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'12 WRX 5dr
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Discussion Starter #1
I realized that I don't really need a turbo swap done...I'm not interested in going in a straight line anyway. Most of what I do is AutoX and Touge, and I just thought I'd get a better torque/power curve with N/A.

Anyway, what are my options here? I've got a EJ251 out in my Impreza right now that has really bad rod knock...haven't pulled it apart yet to see whats good still but I'm pretty sure the block is gone...not sure about the heads.

I haven't looked into anything but Turbo swaps since I've contemplated a swap, so I have no idea where to start year. Not sure if N/A swaps require wiring harnesses and all that, or where to even get the motor from. Should I stick with the OEM motor and start a nice build that way?

Any help would be appreciated, thanks guys.
 

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95 RHD WRX
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Pretty much, Subarus are known for making great turbo motors. Because of this, their NA motors aren't exactly spectacular. Theres not much you can really swap in that would be an improvement...

Either way, its going to be expensive and the odds of you making much more than 200hp is pretty low without a very large sum of money dropped.
 

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STi V3 RA VLTD RHD
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694 Posts
There was a write-up on the web years ago about a guy who fully built an N/A EJ25 motor and put about 200whp down. When all was said and done, he had over $4k into the build-up... quite a large sum of money for 200whp when for alot less you could just get a fully reliable JDM turbo motor and stuff it in there... with the right turbo and accessories, a turbo motor will be just as responsive as an N/A one.
 

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1998 BMW M3
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personally i'd buy a H6 from a 2003 and stuff it in. probably end up less money than a built NA 25, but cost you more in time unless u is smart.

my other opinion is to keep stock motor and save money. saving money is good, lets u eat nicer and other stuff.

i should hella do a EJ30 swap, but need a GDA shell to play that game well....... :p
 

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MY99 GF4 EJ227 JDM 6spd
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my simple EJ22T swap w/ little TD04L turbo....
makes 178whp and 244wtrq. I have 6500revs to work with...coupled w/ a 2.5RS tranny. Power curve???? This peaks torque 3600rpms....drops to 120 at 6400. HP stay above 150whp 3600-6400. This was on a mustang dyno. CRANK figures are estimate at 260chp / 320ft lbs.

This is enough for me to hang w/ EVO 9's head to head. I'm pretty much keeping up with my torque and lighter weight. This also is enough and it BROKE my 2nd gear.

NA motors you have to rev high to make power.
 

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STi V3 RA VLTD RHD
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FuJi K said:
NA motors you have to rev high to make power.
Not necessarily... but the money involved to make low end N/A power is alot. High compression and longer stroke will make low end torque. Bump a 2.5 motor up to like 13 or 14:1 CR and run high octane and tune for it, and I bet you would have a monster. However, the cost to build such an engine, and the minimal power gains / responsiveness over a cheaper turbo motor makes it not worth the while unless you are in some sort of race class that prohibits turbo or gives some advantage (weight?) to N/A cars...
 

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2013 Subaru BRZ GBS
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3,187 Posts
Theres always the unexplored option...

JDM DOHC AVCS N/A 2.0 heads (from the current EJ20-R legacy models in Japan, with almost 190hp and a 7500rpm redline) on a 2.5 shortblock...
 

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needs more cowbell
95L, 07 2.5i, R6
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Just do the delta cam regrind with a dohc 2.5, and if you really need to, use an Emanage to make sure there isn't any pinging. A guy on here was putting 158 hp to the ground with the delta cams and exhaust as his only mods. I found it in a post that was like three years old. 158 hp to the ground NA would be great for autoX IMO.
 

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'12 WRX 5dr
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276 Posts
Discussion Starter #11 (Edited)
Any idea how much a delta regrind will run? I'm sure the heads on my car are still good...I may try to pick up a shortblock. While I'm at it I may just get some higher comp pistons. I'm not looking for much power, just a smooth powerband.

edit: just talked to a shop down in socal, they're pulling a motor w/ 50k on it for a swap and offered it to me for 800. I might just buy that ahead of time and then do the build from an engine stand.
 

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Ex-Mooderator
2001 RSTi, 2011 WRX Hatch
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ex25rs said:
Any idea how much a delta regrind will run? I'm sure the heads on my car are still good...I may try to pick up a shortblock. While I'm at it I may just get some higher comp pistons. I'm not looking for much power, just a smooth powerband.

edit: just talked to a shop down in socal, they're pulling a motor w/ 50k on it for a swap and offered it to me for 800. I might just buy that ahead of time and then do the build from an engine stand.
http://www.rs25.com/forums/showthread.php?t=53280

-- Dave
 

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'12 WRX 5dr
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Discussion Starter #15
For now I'm just looking for the Delta regrinds, borla headers, some kind of midpipe/axleback combination, a pulley of some sort, grounding kit, throttle body spacer, new wires and spark plugs (needed to do that anyway), and when all is said and done (I may add to this list) a tune.

RalliTek does tuning, corect? Does anybody else do it?

I've also heard problems of the delta regrinds (the more aggressive one I guess) throwing a CEL and having low idle. Will a tune fix this?
 

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2013 Subaru BRZ GBS
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homer09 said:
not so sure.... you need a deep redline to properly use such a short gearbox. with a 6200 rpm redline, he will be shifting all the time, losing plenty of time. anyway, short gearboxes are only good if you have a narrow band. a well built up NA engine, will have a FAAAAT power band (although low).
I'd rather have a longer geared transmission for auto-x. Especially a longer first and second gear...

With the 6250 redline, I end up stuck between 2nd and 3rd all the time at auto-x's :(

Either a 7000+ redline capable engine, or longer gearing... either one would work.
 

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'12 WRX 5dr
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Discussion Starter #17
Kostamojen said:
I'd rather have a longer geared transmission for auto-x. Especially a longer first and second gear...

With the 6250 redline, I end up stuck between 2nd and 3rd all the time at auto-x's :(

Either a 7000+ redline capable engine, or longer gearing... either one would work.
for truth, i always find myself way into 2nd often when i go for mountain passes.
 

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95 RHD WRX
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I was under the impression that there was a reflash out that could raise your redline on the ej25 to 7100rpm? I remember seeing some guy has some custom reflash that did that.
 

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The Silverback Mod
05 Black OBS
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derekthecynic said:
I was under the impression that there was a reflash out that could raise your redline on the ej25 to 7100rpm? I remember seeing some guy has some custom reflash that did that.
Unless your doing some solid head work (springs etc.) KaBoom! :sunny:
 

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derekthecynic said:
I was under the impression that there was a reflash out that could raise your redline on the ej25 to 7100rpm? I remember seeing some guy has some custom reflash that did that.
I believe the I-speed reflash can do that, possibly even the Perfect Power system... But theres no good reason to do so without internally changing the motor around.

Well, another 250rpms wouldnt hurt that much :p
 
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