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I found an ej25 engine with a blown head gasket for about $100. I was considering dropping it into my 2.2L coupe after a rebuild. Would it be a straight swap or would the additional displacement blow the ECU's mind? I do not want to change the wiring harness after seeing the ECS thread. I hate wiring. This would give me a chance to change the clutch and half shafts.
t
 

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97 2.5 obs, 98 Legacy GT Daily
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do you know what year ej25 it is? the 98 dohc will plug right in to your stock 2.2 wiring and a post99 sohc ej25 will require some minor modification.... i just put a dohc ej25 into my outback sport 2.2L and it just dropped right in and is currently running fine with the stock 2.2 computer.
 

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Discussion Starter #3
From seller "JDM 2.5L Cast into the block EJ 2.5", definitely DOHC from the pics. Came out of a legacy, year unknown.

What kind of differences are you seeing? Looks like only about 30 more hp.
 

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97 OBRS...wrx
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That is a nice swap. I have been running a 98 dohc in my 97 obs since around january. There is definitely a noticeable difference in power, especially if you 2.2 is as high of mileage as mine was. You can use your 2.2 ecu just fine as it is, but if you use a 98 ecu you can get a couple hundred more rpm from what i understand. I am not to sure of the differences between the 98 and down or the 99 and up motors asside from the dohc-sohc.
 

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staticchmbr said:
so the 98 2.5 will bolt right into my 2000 obs with no wiring hassles, eh? hmmmm...
I believe what they mean is you transfer your current engine harness onto the new motor, and that all the sensors and plugs will be in the same or close to the same positions as there are on the 2.2. the engine will run the same but with higher displacement. Your stock ECU has enough margin built into it to compensate for the extra air/fuel requirements of the larger motor. Keep in mind this all goes out this window if you turbo it but for an N/A application the 2.2 ECU can learn to run the 2.5 just fine. The only place you might run into problems is during open loop transitions where you might run a bit lean but I doubt it would be enough to hurt anything and would most likely add a few HP in the upper RPM range. Just post if any of that does not make sense.
 

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2000 OBS
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amorton said:
I believe what they mean is you transfer your current engine harness onto the new motor, and that all the sensors and plugs will be in the same or close to the same positions as there are on the 2.2. the engine will run the same but with higher displacement. Your stock ECU has enough margin built into it to compensate for the extra air/fuel requirements of the larger motor. Keep in mind this all goes out this window if you turbo it but for an N/A application the 2.2 ECU can learn to run the 2.5 just fine. The only place you might run into problems is during open loop transitions where you might run a bit lean but I doubt it would be enough to hurt anything and would most likely add a few HP in the upper RPM range. Just post if any of that does not make sense.

no no, makes perfect sense...but if i was to do a turbo, i guess i will have to re-wire the car to run a different ecu/standalone type system, correct?
 

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staticchmbr said:
no no, makes perfect sense...but if i was to do a turbo, i guess i will have to re-wire the car to run a different ecu/standalone type system, correct?
If you plan to go turbo later down the road than yes you will need to go either stand alone, WRX or STI Swap "motor/ECU/harness" or run a piggy back ECU such as the Perfect Power 6. It all really depends on how you want it setup what your power requirements are and what the emissions requirements are in your state. Mostly everyone will suggest a swap. They are reliable and emissions compatible. I bet people will even suggest you don't bother with the 2.5 motor and save up for a swap, well for how little a 2.5 motor can be had I would run that for a while see how you like it and in the mean time do your research on Swaps stand alone systems and every thing else out there. As far as bang for your buck I don’t think you can do much better than a 2.5 upgrade for now.
 

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New to me 2006 Blue Impreza
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I believe what they mean is you transfer your current engine harness onto the new motor, and that all the sensors and plugs will be in the same or close to the same positions as there are on the 2.2. the engine will run the same but with higher displacement. Your stock ECU has enough margin built into it to compensate for the extra air/fuel requirements of the larger motor. Keep in mind this all goes out this window if you turbo it but for an N/A application the 2.2 ECU can learn to run the 2.5 just fine. The only place you might run into problems is during open loop transitions where you might run a bit lean but I doubt it would be enough to hurt anything and would most likely add a few HP in the upper RPM range. Just post if any of that does not make sense.

Why would Turboing the motor not work?
 

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03 350z for now
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Because a 2.2 or 2.5 ECU will not compensate for the addition for a turbo. You must get a WRX, STi, piggy back ECU, or a stand-alone ECU system (preferred) like Amorton just posted. Did you read his post?
 

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New to me 2006 Blue Impreza
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Because a 2.2 or 2.5 ECU will not compensate for the addition for a turbo. You must get a WRX, STi, piggy back ECU, or a stand-alone ECU system (preferred) like Amorton just posted. Did you read his post?
Actually I missed his second post. I read it after I posted the senoir moment comment.:crazy:
 
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