroll flange not the legacy/liberty twin scroll

Mick