Installing EJ255 Legacy GT engine into 2.5i Legacy

[D0C]

Hey I'm new here. Been searching forums everywhere for getting a dohc motor into my sohc fifth gen Legacy. I can't find anyone who was crazy or stupid enough to do it, I do see a lot of 4th gens that have done it but no 5th gens. I bought the car piss cheap, like 500 bucks cheap. The motor is blown, and the car has a shitty cvt, money is no concern I want to have fun with this car. I buy many cars and fix them and sell them but something made me fall in love with this gal. The way it drove even with all the issues especially during the winter was just impressive. I had a lancer gts before this and many other awd sedans  and this just won it for me. I been looking for Legacy GTs around me in this generation but no luck. Just the fourth gen but I don't want to get one of those.

Before I ask my questions, the car needs a new wiring harness and ecu AND a new motor. It drove fine when I got it but every light is on the dash and the ecu had corrosion going on it and a bunch of other issues with a few wires being damaged too. It also had a bad strut and wheel bearing but all of those issues are resolved. So I need a new harness and ecu, the motor is blown.

Can I put in an ej255 into the car with no issues, and if I choose to what's everything I'd need? How about I go even stupider and consider a 257?

Will the cvt be able to handle the new motor (255) at its stock hp or will I need a new transmission? If so, what transmission do you recommend? I'm not afraid to manual swap it as it's not my first manual swap and I know the gt only comes in manual. 

If you guys know someone who has done this already please send them my way! Money isn't my concern, just want to have fun with this and want to know the advice before I jump into the money pit. Thank you! 

 

Once again this is a fifth gen 2012 Legacy 2.5i. And I was trying to "just buy a legacy gt" but I'd lowkey just have fun with this. 

[DrD123]

Are you looking to put an engine from a WRX or STi in it, or do you have access to something from a 5th gen GT?  There are some changes external to the block that might make it awkward (the engine mounts are different, and the turbo is a low mount/under the engine the way they did with the current engine in the WRX.  the rear mount looks to be the same, though. 

I am guessing you would grenade the CVT in pretty short order unless you were real gentle with it - they introduced the high torque version for the engines with a bit more power in them.  There's a poster here that put an STi 6spd in their LGT, but it was a lot of work!

If you can find a wrecked 5th gen GT that should have everything you'd need, but the 5th gen GT is pretty rare.

[D0C]

Ya the 5th gen GTs are mad rare especially in Michigan. I am looking for an ej255 from an lgt off ebay or jdmenginezone. I do see one listed on there atm. I honestly wouldn't mind modifying the chassis though, I literally have nothing to lose with that. Transmission wise I definitely want to pull that cvt out before I even bother pushing real power into it, I was thinking a 5 speed manual that comes paired with most ej255s. But hell I know the cvts are weak in the subies but thought itd be able to hold up for just a bit until i decide its time for a manual swap. I'll definitely have to take into account the clearance of a 255 off a wrx which I honestly never even thought about. Thank you for the help brotha. 

[Aphex28]

Your best bet would be to find a crashed 5th gen GT and swapping over everything including the pedal box, clutch master/slave and wiring harnesses. Would be completely straight forward and you'd be best off getting the brakes from it as well. 

You may have more luck finding a H6 donor and you take the driveline from that (Although still stuck with an automatic)

Physically, the EJ255 from the 5th gen LGT and an 08+ STI are very similar. Both have dual avcs and the same shortblock with the only real difference being that the STI EJ257 gets a better exhaust cam (Which you can swap over)

Aside from that, the LGT has a 2 piece oil pan with an oil scavenge pump for the low mount turbo,  plumbing and a difference in how the engine mounts. The Legacy doesn't have a traditional engine cradle and engine mounts the Impreza chassis do. 

Edited June 20, 2023 by Aphex28

[m sprank]

An EJ255 has never been done to my knowledge.  You would have to fabricate all new engine mounts and subframe/cradle.  Then the CVT would grenade in 1st gear from the torque.  If you have say $50k to make it work then by all means its your money.  Otherwise.....

[D0C]

11 hours ago, Aphex28 said:

Your best bet would be to find a crashed 5th gen GT and swapping over everything including the pedal box, clutch master/slave and wiring harnesses. Would be completely straight forward and you'd be best off getting the brakes from it as well. 

You may have more luck finding a H6 donor and you take the driveline from that (Although still stuck with an automatic)

Physically, the EJ255 from the 5th gen LGT and an 08+ STI are very similar. Both have dual avcs and the same shortblock with the only real difference being that the STI EJ257 gets a better exhaust cam (Which you can swap over)

Aside from that, the LGT has a 2 piece oil pan with an oil scavenge pump for the low mount turbo,  plumbing and a difference in how the engine mounts. The Legacy doesn't have a traditional engine cradle and engine mounts the Impreza chassis do. 

Ya I unfortunately don't have a crashed lgt 5th gen. Hell id rather buy one of that and just rebuild it at that point. However I did stumble across a post somewhere talking about how the guy had to install 255 from a wrx into his lgt 5th gen. Said it was fairly cheap and mostly everything fit. Only issue was the oil level sensor didn't fit since it was a different oil pan so his light was on. That wouldn't bug me tbh but ya the fear is mainly the transmission if I ever want to test drive it or just drive it carefully I don't want to tank it until I get it swapped manual. Manual swaps aren't too scary to me though, it will be my second one however, but I have a great set of hands to help me out. Just never been so hands deep with a subaru.

If this is the case tho why don't I just go with a 257? 

Also I just want to say thank you all for the help, I'm going to wait a few months mb by August to start this project if I choose to. It'll give me time to know the costs and how I plan to do this and if I do I'll keep yall in the loop. This is really the most respectful forum I have ever asked advice on. Thank you for not simply shitting on my thought, just gave me the advice I needed. Appreciate it guys! 

[D0C]

6 hours ago, m sprank said:

An EJ255 has never been done to my knowledge.  You would have to fabricate all new engine mounts and subframe/cradle.  Then the CVT would grenade in 1st gear from the torque.  If you have say $50k to make it work then by all means its your money.  Otherwise.....

What do you mean exactly by a 255 has never been done? Like installed into a base model legacy? The tranny is just a big band but ya I doubt it'll hold the torque you're definitely right. And ya I'll have a lot of fabrication to do but I'm sure I'll get that to work. Also I don't think it'll hit to 50k unless you're calculating labor which will just be me doing it in my garage. Obv some stuff will need to be done by a professional, but for the most part my dad is a retired mechanic so I have trust I can do most of it at home. But thank you for the advice! Appreciate the help!

Edited June 21, 2023 by D0C

[D0C]

Ok so another question, will the drive shaft fit the diff with a manual transmission off a gt? 

Edited June 21, 2023 by D0C

[m sprank]

Being a mechanic and a fabricator are two VERY different things.  Also keep in mind that your concoction is not DOT approved.  So, it is illegal to be on the roads.  You will be able to register it as the state probably wont inspect it.  But if its ever in an accident, you are liable for EVERYTHING. 

 

I stand by my estimate. 

 

No one has dropped an EJ255/257 into a 5th gen Legacy.  The engine cradle and mounts are different so they do not support a direct swap.  Major fabrication is required.  As with a 4th gen the cost to swap a complete turbo engine set up into a 2.5i is astronomical compared to buying the LGT.  What are your plans?  You reach out here as it is obvious you really dont know what you are getting into. 

 

If you swap to a manual transmission, you need the rear diff too.  Its an AWD.  You must match your diffs to the transmission for proper gearing.  Or, you rip the diff in pieces. 

 

Its a Subaru, not a HONDA. Dont treat it like a Honda.  Too Furious to be Fast. 

[D0C]

54 minutes ago, m sprank said:

Being a mechanic and a fabricator are two VERY different things.  Also keep in mind that your concoction is not DOT approved.  So, it is illegal to be on the roads.  You will be able to register it as the state probably wont inspect it.  But if its ever in an accident, you are liable for EVERYTHING. 

 

I stand by my estimate. 

 

No one has dropped an EJ255/257 into a 5th gen Legacy.  The engine cradle and mounts are different so they do not support a direct swap.  Major fabrication is required.  As with a 4th gen the cost to swap a complete turbo engine set up into a 2.5i is astronomical compared to buying the LGT.  What are your plans?  You reach out here as it is obvious you really dont know what you are getting into. 

 

If you swap to a manual transmission, you need the rear diff too.  Its an AWD.  You must match your diffs to the transmission for proper gearing.  Or, you rip the diff in pieces. 

 

Its a Subaru, not a HONDA. Dont treat it like a Honda.  Too Furious to be Fast. 

That's why I'm reaching out boss. To know what I'd be getting into. Again thanks for the help. I'll be definitely taking your advice into consideration. Like I said I'm new to subies. I come from Hondas and Bimmers. I find subarus to be much easier to work on as in fixing them but I'm obv not that in depth with them. I'm aware of how fast their motors fail but I'm here to learn.

 

If you're saying 50k can you give me a list of costs to why you say that? 

[m sprank]

You dive into an unknown.  A deep dark abyss.  We know there is the cost of the engine, transmission, driveshaft, rear diff and axles.  You need the turbo system and exhaust.  You will need an ecu and complete wiring harness as well. Then you have to fabricate mounts and a cradle at a minimum. 

Now the fun begins.  How to swap it all over and make it work.  You will undoubtedly experience unforeseen hurdles.  Exhaust modifications, possible mods to the subframe, etc.  Plus the electronics.  Do you need a BIU and immobilizer with the ecm?  If the car was an AT and now you swap to a MT, you have to deal with the clutch and loss of tcu.  The electronics are all intertwined so I expect some time spent there.  As there is no instructions or manual you get to figure it all out as you go.  Hours spent scouring electrical schematics.  With no outside assistance. 

I have performed similar swaps (with Subarus) and the cost is high.  Just figuring out how to swap a 6MT into an AT on a car that was turbo from the factory took me over a month of research and testing.  Cost was well over $5k labor and thats just the transmission aspect.  At todays rates and not giving discounts for learning as I go, its probably $10k+ with parts for a 6MT swap into an AT. 

Even if you can perform all the work yourself and engineer the entire set up yourself, its not street legal and you will pay far more than resale value of the car for the parts required to make it work.  If you dont already have all the necessary tools, they get expensive FAST.  Do it yourself with ZERO experience in the realm...  $25k+

Buy the car you want.  Dont try to build it.  Not with a Subaru.