STI swap whats involved?

[turboleg]

Well I've always been tempted to do this. My goal would be to find a cheap STI front clip and scavenge for the rear diff (if I need it). But what I would like is the STI power plant and a 6-sp.

Here go all the questions:

So far the parts that I know I'll need are the:
STI power plant (whats the engine code for the STI?)
6-sp - and I'm guessing a different shift linkage?
ECU and wire harness

More questions:
-Does someone like Walboro make a pump that would allow me to use the stock fuel tank?
-What is the final GR of the STI? I'm wondering if I can use a legacy rear diff and x-member.
-will the SS front x-member hold up to a STI and will it fit?

Any other parts you think I would need, I know this isn't going to be a cheap project?

Any help is greatly appreciated.

[Subtle]

Got the Walbro with kit in my twgn.

[IronMonkeyL255]

Does someone like Walboro make a pump that would allow me to use the stock fuel tank?

Yes. I can't remember the part # off the top of my head, but that's what I dropped in when my stocker took a crap. If you do a search on here for my name and Walbro, it will probably show up.

What is the final GR of the STI? I'm wondering if I can use a legacy rear diff and x-member.

IIRC, it should be 3.9, just like our turbo legacies.

will the SS front x-member hold up to a STI and will it fit?

It will fit. All EJ series engines are basically interchangeable dimension-wise. ie: the STI engine will bolt right up. It will be far more of an issue getting all the other parts to fit right.

As to whether it will hold up, I would think so. The x-member is a pretty beefy hunk of metal. The only thing I'd worry about was any kind of corrosion/damage it may have seen in the years since it's production. If you want, though, you could probably remove it during the swap and check for damage, reinforce some of the more stressed parts, and fully seam weld the darn thing.


Just my observations. I haven't done this swap, but was considering it.

[turboleg]

Actually the biggest reason I said I wanted the 6-sp was because I was never sure if our stock 5-sp would work with the STI block. I haven't ever seen the STI block up close nor the 6-sp. Is the bellhousing the same on STI blocks and the EJ22T? Or perhaps a better question would be would a BC legacy 5-sp work with a STI block without super modification. I know that 300hp would be a huge strain on a early 90's tranny but I've been considering a dogbox for the project as it is. If I didn't need the STI drivetrain it would probably help...at least for now.

[IronMonkeyL255]

It will bolt right up. Subarus are like Legos.

[ericem]

But i wonder if the chassis will twist in half when u floor it? like will all the CV's break, and the transmission will go bang and the torque converter will break, and the whole drivetrain will be garbage? i really wanted to get a sti engine for my subaru legacy NON turbo AUTOmatic, i found one for real cheap in mint, but i dont know if my tranny and everything would handle it, what do u guys think?

[Manarius]

But i wonder if the chassis will twist in half when u floor it? like will all the CV's break, and the transmission will go bang and the torque converter will break, and the whole drivetrain will be garbage? i really wanted to get a sti engine for my subaru legacy NON turbo AUTOmatic, i found one for real cheap in mint, but i dont know if my tranny and everything would handle it, what do u guys think?

The answer to your first question: No. Not unless you really modded that STi engine. A stock STi engine doesn't have enough power to do the damage you describe.

And why you you bolt an STi engine to an autotragic? Seems like a waste of time to me.

[tris91ricer]

first off, happy thanksgiving. next. SEARCH!!

sti final drive is 4.44. there is usually an lsd on the diff, considering the front and center are lsd, as well. viscous coupling, non mechanical.

to do a proper sti swap, you need most of the engine and electronics, in order to use the 6sp which also has the dccd. the dccd is tied into a ton of stuff, so good luck wiring that.
the entire project should cost you about 10-12k. oh, you're gonna need a wrecked sti to have all the parts. it would be wicked unwise to swap the sti drivetrain and powerplant onto your legacy that has stock suspension and bushings.

oh, and search, we've covered this extensively in our discusions of the sti.
art is also a very good resource for sti knowledge.

[ericem]

But i wonder if the chassis will twist in half when u floor it? like will all the CV's break, and the transmission will go bang and the torque converter will break, and the whole drivetrain will be garbage? i really wanted to get a sti engine for my subaru legacy NON turbo AUTOmatic, i found one for real cheap in mint, but i dont know if my tranny and everything would handle it, what do u guys think?

The answer to your first question: No. Not unless you really modded that STi engine. A stock STi engine doesn't have enough power to do the damage you describe.

And why you you bolt an STi engine to an autotragic? Seems like a waste of time to me.

OK, this is my problem though, i love the way my car moves now, handles well, seemed to have ruled out the body flex, but there are many times when i wish i had more mid and top end, But there is plently of get up and go though, but the STi engine pumps out how much, 300hp? or a older one 250hp. I called around and i think i found a turbo engine with ecu for 700, but it was a EJ20abc? lol forget the lsat letter but he said it was turbo, and looked mint, with 50,000km tops, and a 3 month warrenty, with everything already on it, atleernator, pwoersteerings pump, ac, but i want to be sure of a few things, seems like a scam to me, but do the EJ20 turbo engine produce alot MORE mid and top end power?

[tris91ricer]

Now you're talking about two different setups. Really, please, search or I'll get mean.

The EJ20T is the USDM wrx block from 01-04. After that, they moved to the 2.5 block, ala ej25. The STI block has always been an EJ257, IIRC.

If you would like to go with an EJ20G, I highly recommend it. It's a closed-deck 2.0L with some pretty good capabilities. Not only that, but its not bad on the fuel consumption either. My daily has an ej20g with stock turbo heads and intake manifold, which gives it a higher cr, about 9:1. Personally, I wouldnt drive anything else, and for the cost, it can't be beat. At some point, your HP:$$ ratio comes into play, and it's always nicer when you smoke cars that have WAY more money dropped into them.

Speaking of MONEY - - Why would you take a 2-3k dollar car, and put parts into it that are from a car worth nearly 10x ? An STI retails for about 30k (low end) and your legacy maybe could fetch 3k on the open market. That's a difference of ~$27,000US. For half of the difference you could be buying a wrecked STi and parting it, but that's quite an undertaking.
How experienced are you at doing these kinds of motor swaps?

[jake15]

first off, happy thanksgiving. next. SEARCH!!

sti final drive is 4.44. there is usually an lsd on the diff, considering the front and center are lsd, as well. viscous coupling, non mechanical.

wrong, usdm STi's are 3.90 up until 06 then they are 3.454... the jdm 6 speeds are 4.11 and 3.90 with an option on the spec C's for the 4.44 gearing. 05+ 6 speed have a lsd front and rear diff 04's have and open front diff... the center diff is some type of electronicall controlled unit hence the dccd.

to do a proper sti swap, you need most of the engine and electronics, in order to use the 6sp which also has the dccd. the dccd is tied into a ton of stuff, so good luck wiring that.
the entire project should cost you about 10-12k. oh, you're gonna need a wrecked sti to have all the parts. it would be wicked unwise to swap the sti drivetrain and powerplant onto your legacy that has stock suspension and bushings.

you will need the wiring harness from whatever motor you get. to use the stock DCCD system is alot harder on a car that is not an 02+ the DCCD system ties into the ABS pump, all the ABS sensors, it has its own gyro sensor things under the center console, and a whole bunch more sensors, it is nearly impossible to wire DCCD into an older car just because of th retrofitting required for all of the STi components. you can usually get a rolled STi for around 12-12.5K

oh, and search, we've covered this extensively in our discusions of the sti.
art is also a very good resource for sti knowledge.

[jake15]

Now you're talking about two different setups. Really, please, search or I'll get mean.

The EJ20T is the USDM wrx block from 01-04. After that, they moved to the 2.5 block, ala ej25. The STI block has always been an EJ257, IIRC.


the USDM WRX block is actually an EJ205 from 02-05. usdm STi block has always been called the EJ257, but the legacy GT and forester XT and whatever else is a turbo 2.5 is an EJ255

[jake15]

Well I've always been tempted to do this. My goal would be to find a cheap STI front clip and scavenge for the rear diff (if I need it). But what I would like is the STI power plant and a 6-sp.

Here go all the questions:

So far the parts that I know I'll need are the:
STI power plant (whats the engine code for the STI?)
6-sp - and I'm guessing a different shift linkage?
ECU and wire harness

More questions:
-Does someone like Walboro make a pump that would allow me to use the stock fuel tank?
-What is the final GR of the STI? I'm wondering if I can use a legacy rear diff and x-member.
-will the SS front x-member hold up to a STI and will it fit?

Any other parts you think I would need, I know this isn't going to be a cheap project?

Any help is greatly appreciated.

there is no such thing as a cheap STi front clip..... unless you got the hook up expect to pay anywhere from 4,000 (for a V1-V2) and up the newer they get.

you can use the same fuel pump a WRX uses in the stock legacy tank

see my first post for the final drives.. and yes you can you a stock legacy rear diff

the front xmemeber is pretty much the same, so yes you can use it.

you're best bet would be a whole rolled USDM STi (easier to find wirng for, readily available parts, etc etc)

[tris91ricer]

only the spec Cs are 4.44?? Hm, guess you learn something new everyday.

What this guy needs to learn is that An STi swap takes time, money, and effort that few of us on this board have.

[jake15]

no.. the spec C's have an option for 4.44's as in you have to pay extra and they have to be installed at the stealership

and any swap is definitely not for the faint of heart... the wiring alone makes me run away

[The Scooby]

plus the stock turbo legacy pump puts out more lph then an stock sti, so you would be safe on the stock pump for a little while.

[turboleg]

Awsome guys. Lots of good info. I have a good starting point now.

[turboleg]

In case anyone was considering doing this...This may be a good "cheap" way of doing it. My goal was to do everything for under $10k. It seems reasonable for me to put 10 k into a car that will end up having 300 hp. I can't buy a mustang and push it to 300 hp for that here in NY.

But I digress. I have notice a few Imprezas that have STI swaps on ebay. A lot of these cars are going for $10k and less. Personally I think this is the way to go. You can look for a clip (like I was goin to) but you end up with a whole rolling chasis this way. Might be useful to drop a stocker back into the impreza and sell it for a couple grand.


Just a thought...haven't done the math for sure yet.