Subaru EJ20T Turbo on an EJ25D

[RNandKT]

I have read a lot of the posts on swapping in a WRX or even an STI motor into my GT, but the wiring mess that is involved, along with the cost of finding one in decent shape seems like more of a nightmare then a dream.

I was wondering if anyone wanted to do a write up on putting a WRX stock turbo on a EJ25D. These can be found really cheap (a place out of Cali sells for $250 each) using an intercooler from a WRX or an STI, and paying for a fabbed up exh manifold. Then using the Software on a laptop hooked up to manage it then having it professionally tuned.

I realize many people have been flamed about having to stick to around 6-7 psi. But as on AVO's web site this can easily make 220 to 260 hp when tuned correctly and thats more than the WRX stock. (and frankly more than plenty for me). I love my legacy and would like to just have a little more and this seems to be a better way to go for the mild builder.

Turbo - $250
Intercooler - around $300 - $500
Ex madifold tips to have welded - $150 pair
Software managment - $700
Plus some to have the exh shop do some tube bending and assorted things such as tapping an oil line, etc.

Seems to me this could be kept under $2000 easily. Now I don't have the experience to complete it. But I would love to hear from those who do and or have.

[Lemanschamp]

I've spoken with a long-time subaru master tech and he said that a couple years back someone asked him to do this, and he ended up using donor parts from a Forrester XT, i.e. crossmember and exhaust setup. He said it works really well, if your willing to do the work for the wiring and all that. But he said it was worth it.

[sheepdog]

it's definitely possible, there was a guy on here with a fwd legacy and a wrx turbo, etc. However, most people opt to wait and spend the extra $1k, and get a wrx motor, where you'll have more options later, and less reliability issues. IIRC, there is very little wiring involved, but you have to tap the oil pan for an oil line to the turbo and other stuff.

[ivwarrior]

I wouldn't be suprised if it's cheaper and easier in the long run to just do a swap. On top of the stuff you mentioned, I'm sure you'll have some issues with sensors and wiring, as well. Factor in the time to sort everything out, and the questional reliability and it just doesn't seem worth it.

[xcntrk75]

On the nasioc forums, you can pick up used TD04's for <$100 bucks and stock tmic's for the same... Just pointing out those prices you have posted are very high!

{edit} I have a stock WRX TMIC for sale! All the piping, hosing, etc. $100 shipped... ;)

[RNandKT]

TD04 is that the stock turbo from a WRX? Some of these numbers are new to me as most of my engine experience doesn't include turbo's.

So if they can be had so cheap why are so many people suggesting to swap instead? The only reason I can see is because the WRX and STi engines have more potential for future mods.

But what about all those people out there who just want their Legacy's to be as fast as a WRX instead of buying one?

Come on someone must have a write up somewhere on doing the "BUDGET" turbo?

Oh and I might be interested in that Intercooler. (question what does TMIC stand for? I assume IC is intercooler but what is TM?)

[Huffer]

TMIC - Top Mount InterCooler

[Perdue]

They even make uppipes and downpipes to run from your stock manifold to the WRX turbo, locating it close to the stock location. The name escapes me though.

You'll have to figure something out for boost control though. IIRC, the internal wastegate on the TD04 opens at 11psi, which is way too much for the NA motors. This can be solved my modifying a 5psi wastegate actuator from an older subaru turbo onto the TD04. Another option is to go external wastegate, which will cost a little more. Some people from RS25 are using the generic ebay 38mm wastegates and modifying the uppipe to accomadate the wastegate. This can be dumped into the atmosphere, or into the dump pipe (I think...someone correct me if I'm wrong). Some people weld the stock TD04 wastegate shut from there, but you should be able to leave it alone with no problems.

Once that's done, add a boost controller, intercooler and piping, some sort of BOV (would be better to be recirculating if your car is MAF based), an intake, and most importantly, good engine management.

This was originally my plan with my legacy. I had planned to run 5-6psi on the stock block, and later get a set of DOHC EJ25 heads and a STi shortblock, mate them together, then crank the boost up. That all fell through though. :roll:

[jey]

+1 on buying a WRX crossmember and running a stock WRX turbo exhaust manifold. I was able to acquire a lightly used TD04 turbo AND intercooler AND BOV AND exhaust manifold AND upipe AND midpipe AND muffler for $150. Budget turbo kit indeed! The crossmember from the dealer is under $200.

But yeah, if you're going to be running a turbo on your high-compression NA engine, spend the bucks on engine management and getting it tuned properly, or something will break. Definitely can be done for less than $2000 :)

[xcntrk75]

So if they can be had so cheap why are so many people suggesting to swap instead? The only reason I can see is because the WRX and STi engines have more potential for future mods.
Because the EJ25D motor and heads aren’t designed for the significant positive pressure of forced-induction systems. Yeah you can run a fabricated turbo setup and push the motor to achieve WRX levels of power. Of course the same can be said for the EJ20-wrx motor which can be pushed to achieve STi levels of power…leading up to the EJ25-sti motor which can be pushed upwards of 400+whp. All of which increases performance, but reduces reliability and longevity.

[sheepdog]

Don't get me wrong, it can most definitely be done. I, however, am all about reliability, and I just get queasy thinking about pushing the limits of that motor all day long. I know a couple of people with 2.5RSs that did this, blew up the motor, and then ended up spending another 3k in the end to swap it.

Not to mention your options for mods increase exponentially. Look at xcntrks car lol.

[RNandKT]

These are all great opinions, and a lot of scattered tid bits of info. But can someone do a full write up including where they got parts from recommeded part alternatives. Instructions including how to tap the oil line, how to modify the turbo's wastegate to limit it to 5 psi. How to set up the engine management etc etc.

Also how do the BOV's (blow off valve right) work?

Thanks for all the comments

[ten80]

I don't mean to sound harsh, but it would take someone hours to create a detailed write-up for your rather broad-topic questions. The answers also depend on your setup, personal preference, and power needs/desires.

I know for certain that I have seen the answer to every single on either on this forum or on Nasioc.com. Part of the problem is that there are many different options for part sources (ebay, classifieds, junkyard, dealership, craigslist), and many different ECM's (Hydra, Autronics, megasquirt, PP6, ecutec, Accessport) for different tuning/swap needs, in addition to several ways of limiting boost to 5psi. Doing your own research is just the beginning of many hours of effort you will have to put in to a swap for it to reach completion.

best of luck to you- I'm in the middle of a swap and it can tell you that it gets really ugly!