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Discussion Starter · #1 ·
I want to put an NA ej25 in my big eye. Off the top of my head I’m thinking:
  1. Oil return from turbo to valve cover or pan
  2. Converted maf intake with WRX wiring harness n maybe larger injectors
  3. Lower boost pressure with 5lb waste gate spring n boost control
  4. Tune flash from the rom raider community
Your thoughts?

Thanks, Izzy
 

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If it were me, and I was dead-set on a 2.5L in that car, I would rebuild the OEM motor with a 2.5L block for a "Hybrid" build.

There is a reason most people do not bother with a NA longblock -- it's not up to the task of turbo duty (hell, the turbo motor is hardly up to that task).

Depending on the year, many NA 2.5L motors are SOHC which further limits aftermarket choices. If you are really dead-set on it, you will need a new valvetrain, new pistons with lower CR, and a standalone ECU to control all of the sensors.
 

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Discussion Starter · #3 ·
Hi thanks for the reply. We I was thinking it would still be fun even with low boost to not over stress the internals. I’ve got a stack of free EJ25 Sohc motors so not too worried about super performance durability. What sensors? I was going to use a WRX intake harness and try to move it over and match things up. My car isn’t avcs. Why stand-alone ecu? Isn’t the 2002 WRX ecu flushable/tuneable?
 

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Discussion Starter · #4 ·
My WRX has a knock. Easier still might be to put the WRX heads on an ej25na short block, lower the boost and tune.
 

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I’ve actually got two knocking 2002 WRX. So a little longer term my idea is to drop an ej25na crank in and use the 4 best rods n pistons to make a running motor. I’m really into low budget junk yard specials for learning cuz I have access to a bunch of free stuff. But to get the car running and learn some tuning etc I like the idea of a low boost stock 25 sohc.
 

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You can do what you want.

Compression ratio will be an issue.

2.0L heads should be machined to match the combustion chamber to the larger 99.5mm bore.

RE: ECU, sure the ECU itself is flasheable, but I'm not sure what channels and sensors the EJ25 SOHC carries over from the EJ205.

Perhaps you should first address what's wrong with the existing motor.
 
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