club.liberty.asn.au

Hi all, I own a 2004 Subaru Liberty GT Automatic (5eat) Sedan and have done the following mods:

-VF38/34 Hybrid turbo (VF38 housing with VF34 internals)
-Exhaust: Custom 3" downpipe and aftermarket mufflers (Stock middle pipes)
-AVO TMIC with silicone inlet
-AVO Cold air intake
-DW300c fuel pump
-GFB Respons blow off valve
-Prospeed silicone turbo inlet pipe
-Custom dyno tune

What power (kw) output can I expect with this setup on my car???
Also what other performance modifications can I do to the car?

***Will possibly also be installing an adjustable fuel pressure regulator or getting new injectors in the future if necessary.

Thanks everyone

If the vf38 rear housing is oem - then max of 180awkw

If rear housing has been machined, 190-195awkw max on 98 and 215-220 on e85

Thanks for your reply.
Fair enough.
I was expecting around the 200kw atw on 98.

Unfortunately I only made approx. 160kw atw...what could be the problem??

The tuner also said that the car didnt react to the tune as it should have. His recommendations were the following;
-Factory boost control solenoid is on max duty cycle and so I need to get a 3 port BS?
-The stock middle pipes are making the exhaust restrictive? (Thought a full turboback sounds bad and doesnt have much power in the twinscroll)
-Also suggested getting another wastegate actuator..atleast 1 bar?

Will any of those things fix the problem??
Didnt realise that the car would fall almost 40kw atw short of expectations...in that case there was no point changing the stock factory vf38 turbo.

Thanks

Definately get a 3-port.
Thats weird its so low. I was planning on going a very similar setup which the turbo builder, from previous builds, believed would get into the low 200's

Depends on the dyno, and you'd prob get a bit more from upgrading the whole exhaust.

How does it drive though? (More importantly)

Yea I was expecting that power level aswell.
Umm it still drives the same as before...just more laggy if anything compared to vf38
But honestly doesn't feel any faster...as that power level would suggest (160kw atw).
I dont know whats wrong.
I guess ill just try the things the tuner recommended.
Im making 18 psi boost tapering to 16psi.

Viv - i hope you dont mind but I'll respond here instead of pm as a future guide to anyone else

The 3 port solenoid will assist in holding / regulating boost, so a worthwhile investment.

I've never been a fan of these hybrid vf34/38 turbos. The main reason being the vf38 rear twin scroll housing is quite small and therefore restrictive. This is fine for the early spooling vf38 with the titanium wheel, but as any stock preface GT owner will tell you, they run out of efficiency very early. This is primarily due to the turbine housing size causing back pressure.

In saying that, I'm prepared to suggest its one or more of the following issues:

1. Pre turbo backpressure due to the small twin scroll housing on the vf38. This could be choking the vf34 wheel, creating more backpressure that limits ignition and valve timing advance.

2. Other tune parameters not being optimized (turbo dynamics, wg duty cycle etc). Whether in isolation or as a result of the above two issues (limitation of 2 port and turbo back pressure), it will limit your ability to spool and rev.

It is very unlikely that your mid pipe is the issue, as your back pressure limitation will be in the turbine housing first, before the mid pipe. If you were talking about a larger turbo / turbine housing with lower backpressure, then the mid pipe may become a restriction at that point. It's the same as having a 2 inch hose on the end of a straw and saying if you went to a 3 inch pipe instead of 2 inch, that it would help your straw breathe better. The straw is still the bottleneck, and the vf38 rear housing is analogous to the straw in this example.

The fact that its alot laggier without the top end that you should have with the vf34 tells me its restricted.

Take some logs and post them up here for further discussion. Happy to help out if need be.

Thanks heaps for your comprehensive reply dr20t!
Yea man no worries...please do. The point of this is for everyone to learn collectively!

Its gonna suck to have to go through the hassle of taking out the turbo to check it out??
What turbo should I get if I were to return this in the worst case scenario??
Also what 3 port should I get? Cobb, Grimmspeed etc?
Where can I get middle pipes to complete my exhaust for cheap?

Thanks

See if you can buy the twin scroll housing off the kinugawa td04-hla19t on its own. Try that first and if you cannot, then next best option would be to buy a set of kando / psr twin scroll headers and uppipe, get yourself a kinugawa td05 18g turbo with the SLS billet wheel and spec c twin scroll housing.

Sell your vf34 sans vf38 housing and try and make up some cash

Before you do that - Post a log of your car here with the following parameters

Engine load
Engine speed
Inlet avcs angle (left and right)
Exhaust avcs angle (left and right)
Total timing
Feedback knock correction
Fine learning knock correction
IAM
Manifold relative pressure
Mass airflow (g/ second)
Wideband afr

Fair enough man...thanks.

Btw how can I get all that information??
I don't have any logging tools or software...

Hopefully one of the Sydney members can help you with this......

Viv wrote:Fair enough man...thanks.

Btw how can I get all that information??
I don't have any logging tools or software...

Where abouts in Sydney are you?

I can log it if you're in south west

Good read so far. Kinda happy I didn't end up getting the vf37/38 turbo made up if this is all it'll really give. Any idea how the vf38 housing compares to the vf45 one? With more boost chucked at the stock vf45 (18-19psi) EGBP never gets past about 25psi which I would have thought is fairly reasonable.

dr20t wrote:

Viv wrote:Fair enough man...thanks.

Btw how can I get all that information??
I don't have any logging tools or software...

Where abouts in Sydney are you?

I can log it if you're in south west

andy_mac: Nah man its not like that...generally its a great thing! vf38/34 hybrid turbo!
Theres just something wrong with my specific application unfortunately.

dr20t: Im located close to Liverpool, 2170. That would be great if you could help me out please.

Thanks heaps

Viv
That power level is about right for an auto with your set up and a non happy dyno.
I got the same power level on 98 with similar mods with turbo being a td04hla-20t which probably flows similar to your 38/34 hybrid.

dr20t the numbers you are quoting for stock vf38 power potential on 98 would be for manuals, correct? Viv has an auto.
On e85, my current turbo has more potential (flows more) than a stock vf38 and I can't see any logical explanation with my current 180kwatw why I am down 35kwatw (215 kw max less 180 kw)