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Old 06-19-2003, 08:47 PM   #1
Speedwagon
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Default Opinion on '91 JDM Legacy turbo EJ20

Ok, so I have this engine sitting around, not doing anything. It came out of my 1991 JDM Legacy turbo(while I was in Japan), so I know the engine is good. Always ran well, didn't smoke or anything.

It is going to go into my 1998 Legacy 2.5GT. I have everything I need(a battery and some gas, and I could start it as it stands. )

Now, the question is, what, if anything, should I do to it while it sits? It's been suggested to, at least, get it o-ringed, heads or block. Should I also get the heads ported? Anything else I should do? Ultimate goal is(for now, anyways), 250-300 crank hp. I know stock on this engine was around 220.

Also, I've heard there are alot of performance shops around in the Maryland/Virginia area. Could I(good idea?) have them do the work for me? And anyone have approxiamate costs to this kind of work?
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Old 06-19-2003, 09:00 PM   #2
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Ooh.. I am also curios to know.. My heads are hydraulic, but looking at alot of aftermaket stuff for the WRX, it seems they are now using springs for the valvetrain. Is there a performance difference in this? Why the change? Benefits of one over the other?
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Old 06-21-2003, 02:24 PM   #3
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I dont know if the JDM EJ20 block is open deck or closed deck. if closed, o-ringing isnt really necessary, however it doesnt really hurt. We o-ring open deck blocks because they are known to blow head gaskets even at low boost (ex. Darshu @ 3.5 psi)

Port and polish is certainly a good upgrade, since subaru heads dont flow very well, but in the world of boost, it hardly makes much of a difference for the money. This would be an optional thing. As I always tell people on this board, sometimes money is better spent elsewhere.

If your goal is only 250 hp, you are merely looking at minor upgrades. If I were you i would consider a larger turbo, injectors, fuel pump, and manual boost controller. Even w/o a larger turbo, i think you could see those numbers.

Hope that helps. Im sure other people on thsi board have better ideas, but for some reason the Aftermarket Forced Induction has been real quiet lately.

-Jake
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Old 06-21-2003, 07:11 PM   #4
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it's a closed deck block, giveaway signs are the grid pattern cast into large areas, whereas the open blocks are smooth all over except a tiny bit inside.

Personally, I think the legacy engine isn't all that good. Mainly due to the annoying hydraulic adjusters and lever arm followers. The engines are often tappety with a stuck adjuster.

The pistons are nothing great, the rods as normal WRX engine etc.

I don't know much about the NA ej25 heads though. But if I had DOHC heads on a EJ25, I would probably use them with some decent lower compression forged pistons and forget about buying a 12 year old engine.

Subaru heads generally flow well, certainly the turbo ones anyway.

Paul
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Old 06-21-2003, 08:29 PM   #5
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First, I'm not buying a 12 year old engine. I already OWN a 12 year old engine, as I brought it with me when I left Japan. It was cheaper to junk my car, then fix it(had a problem with the steering rack) and JCI it.

What would be the benefit of 2.5 DOHC heads, as opposed to the 2.0 DOHC heads?

And yes, it is closed deck, as the heads are not currently on the block.
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Old 06-22-2003, 04:17 AM   #6
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Im sorry, i didnt realize you had a 98 GT already. What Pavlo is saying is that you can pull apart ur Gt motor and put the DOHC heads on ur EJ20... theoretically you will get better air flow through the DOHC heads...

However, I am going to have to disagree w/ Pavlo, I dont think Subaru heads flow well at all, the DOHC's aren't that great of a fix either. But at any rate the DOHC is likely better than the SOHC head.

If, however u want to sell ur 98 motor, it will be difficult to get ur money w/o the head on it.. soething to considider.
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Old 06-22-2003, 08:03 AM   #7
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Just use the orignal EJ20 heads and if your looking to do a build up then you could upgrade the pistons and rods while you have it out. Not to mention that some people have talked about the EJ25 crank in the EJ20 motor to up the displacement however you would need to talk to an actual shop to see what is involved in that. If you do the pistons it will obvious mean changing and upgrading your rings which you would want to do on a high mileage motor anyways. Change all the bearings out for new ones (from Power Enterprise if you can) since you will be taking the thing apart. Then just put on bigger injectors, better flowing turbo and a more efficient intercooler. After that its all in the tuning. You should be able to easily meet your goal if you go to the trouble of rebuilding the motor.
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Old 06-22-2003, 01:24 PM   #8
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I've totally disassembled this motor. If anything I would get some pre1998 2.5heads or some 1997 or older WRX/STI heads.

The heads suck and everyone complains about them in aus. You should definitly save up and get new ones ASAP. once you've done that, you might want to upgrade the pistons. And thats about it. That block should handle about 400hp with that setup.

If you want to stroke the motor it's up to you. But I perfer the diplacement between 2.13-2.15 myself. You can rev to 9k with proper engine blueprinting.

Expected costs? Look around the price range of 4-5k for a decent longblock buildup (350-450hp).
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Old 06-22-2003, 06:13 PM   #9
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Ok, so far we have all pretty much agreed that I should replace at least the pistons. I'm guessing forged aluminum here. I'm sure if I do a search, I'll come up with some reviews and options on that.

We obviously differ on the thought of heads though.

To entertain my first thought here, why do some of you think the new 2.5 DOHC heads work/flow better than the 2.0 DOHC heads? Was there a redesign over the years? And stop mentioning SOHC heads.. I DON'T HAVE THEM. Yer trying to confuse me..

For the rods though, I was reading a thread that had claimed they were in fact forged steel. Is there still a need to upgrade if they are? Or is that too iffy, and just do the rods since the pistons are out anyways?

Naturally, when I need it, bigger injectors and turbo are a must. But I plan to push these ones to their limit, whatever that may be, with some damned good tuning first.

Bearings.. good thought, didn't think of that before. Save me headaches later.. but that's why I'm posting this thread. Collect all my thoughts together, so I can reference it and stop asking questions, that I've forgotten the answers to.

Cams: should I consider replacing them now? Or wait until later, and see how things go?

Crank... I know you've told me that before about swapping in the 2.5 one, so it is something I've considered. Supposedly all the crank are the same(in construction, at least), or so I've read in the mixed finding of this board. Reports have said forged steel, which I imagine is good for quite a few ponies.

Naturally, doing all this is a matter of money. I don't, at this time, know how much I'm going to put into this. I would LOVE to have a monster legacy.. a good 300+ wheel horsepower. But, money is the limiting factor, obviously. I have a 2.5 that runs just fine, so I'm not in dire need of the swap, it is just something I want to do. But please, the more opinions I have, the better I can make up my own mind.
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Old 06-22-2003, 07:08 PM   #10
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Speed,

The reason I mentioned 2.5 heads is because they are more available than EJ20 heads. You can have an easier time and is cheaper to finds USDM EJ25 heads(if you look). sure you can find EJ20 heads, but it's hard to find someone who will sell you just heads from an EJ20 that is pre 1997 (most of the time you need to buy the whole engine). Plus people like cobb tunning specialize in the performance advantages of the EJ25 head.
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Old 06-22-2003, 07:13 PM   #11
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Ok, see.. you are not understanding me. I have, in my possession, one complete, everything I need to run it, 1991 Subary Legacy GT wagon EJ20 turbo engine. EVERYTHING. From the exhaust, to the wiring harness, computer, sensors, and the engine itself, I have everything. I gutted my JDM(while in Japan) Legacy, and junked the body.

Also, I just found in interesting site:

http://www.rigoliracing.com.au/strokerengines.htm
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Old 06-22-2003, 08:51 PM   #12
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Speed,

I agree there is a miscomminication. But I'm trying to help.

From what I understand you want to:
-Build up the block of your car
-Increase flow of your heads via cams, pp, etc...
-get more hp out of the motor in general.


From what I see you have a gennerally good idea what you want to do with the block, albeit a stoker or not.

Next My concern is this. That EJ20 motor you have in your possesion does in fact have a much different head construction that later EJ20 heads. The concern was brought up by Pavlo. Those heads have "annoying hydraulic adjusters and lever arm followers. The engines are often tappety with a stuck adjuster".

If you opened the valve cover you'll see what he is talking about. Those heads are definitly not able to achieve anthing close to 7500+ RPM with increased boost (especially 300+ hp). The heads from 1993 to 1995 WRX have solid lifters and after that they used hydraulic. The USDM EJ25 (legacy and first months production of RS) 1995-1998 DOHC used hydraulic lifters, Thats why I recomend them, and better airflow can be achieved with PP and valve jobs.

As for cams, in a turbo car the money you put into some good cams does not outwey the return. 600 dollar cams for 30 more horses? it's up to you.

The crank is very strong, if you want to stroke it, ask about knife edging it as well. Se what they have to say. I would do it to reduce rotating mass and have a higher rev.

Another thing is you might want to switch over to head studs rather than bolts.

One thing I like about this motor is the Intake plenum is huge, if you could find a way to reverse the intake to face the front of the car. You could reduce the piping for IC by 2 feet!
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Old 06-22-2003, 10:07 PM   #13
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1st.. for the IC, I plan on using the air-to-water one that came with it, but upgrade to the MRT larger resevoir and higher flow rate pump.

2nd.. yes, it was VERY noisy in the last few months before I took it out, and it sounded like a valvetrain issue.. but was only noisy sometimes. I emailed COBB tuning about their stage 1 heads, and if my heads could be used in the core return and whatnot.

3rd.. I do plan on swapping to the studs, rather than the bolts.

Quote:
If you opened the valve cover you'll see what he is talking about. Those heads are definitly not able to achieve anthing close to 7500+ RPM with increased boost (especially 300+ hp). The heads from 1993 to 1995 WRX have solid lifters and after that they used hydraulic. The USDM EJ25 (legacy and first months production of RS) 1995-1998 DOHC used hydraulic lifters, Thats why I recomend them, and better airflow can be achieved with PP and valve jobs.
On this, I have to ask. You say hydraulic lifters.. but on a OHC engine, isn't the cam itself the lifter? Am I confused, or did I misinterpret you or something?(this was explained to me earlier tonight, so this is why I ask)
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Old 06-23-2003, 12:22 AM   #14
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for 250 ..hp i don't think you need to do the heads just a differnt turbo

and you are limited due the uptuned inlet so if you can find a TDo5 get one .. an you you can find one let me know i have been looking for more than 6 months

there is a set of sti side feed injectors in private right now good deal

i have the same motor in my 93 impreza .. i am trying to tune it with a tec 2 .. but having little success, i have low compression issues too

noah in salt lake has the same motor and had cobb do his heads . .not sure if its is running yet tho
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Old 06-23-2003, 02:31 AM   #15
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Speed,

Check out the following sites for the differences between lifters (solid and hydraulic):

http://www.grapeaperacing.com/GrapeA...lvelifters.cfm

and

for a pick

http://www.newcovenant.com/speedcraf...es/lifters.jpg


obviously I don't know how much you know about camshafts. But who really does anyway. Take a look and see what you can decifer out.
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Old 06-23-2003, 05:29 AM   #16
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Speed you could just pick up the older model WRX heads off of yahoo japan.
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Old 06-23-2003, 02:44 PM   #17
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i know there JUN does make a cam shaft for this engine ... and they are stupid expensive...
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Old 06-23-2003, 02:47 PM   #18
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if you live in a metropolitain area, any legit machine shop can make you some cams, the prob is knowing what angles you need.

But those will be money as well. Best thing is to go with regrinds at a domestic shop.
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