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Old 04-24-2018, 02:58 AM   #1
UncleLimpy
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Default EJ20X into a 2004 Baja Turbo

hey guys, newer member here. bought a baja to have a reliable car for when I move, then it lost compression in two cylinders about a month before the move. after trying to diagnose the issue for a couple weeks I decided I didn't have time to mess with it and went with a swap.

problem is, EJ255s are hard to come by and expensive, but you can get a 50k mile EJ20X/EJ20Y for under a grand. Plus, they make more power or whatever. not really something I cared about at the time, I just needed to get the thing running.

a few elephants in the room:
it has 9.5:1 compression
it uses a twin scroll turbo that isn't compatible with typical usdm intercoolers
it has dual avcs
it doesn't have TGVs. this is a good thing, but also puts you in limp mode

the solutions I used for these elephants:
93 octane, good e85 candidate if feasible
swap headers, up pipe, and turbo from the EJ255 onto the new engine
leave the exhaust avcs unplugged. that's literally it.
swap over the TGVs. I'm keeping the jdm ones for later, but I just needed to get it running.

the long and short of it is to swap everything from the old engine onto the new one. exhausts, coolant plumbing, intake from the TGVs up (so, the entire thing) all come over. I found I was able to reuse the motor mounts, but YMMV. the only non stock items I added were a catless UP and DP.

it's not a sexy build since I'm using the factory charge pipe, intercooler, TGVs, TD04, and other tragic parts on it, but when I turned the key for the first time it fired right up and I went for a drive.

i know this isn't much of a build thread or anything, but there is so much information out there on these swaps you've got more people talking about it than actually doing it so there's more speculation than anything of substance.

it works, it's rather simple, and the only code I got was from the o2 that was cut off with the oem downpipe.

you will need to get a tune, but it will idle, run, and drive gently right out of the box.

editing for a tidier lil writeup:
everything from the tgvs up including injectors and fuel lines come from the 255. the exhaust manifold, up pipe, turbo should come from the 255.
if you want you can take the tgv deletes from the 20x. mine didn't fit perfectly but I got them to work. TGV deletes will cause subarus to have check engine lights. there are many threads covering this.
if you want you can keep the 20x exhaust manifold, up pipe, and turbo. you will need to fabricate a down pipe. nobody makes one that fits. fabricating one is easy if you know what you're doing. you will also need a solution for the difference between the td04 and vf38
do not touch the cams, do not mess with the timing, do not worry about the exhaust avcs. the car will run fine without touching them. mess with them if you want to, but it's unnecessary.
you must get a tune. it's simple and should cost no more than $400.
if the old engine was blown then the turbo might be blown as well. td04s are very cheap. vf39/48s are pretty cheap and much better.
for sensors, be sure the plug on the 20x sensor matches. if not, exchange it. I'm pretty sure the coolant temperature sensor needs to be swapped.
there will be other minor things to bring over, they are easily spotted. one such thing is a block off plug on the rear passenger side where the 20x has a hose outlet.
do your rear main seal, valve cover gaskets. same part numbers as the ej257.
I suggest you do your charge pipe as well. eventually they wear and tear and are a pain to replace when the engine is installed. either do oem or a decent performance one, not cheap garbage.
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Last edited by UncleLimpy; 04-13-2021 at 06:36 PM.
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Old 07-09-2018, 07:34 PM   #2
Mreed6360
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That sounds pretty straight forward, for the ej20x did you have to swap the intake cams in from your ej255?

I was reading about that for the ej205.

I just picked up a clean 05 Baja XT with a bad motor and I'm exploring my options for future fun.

Also how does it do with that compression ratio and the non-twin scroll turbo?
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Old 08-07-2018, 05:24 PM   #3
Dustyxt
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I did this swap in a forester xt about 2 years ago and everywhere said it would be a nightmare. I did just like your build but with sti turbo,injectors and innercooler. Was very straight forward got 300whp on 91. This is as simple as unclelimpy explains and is a direct replacement for any ej255/57.I have personally done this swap 3 times with no issues but have never used the twin scroll. I'm panning on using the twin scroll on my current 07 wrx swsp
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Old 08-07-2018, 05:45 PM   #4
Mreed6360
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Thanks for the encouragement Dustyxt, I'm going with the ej20x for sure, and I'm thinking I'm going to keep the twin scroll.

I'll update this as I go, it's going to be fun!
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Old 08-22-2018, 07:31 PM   #5
03WRX95
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Bump. Did you have to swap the intake cams? I’m in the same boat. I picked up a 05 baja with a blown 255 in it and I can’t decide wether to swap a JDM ej205 or the ej20x.
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Old 08-22-2018, 07:43 PM   #6
Mreed6360
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I just yanked the engine last weekend, and I decided I wanted to go the 20x route for sure. It sounded from unclelimpy that doing the cams wasn't necessary. Which is good because my cams are destroyed, tons of wear on the cams and journals.

My tentative plan is to try to go all in on the ej20x, I ordered one that should have part of the jdm downpipe attached, and I'm going to get that grafted onto my US downpipe.

Fingers crossed I'll do some more updating this weekend and next, my new to me engine should be here next Thursday
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Old 08-22-2018, 09:15 PM   #7
Mreed6360
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Here is what my cams look like, I'm not an ASE certified mechanic, but I don't like what I'm seeing. When I pulled the cam caps the oil that was between the caps and cams had a distincly gritty feel.
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Old 08-23-2018, 12:22 PM   #8
subyrally
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the cams in my Baja were like that when I pulled apart the engine. I thought it was from being over-torqued when they replaced the head gaskets at the dealership before I bought it. I broke three or four bolts trying to get the cam caps off...

one of these days, I will have the time to go back to the shop and finish putting my Baja back together. I am also putting in the ej20x, but probably going to go with the stock turbo since I don't have the rest of the exhaust to fit the twin scroll turbo, just the manifold and up pipe.

I have an old ej20 from an 02 wrx in my storage, I am going to pull the exhaust cams from it to put into the ej20x so I don't have to worry about the oil passages in the avcs cams. fingers crossed that those cams will work properly.
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Old 08-23-2018, 12:32 PM   #9
Mreed6360
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My ej20x showed up today, a whole week early! I won't be able to dig into it until after work, but I can already see through the shrink wrap that I'm missing the intercooler and top bit of the downpipe. Items which I specifically asked the seller about and was told they were included.

So I'll find out if the seller can get them to me, or plan B use my original manifolds and turbo which I don't want to do.
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Old 08-25-2018, 02:06 PM   #10
Mreed6360
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The engine seller says they have the intercooler, and are looking for the downpipe flange. So I should be set to move ahead with the ej20x intake/exhaust and turbo setup. Even if they can't find the down pipe, I can get a flange off of eBay and get that welded to my downpipe.

I did more research into using AVCS cams in non-avcs applications, I can't reuse my ej255 fixed exhaust cams due to their condition. And the resting state of the AVCS cams is not the same as the fixed cams normal (and only) position.

So when I replaced the timing belt and pulleys I set the exhaust cams one tooth counter-clockwise. To better match the normal position of the fixed cams. It's a little weird, but it should work.

I also ordered a Tactrix cable so I can tell the ECU not to freak out about the missing TGVs.

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Old 08-26-2018, 08:34 PM   #11
Mreed6360
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Weekend update, I took the harness off of both engines, and swapped the ej225 onto the ej20x. It's not a perfect fit, a little snug, maybe with more clever routing it would be better, but everything is getting where it needs to go.

I need to make a bracket for the map sensor, it lives in a different spot on the ej20x. Also the boost control solenoid lives on the intake manifold instead of the firewall. So I'm going to extend the wiring to the new location.

But so far no really bad snags ***129310;

The vf38 that came with the new engine seems healthy, so I'm going to leave well enough alone there.

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Old 09-04-2018, 09:40 PM   #12
Mreed6360
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Got into things further this last weekend, the throttle body that came with my ej20x was gross. A fair bit of carb cleaner and wd40 seemed to do the trick. But if it had issues, I'll know why.

I also went ahead and dropped the motor back in.

And installed my trans cooler, I think I over bought this, I could have gone down a size.
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Old 09-07-2018, 01:15 PM   #13
ds2198
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Quote:
Originally Posted by Mreed6360 View Post
Got into things further this last weekend, the throttle body that came with my ej20x was gross. A fair bit of carb cleaner and wd40 seemed to do the trick. But if it had issues, I'll know why.

I also went ahead and dropped the motor back in.

And installed my trans cooler, I think I over bought this, I could have gone down a size.
Anymore updates? Been considering trying this in my '06 WRX.
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Old 09-20-2018, 11:50 AM   #14
Mreed6360
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Oh man, it's going, I've been busier than normal over the past few weekends, so it's been little weeknight progress here and there.

I cut the flange off of the ej20x downpipe, mocked up my gauge set up, installed gauges in the pod. And test fitted the downpipe/exhaust. It's going to need some customization. I was hoping that the turbo would sit close enough to where the old one was, but the position and angle are a little off.

Not pictured, due to darkness, I adapted the ej20x PS pump to the Baja PS lines, (10mm compression union). Installed radiator and finished connecting lines to the trans cooler ( I mounted an aftermarket one in line with the OE one). Ditched stock oil pressure sensor in favor of a proper sensor, used a variety of npt and other fittings to remote mount the sensor due to alternator clearance. Also Installed alternator, ac comp, starter motor etc.

Things I still need to do:

"Custom" Downpipe

Run wiring to relocate the OE o2 sensor that used to be on the header to the downpipe.

Wait for the intercooler bracket from eBay and then see what else is missing from that setup. I don't think much.

Then it's wire whatever else I have forgotten to wire, aaaaaannd it should be good.


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Old 09-20-2018, 12:09 PM   #15
Mreed6360
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I'm really curious to see how this works out. Everyone that I've read about replacing their EJ255 with the EJ20X have just used the long block and the headers and accessories off of the 255. And apparently it works, and I'm not saying it's wrong.

But I really wanted to know what could be done with using as much EJ20X as possible for my budget/skill level. Once done it will be EJ20X from the rubber intake hose off of the airbox to the downpipe flange on the turbo. Just the wiring on the engine and a few sensors will be EJ255.

Some pieces I've had to hunt for, and some things could be done nicer or more correctly with more budget to that area. I haven't gone full cheap, but I have gone cheap in some areas to spend in others.

Once I get it done I'll post the spreadsheet with the costs of everything. I've been pretty anal about keeping track of what I've spent.
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Old 09-21-2018, 04:19 PM   #16
thejerc
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For the wiring, have you ever gotten hold of the wiring diagrams for the EJ20x motor or ecu pinouts?
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Old 09-21-2018, 04:57 PM   #17
Mreed6360
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No, I'm using the stock Baja ecu and harness. I swapped sensors over to the Ej20x as necessary. I have an aem wideband and tactrix openport to make the ecu play nice with the AFR/ timing and not puke check engine lights.

I'm leaving the exhaust avcs inactive.

I considered getting the ej20x ecu ( I live in an area without emissions checks, so I have some options that others don't) and running wires for the avcs, and all that. But then I'm not sure if I could tune it. I had read that Jdm ecu's didn't like the US tuning tools.
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Old 09-21-2018, 05:04 PM   #18
thejerc
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Alright I see! I'm asking because I'm currently in the process of doing this swap in a 2007 Legacy. I have the JDM ecu and want to use it with the dual AVCS. I just cannot seem to find any of the wiring diagrams/pinouts! I'm in Québec, Canada so no emissions testing!
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Old 09-21-2018, 05:46 PM   #19
Mreed6360
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I found some of it somewhere, when I was thinking about going that way, I'll check though my bookmarks and see if I have a link to it or something. I remember at least part of it was out there, some guys were using the JDM ecu with the US harness and reusing the TGV wires (re pinned in the harness) to signal the exhaust avcs.
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Old 09-21-2018, 07:08 PM   #20
thejerc
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That would be amazing! I am also using the USDM harness. Just wondering what would need repinning. Thank you for your feedback!
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Old 10-05-2018, 06:28 PM   #21
UncleLimpy
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Thanks for the hijack Mreed, I'd completely forgotten about posting here so I'm glad you're keeping it alive. I think we might be the only two EJ20X/Y bajas in the world

Not much to update since I posted other than it's driving like a peach. I've just bought a VF52 I'll be installing along with the JDM TGV deletes, and will be getting a tune so we can finally get into some hard numbers.

The weak link I feel like will be that I'm running the stock intercooler, but I don't want to make over 300whp, I'd be very satisfied at 250 given I'm running the 5 speed. I should be able to achieve this.

To answer your question on how it does with the compression: I do not know. I have not tuned it yet and will have to get back to you. When I get it dyno tuned I'll make a nice tidy writeup about the whole thing.

I did not swap any cams or adjust the position. I know you can, and I think Mreed was smart to advance the exhaust cam a tooth, but again I'm simply not interested in pushing max power (yet.)

The main purpose for this post was to just say that it can be done as simply as just about any other swap because when I was searching for information everything was so damn convoluted.

I'm excited to see what Mreed comes up with using the JDM twin scroll. It was my understanding that one could use that easily if they wanted to go FMIC, so it's cool to see the process to getting the TMIC working.
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Old 10-13-2018, 01:04 PM   #22
Mreed6360
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Awesome! Glad to hear it's working for you. Also glad you don't mind the threadjacking . I'm getting my Downpipe welded up today, so I should be in business soon. Here is a pic of it tacked together. I'll go into more detail soon about how it came together, I'm away from home at the moment.
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Old 10-19-2018, 10:03 PM   #23
Mreed6360
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I'll post some more progress pics in the morning, but in the meantime, funny thing about going full ej20x from the ej255.

The Baja / ej255 has the fuel pressure regulator under the intake manifold.

And the ej20x has it on the fuel lines way outside of the motor. I noticed when I went to run the vacuum line to the FPR and realized it was not anywhere on my setup .

It's not a problem if you use the ej255 intake manifold and fuel setup, but it is if you are doing the setup I am.

I thought it was worth mentioning if others follow in my wake.

I'm planning on cutting the return fuel like and relocating the stock Baja FPR to the ej20x location. It should work fine I think.
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Old 10-22-2018, 03:54 PM   #24
Mreed6360
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Gauges in and wired, nearly everything in the engine bay connected. Still need a non-broken bypass valve (waiting on the slowest eBay seller ever). Also the vacuum line to the brake booster is hacked together, but it will work for the moment.

Once I get the downpipe back from the shop that is welding it for me I should be in business!
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Old 12-11-2018, 11:33 PM   #25
Mreed6360
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Oh man, it's been a bit, been busy. But, I got a bypass valve, and hilarious hacked up downpipe welded, and got it out and running!

I used my openport 2 to tell the ecu to not worry about the missing tgv's or pcv. I am also missing the signal from the rear o2 sensor, which is odd since it is still present. I might have damaged the wires to it. Or the sensor could be bad.

The stock map with this engine is OK, but has room to improve. (I'll post some stuff when I can get it off of my computer, posting from my phone) Comparing the stock Baja rom to the JDM legacy that the motor comes from shows some interesting differences.

Notable areas, intake Avcs timing (the Baja is ultra conservative), wastegate duty cycle, target boost (not surprising really, different turbo) I'm getting it dialed in now, trying to log in the evenings when I can, then edit the rom the next day during my lunch break, and reflash the ecu after dinner.

I'll try to get more pics and or data up this weekend, but I would say it's a success!

The cool part was that the stock ecu rom was driveable, the AFR was pretty decent, and only a little bit of ignition timing was being pulled, and the learning fuel trims were 5 percent or less.
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