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2004 Forester XT
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21 Posts
Discussion Starter #1
I've got an '04 FXT that's completely stock in the drive train and exhaust. With 93K miles on the car, I'm wanting to plan ahead for turbo maintenance/replacement. Can I swap the stock FXT turbo with an STi stock turbo? If so, what should I look for and be aware of?

My thought is simply this, a stock STi turbo would be a good replacement (slight upgrade?) to consider for my daily driven XT about to turn 100K. Seems like there would be several folks on NASIOC who might have stock turbos to sell, so my hopes are to find a good, low mileage STi unit for a good price. I just can't swallow the idea of spending upwards of $1K or more to replace my current OEM turbo with an after market part (or dealer OEM piece) when my car is not tuned.

At the very most, after the turbo is addressed, I would consider a Cobb access port for some subtle tuning. The end result I'm looking for is to simply keep the car running, as trouble free as possible, for as long as I can without sinking a lot of money into it. That being said, I don't want to incur any unexpected additional costs with a turbo swap.
 

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2004 Forester XT
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21 Posts
Discussion Starter #4
I've read that sticky before and will go back and read more into all pages that follow the original post. Right off though, it doesn't really answer my question. Perhaps I should rephrase...

Will an STi stock turbo (04-05) serve as a direct drop-in replacement for the factory FXT turbo?

I understand I can easily upgrade my car with the few parts that "toddlamp" suggested to make my car an "STi", but I'm not looking to spend the money and time and make the full STi swap.

To let you know where I stand with my knowledge of our cars (cars in general, even), I only have the most basic understanding of how our engines work. I have no friggin' idea what a VF22, VF30, VF34 or a VF39 is outside of the general understanding that they are turbo chargers. Basically, I'm the original owner of my 04 FXT, drive it every day, pay the money to keep it running and just want to keep it going that way.

To the credit of your responses - which I do thank you for - if I were to source the STi turbo for my car, is it necessary to use the STi Intercooler, STi uppipe, and 04 STi ECU, too?
 

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2005 Forester XT
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100 Posts
I've read that sticky before and will go back and read more into all pages that follow the original post. Right off though, it doesn't really answer my question. Perhaps I should rephrase...

Will an STi stock turbo (04-05) serve as a direct drop-in replacement for the factory FXT turbo?

I understand I can easily upgrade my car with the few parts that "toddlamp" suggested to make my car an "STi", but I'm not looking to spend the money and time and make the full STi swap.

To let you know where I stand with my knowledge of our cars (cars in general, even), I only have the most basic understanding of how our engines work. I have no friggin' idea what a VF22, VF30, VF34 or a VF39 is outside of the general understanding that they are turbo chargers. Basically, I'm the original owner of my 04 FXT, drive it every day, pay the money to keep it running and just want to keep it going that way.

To the credit of your responses - which I do thank you for - if I were to source the STi turbo for my car, is it necessary to use the STi Intercooler, STi uppipe, and 04 STi ECU, too?
if you were to get the stock sti turbo (vf39) you would need the STI intercooler (could be a different one then the OEM STI one). The STI uppipe isn't a must, but having a catless uppipe does free up some extra ponies.

I'm not exactly sure whether or not the ECU is a must, but I have the Cobb AP and it's great. After putting in the turbo, you can have the AP tuned, and you'll notice a huge difference.


Hope this helps!
 

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Official sf.org decal guy
2006 FXT
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12,516 Posts
I've read that sticky before and will go back and read more into all pages that follow the original post. Right off though, it doesn't really answer my question. Perhaps I should rephrase...

Will an STi stock turbo (04-05) serve as a direct drop-in replacement for the factory FXT turbo?

I understand I can easily upgrade my car with the few parts that "toddlamp" suggested to make my car an "STi", but I'm not looking to spend the money and time and make the full STi swap.

To let you know where I stand with my knowledge of our cars (cars in general, even), I only have the most basic understanding of how our engines work. I have no friggin' idea what a VF22, VF30, VF34 or a VF39 is outside of the general understanding that they are turbo chargers. Basically, I'm the original owner of my 04 FXT, drive it every day, pay the money to keep it running and just want to keep it going that way.

To the credit of your responses - which I do thank you for - if I were to source the STi turbo for my car, is it necessary to use the STi Intercooler, STi uppipe, and 04 STi ECU, too?
Short answer is yes, however there is a HUGE 'but" after it.

Differerent turbos are going to flow differently at the same PSI level. There are others on the board that understand that much better than me though so it would be nice if they could chime in.

Regardless, because of the above you're still going to need some kind of tuning to get the turbo to perform correctly (read: safely). What is your ultimate goal? Modifications work in conjunction with other mods. It's best to have an ultimate goal, or at least an idea of where you want to end up. For example if you want to get a turbo now with the understanding that you are just looking for a slight power increase and that's it, your money would be better spent someplace else... namely with Cobb AccessPort. This will let you "tune' the car and give you added HP with no part install at all. This will also allow you to slowly piece together parts and tune accordingly as new parts are installed should you decide you want more power.

However, if you're eventually going to piece to get an STi setup, IMHO, it would be best to get all the parts needed and assemble them at one time.

I do not think that the stock ECU can compensate properly to accomodate a VF39 or VF48 (STi turbos).

Think about what you want to get out of the car. If you're not sure, a safe place to start in engine management.
 

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I think the op is just looking ahead should the turbo fail, and if a vf39 would be a direct replacement without any other mods. As far as I understand it should not be done without engine management. The sti ecu would be required.
 

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2006 Forester XT Limited 4EAT
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In answer to the original question, NO. Nothing other than a stock replacement will just drop in.
Our turbos can be had for around $200 in very good shape though.
If you are not going to do the work yourself, I'd say it'll be an absolute minimum of $2500 for required parts & labor for a safe STi swap.
 

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2004 Subaru FXT MT
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I think the op is just looking ahead should the turbo fail, and if a vf39 would be a direct replacement without any other mods. As far as I understand it should not be done without engine management. The sti ecu would be required.
Exactly. All of the VF series turbos will bolt right up. The only part that you would have to be prepared to replace as well is gaskets and the turbo inlet tube. Far to often during a turbo swap, these get buggered up. You better have a new one handy just in case.

Now, you would have to get tuned, whether its an OTS map on an AP or protuned. That isn't an option.

And frankly, while you are in there, it just plain makes sense to replace the uppipe with a catless one and get a performance downpipe. These aren't going to cost you much...tack on $300 to the budget buying used parts.
 

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2004 Forester XT
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Discussion Starter #10
Lots of good replies, guys. Keep them coming!

As fxt05 pointed out correctly, I'm planning ahead for when my current stock turbo will need to be replaced.

However, it's really good to hear everyone's thoughts on the STi turbo swap. This is helping me to plan what to do, based on the parts I may potentially find. If I do go with the STi swap, I'll need plenty of time to source good, used, dependable parts.

Another question: Can I only go with STi parts from the same model year? I thought I could use 04-05 parts, but want to be sure before I start finding parts from different years, thinking I can mix them.
 

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Official sf.org decal guy
2006 FXT
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12,516 Posts
Lots of good replies, guys. Keep them coming!

As fxt05 pointed out correctly, I'm planning ahead for when my current stock turbo will need to be replaced.

However, it's really good to hear everyone's thoughts on the STi turbo swap. This is helping me to plan what to do, based on the parts I may potentially find. If I do go with the STi swap, I'll need plenty of time to source good, used, dependable parts.

Another question: Can I only go with STi parts from the same model year? I thought I could use 04-05 parts, but want to be sure before I start finding parts from different years, thinking I can mix them.

If you're going for the TRUE 04xt ->STi setup then you can use any STi or 06-08 WRX/XT uppipe, a VF39, any STi intercooler, and an 04 STi ECU (this HAS to be from an 04).
 

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2004 Forester XT 4EAT
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Hello all, I am about to do an sti swap on my 04 FXT. My turbo is on it's way out.
I spoke to a Tuning shop in my area and from what he tells me the best/cheapest way to do this is to replace the turbo with STI Turbo, STI top feed injectors (06-07), STI intercooler, catless down pipe and flash or tune the existing ECU.
After I got off the phone with him I started researching turbos and found that there are so many options that came on the STI from 04 to 08. All seem to be a direct fit but I don't know which is the best option for me.
I want more power but really want reliability. Also $ is an issue. I want to do this for under 2 G's.
Any ideas on Turbos?
What about inter coolers? I found some on ebay for under $200.00 shipped.
Thanks Bob A
 

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4/07 wrx wagon/fozzy xt manual/auto
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for $2g's should be easy. vf/39/43/48 are all really interchangable and none really product more or earlier boost than the others, you should be able to find a used 1 locally for around $250 for a 39 with a crack to $550 for a newer 43/48.


have you read the sticky concerning this? its very in depth and a wealth of knowledge
 

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The Sub kit guy
2005 Forester X & XT VF39
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13,100 Posts
Hello all, I am about to do an sti swap on my 04 FXT. My turbo is on it's way out.
I spoke to a Tuning shop in my area and from what he tells me the best/cheapest way to do this is to replace the turbo with STI Turbo, STI top feed injectors (06-07), STI intercooler, catless down pipe and flash or tune the existing ECU.
After I got off the phone with him I started researching turbos and found that there are so many options that came on the STI from 04 to 08. All seem to be a direct fit but I don't know which is the best option for me.
I want more power but really want reliability. Also $ is an issue. I want to do this for under 2 G's.
Any ideas on Turbos?
What about inter coolers? I found some on ebay for under $200.00 shipped.
Thanks Bob A
If a shop said you need STi topfeed injectors, then they are idiots and I'd find a new shop to deal with.

Your 04 has 550cc sidefeed injectors, same as the 04-06 STi and they are plenty big for a VFxx swap. STi topfeed injectors started in 07 and are 565cc, and would require new fuel rails and all that. Not worth it for 15cc.

If your patient and shop around you can do the full swap and protune for under $2000. The economy has really brought prices down.

I did my swap over 2 years ago and parts, install and protune were under $2,000 total. That was for:
06 STi VF39 (port and polished)
06 STi TMIC
06 STi exhaust manifold and uppipe
Cobb catted downpipe
Cobb Accessport V1 (less than 1/2 the price of a V2)
Walbro Fuel Pump
Install and Protune at PRE in Portland Oregon.

For intercoolers, avoid the ebay junk. Stick with an 04-07 STi TMIC for the best fit and best bang for the buck. For turbos the VF39, VF43 and VF48 all came stock on USDM STi, and any one of them is a great option. They all put down similar numbers (VF48 is thought to hold boost a tad longer)and can be had for fairly cheap.

If you stay around 17psi or less, you will be under the 300whp/350wtq that seems to be the reliable limit of our transmissions.
 
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