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Discussion Starter #1 (Edited)
After thorough research and reading, I decided to bite the bullet and do an NA ej20 swap with an engine "from japan." I figure it would be useful to compile all the things I found, plus add some things I came upon along the way.

First, the "How To"'s I used:

Cribbie's JDM DIY The Original!

npstrs diy Our own resident DIY

freakmech's diy This is for a forester, but almost all the rules apply. Also, great pictures.

lerastabanana's DIY A newer DIY from an Outback Guy (Girl?) Has a solution to the PCV problem.

Some guy on Youtube. Mostly for motivation. Also, he names the Gates timingbelt part number to use.

Notes, or corrections on DIY's:'

*I BELIEVE the picture that cribbie has on the camshaft pulleys is backwards. The 1/3/1/2 markings are for the USDM, and not the JDM, though, someone posted that it is a difference between auto/manual configurations. Can't confirm that, though.
*You may not have to do anything weird for the pcv hose. It depends on your swap. I didn't. Lerastabanana has a solution to this on his DIY Reference Image
The coolant temperature sensor may be in the correct location for you, based on the engine you buy.


Things I learned along the way + parts compatibility:(pics later)

Engine Compatibility: I have an ej251. I bought an ej203, with an EGR valve. It's currently running fine (3 days as of 1.1.2017). I capped off the EGR hole in the head using the block off bolt from the 251. What matters MOST is the bolt pattern on the intake manifold - some ej engines have the manifold bolt pattern staggered, some are lined up. Make sure yours match, because you have to re-use YOUR intake manifold.
The valvecover gaskets: EXACT same. Save yourself some headache, don't be lazy - spend the 20 min and 20 bucks to do that while everything is easy to reach.
Sparkplugs: ej25 fit ej20.
Accessory brackets: In my case, all of the accessory brackets were compatible EXCEPT the A/C compressor. The bolts and brackets are smaller, and the compressor would most likely rattle if I just used that. I just reused the 251 brackets.
Timing components: With the exception of the crank gear and the METAL camshaft pulley, everything else is the same, and interchangeable. Note: the torque spec on the JDM 2.0 crank bolt is 94 ft/lbs, per Gates's instructions that came with the timing belt tensioner.


One other thing (for now): the gold bolts used for something on the JDM manifold (I think it was for the ignition coil) fits PERFECTLY in the holes machined in the flywheel. Stick them through the front "viewport" to lock the flywheel in place and be able to torque anything down you need to.

I will continue to add more information as I remember, or get the motivation to add the pictures I took. As always, feel free to let me know any extra information/links that you may have on the subject!
 

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Black GC8
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Put up some Dyno numbers when your done with it. I come from a Honda background so I love the high revving hi comp engines.
 

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Discussion Starter #3
Bahaha. This is primarily stock - it has nothing in the way of "hi comp" or "hi rev" anything.

However, sometime in the near future (6 months?) I will be attempting a projectLAMBDA tune, if nothing else to correct the displacement and raise the rpm juuussst a bit.
 

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Discussion Starter #5
Sorry for the late reply.

It feels like a Honda now. No torque (wife complains) down low, but man is it fun to wind out. I spin the engine to 6 k almost daily, and don't seem to have any issues.

It's been a full year, and there has been ZERO oil consumption. Only issue is that the water pump is leaking. I can't remember if I used a Gates water pump or not (or if I even swapped it out), so I'm doing a full kit again, but this time, bought an AISIN kit.

I year and a half isn't the best, but it ain't the worst either.
 

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2005 Impreza RS 2.5
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Any know what head gaskets are compatible with the ej203? I was reading that the head gaskets from the corresponding ej253 fits, but then I also read that the 02-05 WRX head gaskets were the ones to use.


Can anyone confirm this?
 

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Discussion Starter #7
Yeah, I'm finding conflicting information too. So these head gaskets may not be as reliable proof like the ej22, because mine may be leaking internally. I smell what I think is coolant on startup sometimes, and I may be losing coolant. It may not be the case because I just also did a water pump, so not sure about coolant consumption.



I am doing my research as we speak.
 

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2005 Impreza RS 2.5
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Yeah, I'm finding conflicting information too. So these head gaskets may not be as reliable proof like the ej22, because mine may be leaking internally. I smell what I think is coolant on startup sometimes, and I may be losing coolant. It may not be the case because I just also did a water pump, so not sure about coolant consumption.



I am doing my research as we speak.
I have found this twice already, stating to use cosmetic head gaskets, from a 02-05 WRX. I have only found one source stating that head gaskets are the same as EJ253. Attached is my reference for WRX HG’s.
 

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Discussion Starter #10
Yes I read that. Re-read it. Carefully

It looks like people are just speculating, and that none of those people have actually cracked open an ej203, nor do they know the actual thickness required.

Fel-Pro gives a recommendation for their part here:
Subaru EJ25 to JDM EJ20 Swap

So, while Fel-Pro offers a potential solution, even they aren't 100% certain. They're going off of the fact that ej25 have the same HG, regardless of Turbo/NA.


I found this on ebay a while back. Forgot about it, but here you go if you need it ASAP:
Six Star Head Gasket Set for Subaru Impreza Forester Outback Legacy 2.0 JDM | eBay


If in the future, that link ever fails, it is a link to a HG from Six Star Bernie.
It's on his Ebay account, but not his website:
Six Star Bernie | Subaru OEM Parts

Part Number: 11044AA483B
 

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'96 OBS
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So, I'm probably going to end up in a similar boat sooner or later. I did some digging through jp-carparts.com and found this:
http://jp-carparts.com/subaru/partlist.php?maker=subaru&car_baseid=F18019&type=B13&cartype=019&fig_id=006

That page seems to have some official Subaru JP part numbers for the EJ203 headgaskets, which might be helpful if Six Star isn't an option for some reason.

My question is: Have other people found jp-carparts to have reliable information? It seems like a treasure trove, and what info I've been able to confirm seems reliable, but I'm interested in other people's experience using it for research.
 

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I have a friend who is a master subaru tech and he told me that usdm ej205 head gasket is the way to go, so I think I will give that a shot.
 

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1996 imp jdm ej20 NA dohc swap
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Ok,



At this point we know that the jdm replacement gaskets found here Six Star Head Gasket Set for Subaru Impreza Forester Outback Legacy 2.0 JDM | eBay



Has the same design and everything as the usdm ej205 turbo gaskets. Genuine Subaru MLS Head Gasket Set Impreza WRX EJ205 2.0 TURBO OEM 11044AA483 | eBay


What needs to be verified is the thickness of the stock jdm ej201/2/3 sohc head gasket to confirm if the stock ej205 turbo gasket will be direct replacement or if the jdm route or cometic route will need to be taken.
 

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jp-carparts.com is giving me 11044AA651 as the part number for the EJ203 head gasket. It's also giving me that part number for the EJ207 (2004-2007). When I turn around and plug that part number into ebay, I come up with this:
Genuine JDM Subaru OEM '03-'07 EJ207 2.0L .56mm Thick MLS Head Gasket Pair RARE | eBay

So, that seems to point at the EJ203, EJ204, EJ20Y and 04-07 EJ207 head gaskets being the same thing and possibly points to a thickness of 0.56mm. Don't take that at face value though as none of these are primary sources.
 

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Please keep us posted! I'm sure it would be beneficial to a whole lot of people!

The heads are out getting machine and resurfaced currently, once I get them back I'll work on installation, but it might be right away. I also need to check which torque sequence to use for the head gaskets.


If I am using an 02-05 wrx gasket, I would assume to use torque pattern for that? I will check and report back.
 

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1996 imp jdm ej20 NA dohc swap
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The heads are out getting machine and resurfaced currently, once I get them back I'll work on installation, but it might be right away. I also need to check which torque sequence to use for the head gaskets.


If I am using an 02-05 wrx gasket, I would assume to use torque pattern for that? I will check and report back.

You would most likely use the same torque value and sequence that is used for a usdm ej251 engine.



~Josh
 

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1999 Subaru Impreza L
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Did you have to swap any sensors? Previous owner sold the car to me swapped with a EJ20 na.
Can you help me identify this situations?

-How come it doesn’t have any power the higher the rpm? Like it rises slowly even with WOT

-It doesn’t want to redline at 6200 so it cuts out at 5500 rpm. What does that mean?
 
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