Questions about JDM engines

[Erik W. Treves]

If you have, say, a 2.5 TT JDM motor, can you run a US OEM ECU and harness with it and then a Cobb tuner on top of that? or do you have to stick with all JDM ECU? Are there any pit falls for using JDM engines in our application that one might look for?

[508wrx]

This sounds like far more work than what its worth. Unique, sure, but not worth it. As long as I've been in the Subi community I've never heard someone doing this (in a subaru obviously). It sounds like your concerned more with really fast spool rather than big power, correct?

Also, not sure if this will help but every once in a while some useful info actually pops up here. Its the conversions page on NASIOC.

http://forums.nasioc.com/forums/forumdisplay.php?f=87

[metalmaker12]

a 2.5 tt turbo motor is wicked cool but a uncommon motor to use, a 99 BH5 Subaru Legacy GTB twin Turbo is awsome, but I am unsure on the tuning of it. It is not like a jdm ej207, or any usdm single turbo motors so it would have a different ecu setup to run both turbos. I would think you can use a stand alone type ecu to run it and have no problems with US emissions. I personally grab a version 8 ej207 to play it safe because it can run off a 02-07 wrx/sti usdm ecu. I could be off on the twin turbo ecu being different, but i am like 90 percent sure it is. I will conference my friend who is a veteran subaru tuner. He will let me know what's available. It is possible to use the twin turbo, I am just not sure of that jdm ecu on that engine as being something that one can get to pass US emissions.

PS: COBB is ok when you want to hide a tune from the dealer, but a opensource ecu reprogram with dyno runs is cheaper and way more refined. My friend has been doing these custom tunes for street and race cars 15 years. Wicked Innovations in R.I. Let me know and I will set it up when needed

[Mechie3]

Is there an OEM 2.5tt? I thought all the TT motors were 2.0. The OEM legacy TT was a sequential turbo motor so the ecj controlled extra hardware like the switching valves. Not sure if the usdm ecu has any extra outputs to.control those.

[Erik W. Treves]

yeah I missed typed it (JDM Subaru EJ208 EJ20 Twin Turbo )..although I saw this on ebay as well...06 07 08 09 10 11 WRX LEGACY FORESTER 2.5L TURBO EJ255 REBUILD ENGINE LONG BLOCK.....but the question still applies. Looks likeyou can take the JDM motor and just swap out to USD harness and ECU and sensors and it should work. Metalmaker...thanks...I think I am ok with the tuning aspect ;)

[RM1SepEx]

Erik

I would think that would be a very sound approach... buy a high mileage car, rather than total rebuild just insert a low mileage JDM motor and convert to the US harness and ECU, just like those who plug a JDM into their cars here in the US. I have many autocross friends who have gone this route though none with a Subaru...

One is putting bigger turbos etc in a mitsubishi 3000 GT AWD. Best to start with his 43K JDM engine and transaxle vs the 150K original for a high power build

There are many ways to skin this cat....

[metalmaker12]

Yea it's a 2.0 twin turbo, I followed your post
You don't have to switch out the engine harness on the ej207, there is one sensor that is not functional with a usdm dash harness and all you do is unplug that sensor. If you use a usdm dash harness there will be some repining of certain dash wire harness wires to run avcs (subaru variable valve timing). I have the Subaru scripture on file when ready and pics of what I have done before. IA Performance also sells a plug and play wire kit to convert 02wrx usdm dash harness to run a version 7,8,9 EJ207 with the jdm ecu or usdm. This has been done before,,, the twin turbo has too, but I have not seen it in person, or worked on one yet.
So if you have a usdm pre avcs donor (02-03 usdm wrx dash harness),a version7,8,9 jdm sti ej207 engine with jdm engine harness and jdm ecu (or you can use the usdm wrx ecu), you can make it happen rather easily. If we have to pass emissions test with the
818 in our states you might want to run the usdm ecu since a lot of the new emission
machines will not read the jdm ecu like some did before. If one does read the jdm ecu
than one could just get a jdm dash harness and plug and play. I am not sure of my 818
having to pass emissions in R.I, but I am guessing they will try to.
The only catch is that the 02 usdm wrx ecu will not run the avcs, the engine will run and not even through codes, but no electric variable valve timing till you put the jdm ecu in.
I will run the usdm one to pass emissions than well hmmm.
Erik, what motor are you thinking of getting

[Nuul]

I will run the usdm one to pass emissions than well hmmm.

I'm grateful I don't have to mess with that, we don't have tailpipe tests in my state. How bad is it in RI? If it's a sniffer test I've heard (but never tried obviously) you can probably get real close if not completely pass just by running E85 for the test.

[metalmaker12]

Yeah that is an opinion with the e85. It is pretty bad if you don't know someone, but I think with the kit car they choose who you have to go to as part of the registration process.