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Deeregamer's 2.5i--->gt build


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So my legacy decided that blowing a headgasket and spinning a camshaft bearing was a great idea 2 months ago. I was going to be reasonable and just throw another ej25 into it but turns out my Calif emissions engine is difficult to locate to begin with and very expensive by the time its in my hands. so i got to thinking "Why not build the car ive wanted to for the past 4 years of ownership?" So begins this amazingly difficult and convoluted journey of creating the car that no one wants to be possible. A once 2.5i with a turbo under the hood. So here it goes.
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yeah really need to consider starting with an actual GT. unless time and money are overflowing for you... it'll be a smarter that way. not saying its impossible, but its going to cost more than the GT you really want, AND at the end of the day.. it'll still be a 2.5i and likely decreased in value.
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So what am I converting to?

Ive just picked up a jdm ej20y longblock this past weekend with everything from exhaust manifolds to intercooler. Ive decided to go this first and foremost casue twinscroll but also because of how cheap it was to get. I could buy two ej20y's before i got one calif emissions n/a motor. also it is alittle off the beaten path. I always wanted to have a turbo under the hood of my car but didn't want it to be generic. Turbo kits from avo are too easy so i put myself against this challenge:spin:.

 

How do i plan on running it?

My 2.5i and its bulk harness are now useless to me. So i've decided the best way to run the ej is by converting to a Manual 5spd GT bulkharness first. I have a few questions with how this will work out though. Should my immobilizer and keys still work together with my new ecu? I've heard of people bring their car to subaru so they can start it again after changing just an ecu let alone my swap. Also do i need to change instrument cluster too? Id venture to believe that they are different but am unsure. Then i have those pesky exhaust avcs to deal with. I've found a patch in kit that has the 8 wires that run the left and right side sensors on the bulk side but need to call them tomorrow to confirm it will work with my application. If that doesn't work out i have about 6 inches of both the brown b20 connector and black b135 connector on the bulk side of the harness to work with. Ive already got the diagrams from the 04 jdm gt and have found the 4 wires on the b20 connector. Just need to find the second set of four. Otherwise is there anything different?

Transmission, clutch and flywheel

I want to be able to use my stock unit but realize it probably wont be up to the task at hand. also its a push vs pull or how ever it goes for the 06+ wrx clutch flywheel and pressure plate kit that i want to use. I think i may take another trip to the depot i picked up the engine from and source a wrx 5spd and matching diff that has the 4.44 final drive vs the 4.11 that i have now and any usdm lgt would have.

 

Otherwise i think thats kinda it for now. I honestly just want to get it running and driving by spring time so i dont plan on doing anything special yet. In the future i would like to do a few things but thaats out of my reach for the time being. If anyone has some insight on this swap and wants to lend a hand please feel free to type away. I can tell im gojng to need all the help i can get.

-Eric

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I know it would have been smarter to just get a Gt in the first place but i have already got myself into it. I have a group of friends that are as sick as i am and want my car to go fast too. Ive had this car for 4 years and she has gotten about 6 of my friends into turbos subarus so now they all want to help and return the favor by giving me a hand.
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Your ignition key is coded to the bcm and ecu. No corresponding bcm to ecu, no start unless you have a bypass.

 

Thanks for the heads up, that's a TIL for me. Another TIL is that 2005's actually have a CAN bus network :mad:.

 

Anyway, looking around just found this, looks like for us GT guys using a JDM v9 motor works with stock ECU because no exhaust AVCS:

http://forums.nasioc.com/forums/showthread.php?t=2372623

05 LGT 16G 14psi 290whp/30mpg (SOLD)

12 OBP Stock 130whp/27mpg@87 Oct

00 G20t GT28r 10psi 250whp/36mpg

22 Ascent STOCK

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Your ignition key is coded to the bcm and ecu. No corresponding bcm to ecu, no start unless you have a bypass.

 

In other words a visit to a North American dealer wouldn't fix this issue if not all pieces were gotten?

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The JDM ecu's didn't even have an imobalizer function. So in theory you should be able to get it to start. BIU and cluster will probably pitch a fit though.

 

There is a separate UART bus going between the BIU and ECU for this functionality. Actually if you wanted to get clever, you could run both ECU's to trick the system into working. Just feed the old ECU the bare minimum for the imobalizer to work, JDM ECU does the rest.

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Just noticed where your from, you should reach out to www.tuningalliance.com Mike or Brian may be able to help. They are about 15 minutes away from you in Vernon CT. just off exit 65 on rt84

305,600miles 5/2012 ej257 short block, 8/2011 installed VF52 turbo, @20.8psi, 280whp, 300ftlbs. (SOLD).  CHECK your oil, these cars use it.

 

Engine Build - Click Here

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Sorry i haven't been on here posting in a few days. I have been trying to balance finals coming up, work, and working on the car. so for the next few weeks i may be patchy on updating you guys. But back to fun things. I picked up a GT crossmember from a local scrap yard yesterday that was in really good shape. Took an hour today and cleaned it up. Got some rubberized undercoat on the bottom side and cleaned up a few spots on the top side. After that i got the old short block out with a borrowed hoist. The locating dowels fought me for a little while but a big hammer and punch ended that fight quickly. earlier today before i had some turkey i took the driver side control arm, swaybar endlink and tierod end off. i might try and drop the otherside later tonight once some family leaves. Im going to try and sit the motor in the engine bay this weekend so its off the ground and out of my already limited space i have in the garage. Oh i forgot to mention i put the car in the garage finally! cleaned out a bay and can now work in heat. Not sure i said this before but i also have the dash out of the car and when the engine is in the car i will take everything else that's in my way out so i can get to the bulk harness and extract that. I feel like that's a good way to describe that job haha. Gimmie a few minutes and i will get to everyones comments as alot of them are very useful.

Thanks for the patience and happy thanksgiving!

-Eric

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That's actually a solid build plan.

 

Go buy a G....he has longblock already?! "See ya good luck"

 

This is a bold endeavour my friend and hats off to you for putting something together.

Yeah i know that it is and thankyou. Its something I have planned out over the past 4 years of having the car in many different variations. Saw this JDM engine for cheap and thought "how bad could it be?". Now we are here haha.

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In other words a visit to a North American dealer wouldn't fix this issue if not all pieces were gotten?

This is what i had thought was the case? I really hope so or i might be going standalone if i cant make something work with the jdm ecu.

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The JDM ecu's didn't even have an imobalizer function. So in theory you should be able to get it to start. BIU and cluster will probably pitch a fit though.

 

There is a separate UART bus going between the BIU and ECU for this functionality. Actually if you wanted to get clever, you could run both ECU's to trick the system into working. Just feed the old ECU the bare minimum for the imobalizer to work, JDM ECU does the rest.

BIU? I had a feeling the gauge cluster would have to be swapped out of a gt car. If by clever you mean cheap im all in:lol:. Would i Have to run the engine side of the gt's bulk harness and only the imobilizer and interior control parts of my 2.5i harness to make it work? Ill have to look at a ecu pinout for both the jdm 2.0 and usdsm 2.5i and see if i can make heads or tails out of what would go into making this work properly.

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