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Old 07-01-2017, 06:29 PM   #1
Asianjimmy
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Join Date: Sep 2011
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Default ej20g swap to 2003 wrx

i recently bought a ej20g for my 2003 wrx motor went dead. i was taking both engines apart today and found that the intake manifolds wont line up and i searched the threads and havent gotten a straight answer as if it will work or not. is it possible to switch over the cam gears and crank gear along with the sensors and get a custom made tgv delete to fit the ej205 intake manifold on it to run with a usdm manifold? is there even a chance to finding an tgv delete kit to fit this motor with the usdm motor? or should i just take the motor back and try and swap it with hopefully the right motor. at the time i believed it would work but seeing it is a phase 1 motor it wont. if anyone has any insight can you please let me know. thank you.
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Old 07-02-2017, 12:29 AM   #2
monkeyposeur
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03 WRB GD 205/22T 20G-XT

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You could probably swap the short block and use your 205 heads. If you can return it that would be the easiest option. Getting the 20g longblock to work will be a complete pain in the ass if not almost impossible.
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Old 07-19-2018, 04:04 PM   #3
Scoobydoobydude
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I am doing an jdm swap to my 2003 GG in a few days and have put a deposit on a 205 with no TGV and AVCS. Quite frankly I'm giddy. So I look at the web page 3 times a day like a little kid. I noticed a closed deck ej20g for sale, it's the first one I've seen up on the site and its got a td05 it's also about 50% less delivered.

My question is obviously... what the actual f.... wouldn't it be so much better to just get the EJ20G? Or am I just pissing up a rope here and begging for more pain? As it stands I'm looking at like 3k in parts: motor, new clutch, shifter bushings etc.

I have roughly 2 days garage time with my mechanic on deck.

Can someone break it down for all of us what the concordant operation is or point to some thread/s that explain it precisely?

As always Thanks in advance!
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Old 07-19-2018, 09:32 PM   #4
monkeyposeur
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03 WRB GD 205/22T 20G-XT

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Still the same story as the OP. You could swap in the 20G shortblock and use the heads and everything else from your stock 205, basically building a hybrid, but you can't use anything else from the 20G. The sensors are incompatible, the intake manifod is different, the heads won't work with your 205 manifold, etc. The td05 might not even work if it has the 90* elbow found on earlier subarus. You would need a custom tune if you use the shortblock. The 205 you put a deposit on should drop right in. Using the 20G shortblock will be more expensive and a pain in the ass and not net you any gains over a USDM 205. Yes, the closed deck aspect is nice but not necessary even at higher power levels.

Don't do it. Save your money and time and go the easier route. If you wanted to use the complete EJ20G longblock you would have to go with a standalone ECU.

The EJ20G was used in JDM 89-93 subies
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Old 07-19-2018, 10:40 PM   #5
Scoobydoobydude
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the 20g comes complete with ecu... would it it be worth it then?

205 also is complete with jdm ecu...
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Old 07-19-2018, 11:14 PM   #6
monkeyposeur
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The wiring is completely different on the EJ20G compared to your WRX. To make it work you would need the complete dash harness and engine wiring harness and ECU from the EJ20G, and merge it to your WRX wiring (which requires removing your WRX dash harness as well). You could pay iWire $800+ to do it or spend about 200+ hours doing it yourself and hope to god you did it right. Once you were done, you would have reverted your car back to OBDI and would not have the ability to tune the ECU for USDM gasoline or allow few if any modifications. You could spend another $500 for a RobTune EJ20G ecu which has two built-in tunes, one for 450cc grey top side feeds, or yellow top 550cc side feeds both of which are considered inferior injectors by many when compared to your current top feeds. Or you could buy a tunable ECU from the UK for about $1200 and use that with the merged wiring harness.

205 JDM ecu plugs right in to your existing wiring, but also would need to be tuned for USDM gasoline, and since you don't have AVCS (which requires some additional, simple wiring) there is no benefit to using the JDM ecu compared to your stock UDSM ecu. And the JDM ecu can have issues with connecting to the emissions computer in the US, which is why many people that run JDM ecus have to swap over to the USDM ecu every year to pass emissions.

The EJ20G also has no available options for cam upgrades, simple parts such as valve cover gaskets have to be sourced outside the country, and if anything goes wrong with the engine you are ****ed for parts. If the TD05 on the EJ20G went out, you would need to fabricate a custom turbo intake to handle turbos without the 90* elbow, or source another TD05 from someone who is hoarding one.

The EJ20G is a cool engine and is a great option for those wanting to swap a JDM engine into a first gen (USDM 90-94) legacy or GC and run a RobTune, but it is a terrible idea to revert your car back to 1990 technology. And good luck passing emissions since your car is now OBDI and impossible to hook up to the computer at your local emissions shop.

If the 205 that you are looking at has no AVCS keep in mind that you will have to turn the codes for the AVCS sensors off which will require a Tactrix cable and opensource software, or an AP. If you still have your stock engine, you can use your stock intake manifold and TGV motors.

Don't do it.

Last edited by monkeyposeur; 07-19-2018 at 11:21 PM.
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Old 07-19-2018, 11:23 PM   #7
91 RS RA
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^ +1 on this
Its like buying a late model Mustang and throwing in an old cast iron push rod engine in to it.
Can it be done, yes, do you want to do it, no.
Too much work and money for no real gain. Only thing about the 20G block is its closed deck.
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Old 07-20-2018, 10:48 AM   #8
Scoobydoobydude
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awesome thank you guys! This is exactly the kind of info I needed. My jdm 205 does have avcs and I'm going to hook up the wiring using iwire's guide. I totally understand now why it's significantly less expensive for the 20g.

I really honestly appreciate this kind of level headed slap down!

Many thanks
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