99 OBS EJ22 to EJ20T swap questions

[Natedoc808]

I have my flame suit on so here goes...

 

I've searched for the past 4 hours on here for EJ22 to EJ20T swap threads and came up empty handed. 

 

I'm looking to swap an EJ20T from a WRX 02-05 into my 99 OBS with an EJ22 to bring her up to spec with how she was supposed to be imported here into the states before the bureaucraps got in the way! 

 

Need to find a build thread which outlines which components I need to grab from the other car.

 

It's my understanding I would only need the Engine (duh), the exhaust components for turbo operation, and the ECM.

 

Does the 99 OBS harness plug directly into the WRX ECM/Engine Harness or do i need to do a harness swap? 

 

I have a good line on an EJ20T longblock with a TD0520g turbo, but has rod knock which I can rebuild no problem, have a shop with lift and cherry picker and am not in a hurry so I can build the engine/exhaust etc off the car until ready for install. I am just trying to avoid making a big mistake from a technical oversight with compatibility or missing something obvious. 

 

Thanks for the help, and yes I'm sure there is a thread buried out there somewhere. 

[djcommie]

They won't plug in at all, I don't think OBSs came with low impedance injectors (like the EJ20T does), nor does a 99 California spec OBS use an airflow meter. 

 

You basically need a donor car, or at least a front clip. Otherwise you'll be nickel and dimed to death. 

[Natedoc808]

I'm taking the the entire engine from a car, injectors, manifold, intake components and all. I was more wondering if the connections to the harness are plug and play status where I can swap the ECM into the system and plug the complete EJ20T in and haver her run.

 

The exhaust setup will be pretty cake with some welding and bracket fabrication and the 5MT is direct fit. 

 

Like I mentioned, I cannot find a solid thread on this swap. I may have to be the guy that does the write up. 

 

Thanks DJCOmmie

[Gloyale]

I'm taking the the entire engine from a car, injectors, manifold, intake components and all. I was more wondering if the connections to the harness are plug and play status where I can swap the ECM into the system and plug the complete EJ20T in and haver her run.

 

The exhaust setup will be pretty cake with some welding and bracket fabrication and the 5MT is direct fit. 

 

Hanresses are completely different.

 

Will NOT plug and play you need a full harness swap or a piggyback.

 

Stock OBS 5mt will not hold up long to EJ20g power.

 

Oh yeah, the front crossmember will need to be swapped with a turbo one.

Edited February 10, 2015 by Gloyale

[Natedoc808]

Gloyale, thanks as always!!!

[Natedoc808]

No wonder I haven't found this build thread, nobody wants to do it because of the full harness swap. So need to take the full dash and all. Guess I'll save up for a WRX 

[bratman18]

It's been done MANY times. Go on rs25.com or nasioc.com

 

Don't need the whole dash, but it can be done that way. There are companies that will do the harness merge for you.the rest is pretty much just bolt in.

[Gloyale]

Or you can thin the WRX harness down to just Engine stuff, then add it into the car and make a few power/gauge connections.

 

Disregard all the original engine wiring of the car, and run the harness "standalone"

 

This is like what we do when we put EJ engines into older subarus (80's, early 90's) where there would be really no other way.

 

Now of course since the car you have, and the donor WRX share chassis and most body wiring, you could do a full front harness swap but that would require full dash removal.

 

My personal preference would be the "standalone" method......beacuse then if you wreck the car of for any reason can take the whole motor harness back out easily and use in something else.  (Vanagon, Hovercraft, Swamp buggy, Riding Chipper or whatever)