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Old 01-13-2001, 11:26 AM   #1
gimpster
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Question JDM vs USDM EJ20

What's the difference between the two? Or is there? I've heard that with the USDM EJ20 if I try to boost it more than the stock 13.5 PSI then I will have problems with the cam belt tensioner bearing failing. Also I've been told that with high boost I'll have problems with piston slap in the #4 cylinder. I'm new to subaru's and boxer engines and I'm waiting for my WRX to get delivered. In the mean time I'm trying to plan out my mods. I want to be at 300HP minimum, preferably 350-400HP. Can anyone tell me how they get around the above listed problems on the JDM spec EJ20 or is the USDM spec EJ20 different than the JDM spec? Also, what other problems should I expect when trying to reach those kind of HP numbers and what would you recommend as the "safest" way to get there? Sorry for the length of the post but any help would be immensly appreciated.

[This message has been edited by gimpster (edited January 13, 2001).]
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Old 01-15-2001, 04:58 PM   #2
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TTT
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Old 01-15-2001, 06:08 PM   #3
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Gimpster,
I try not to be of the "do a search" ilk, but I couldn't even begin to cover all the differences and optiions here. You should to some research on the generations and manifestations of the EJ20.

That said, a base USDM and JDM EJ20 will not be different internally. It is the Sti and RA versions that get HP goodies. With what you want (350-400) I have one suggestion:
Blueprinting! RA's have different cranks, cylinders, rods, spring, etc. etc. To build an engine ready for that boost you need to really build it and not just mod your stock WRX engine.
Or, you could just do an EJ25 swap and buy one of Shiv's kits....Happy researching.
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Old 01-15-2001, 08:03 PM   #4
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Or you can go to Rally Knight and get an EJ25 CARB pending turbo kit with a Motec for a little more!
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Old 01-15-2001, 11:38 PM   #5
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who/where is rally knight?
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Old 01-16-2001, 01:39 PM   #6
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Thanks for the replies. I've been doing a lot of research since posting this and I think that if I build an engine the way I'm going to go is with an EJ22 because of the closed deck design. And since I know there is already another thread going on this right now, I'll just read up on that and dig around some more. Thanks again for your help.
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Old 01-16-2001, 01:47 PM   #7
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I disagree. If you want closed deck, have Trey sell you a closed deck EJ25.

The big difference between the JDM and US domestic EJ20 is the US' lack of a variable valve timing cylinder head. Those tumble ports to improve cold-start emissions also look suspiciously to me like high RPM flow impediments.
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Old 01-16-2001, 02:44 PM   #8
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So what you are saying is that the US version of EJ20 and the JDM version of EJ20 basically has the same internals? Same pistons, rods, cranks, etc? Thanks.
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Old 01-16-2001, 02:50 PM   #9
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No clue.
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Old 01-16-2001, 02:52 PM   #10
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Colin,
As usual, you are correct. I should have been more clear that the USDM EJ20 we are about to get is the same as base EJ20's that have been in WRX's for the last few years in JDM and elsewhere..

Apexi,
as I mentioned above, STi and Type RA's have different internals,only the base models are the same.
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Old 01-16-2001, 03:28 PM   #11
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Someone suggested to me a JDM EJ22 with 2.5 heads. Would this be better or worse than a closed deck EJ25 for a big turbo?
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Old 01-16-2001, 03:41 PM   #12
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Displacement wins in my book when you start talking big bucks.

So long as you can source a forged 79mm crankshaft, go for 2.5L. And if not, still use the 97-100mm bore!
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Old 01-16-2001, 06:35 PM   #13
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well gimpster...if money is not an option a fully built closed deck 2.5 is impossible to beat..can we say JUN 2.5 Imp in new zealand? But out of the box a 2.2 is already closed deck...then 2.5 heads for more grunt...perhaps i was unclear before..sorry
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Old 01-16-2001, 10:22 PM   #14
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Basshead, I'm a little unclear on what the 2.5 heads do for the EJ22. Do they raise/lower compression or increase displacement or are they just a stronger head to use?

Colin(or anyone else): do you have any links to sites that list out the raw specs of the different Subaru engines (bore, stroke, rod length, compression ratio, etc.)
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Old 01-17-2001, 07:54 AM   #15
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gimpster, I have yet to see that type of data on the web. Not many people possess those manuals, and since they paid for them they generally aren't willing to distribute the information freely.
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Old 01-17-2001, 08:40 AM   #16
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ej25 heads on a ej22 block??

hmm..makes me think of 305 V8 heads on a 350 V8 block...it's supposedly jumps the compression on the motor...and still keeps it at stock specs (supposedly).

you thinking along those lines?
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Old 01-17-2001, 08:45 AM   #17
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Guys there were two EJ22 turbos.

One was the early 90's Legacy Turbo (before the FIA reduced Group A displacement from 2.2L to 2.0L). The cylinder heads on it suck, and yes either the DOHC or SOHC EJ25 heads would be an improvement, although DOHC would lower the compression ratio even further. The SOHC head is nearly identical in operation but it doesn't flow the same.

The other was the 22B motor, which was nothing like the Legacy Turbo at all. It used an STi4 cylinder head, DOHC and the best factory casting Subaru had at the time.

[This message has been edited by ColinL (edited January 17, 2001).]

[This message has been edited by ColinL (edited January 17, 2001).]
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Old 01-17-2001, 09:54 AM   #18
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How about a legacy turbo shortblock with Sti heads, turbo, etc.. Sounds like a recipe for 280+hp to me

The poor man's 22b!
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Old 01-17-2001, 01:25 PM   #19
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One can be bought from US-based engine remanufacturers in long- or short-block form for relatively little cash.

The other is mega-expensive and supposedly requires the VIN from an STi to purchase direct from STi in Japan.

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Old 01-17-2001, 02:18 PM   #20
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The legacy turbo block isn't a "bad" engine. In fact, the block is quite good. It's just been cursed with ill-flowing heads.

Put on some proper heads and you're in business
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Old 01-17-2001, 03:22 PM   #21
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what kind of heads would you recommend for the Legacy EJ22? Roughly what kind of cost would we be talking? Or could you just have the stock head Extrude Honed?

[This message has been edited by gimpster (edited January 17, 2001).]
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Old 01-17-2001, 04:11 PM   #22
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Well...
Cobb's reworked heads sell for a couple of grand if you want to go the full monty. A stock EJ22 or EJ25 head that you can install cams in yourself and whatever upgrade should be far less than a grand. And I am sure there are many options in between.
There is currently a tuner here in Nor-Cal starting a project with a mid 90's Legacy shortblock, but they are keeping the details
under wraps for now...
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Old 01-17-2001, 10:03 PM   #23
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I think their needs to be a distinction made between using the 2.5L heads on a N/A 2.2L block(ej22) and using 2.5L heads on a turbocharged 2.2L block(ej22) when talking about this posting.

It seems like their are both questions being asked at the same time.

Just a little clarification...
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Old 01-18-2001, 12:34 AM   #24
gimpster
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Colin: how can you tell the difference between the "bad" Legacy EJ22 and the "good" 22B EJ22 when shopping for an engine?

[This message has been edited by gimpster (edited January 17, 2001).]
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Old 01-18-2001, 04:00 PM   #25
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Could you go ahead and clarify it for me then, Aspen?
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