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Old 06-01-2015, 03:41 PM   #401
ArcticWolf
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Default N/A power white paper, long, please critique.

Hi folks, looking for a sanity check. On a 2006 2.5i with stock redline and cams, is there any point in going with the TWE high output (2.5") header offerings, or am I better off sticking with the 2.25" super sports for a ST* autox car?

Alternatively, am I missing something fundamental about the way those 4-2-1's move the power band?
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Last edited by ArcticWolf; 06-01-2015 at 03:51 PM.
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Old 06-01-2015, 03:48 PM   #402
williaty
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There is no 2005 2.5i.

Do you mean 2005 2.5RS or 2006 2.5i?

If you mean a 2005 2.5RS, then things will improve dramatically with the High Output headers (which is what I have). You'll get a TON of extra torque all through the power band. However, the biggest gain is the fact that they keep breathing up close to 7kRPM. If you're not raising the redline, I'm not sure if the SS would be better than the HO. I'm sure if you call Tom at TWE, he'll discuss it with you.
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Old 06-01-2015, 03:51 PM   #403
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Meant 2006, defeated by phone keyboard once again. Editing original...
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Old 06-01-2015, 03:57 PM   #404
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Quote:
Originally Posted by ArcticWolf View Post
Meant 2006, defeated by phone keyboard once again. Editing original...
With the 2006, I'm really not sure what you'll see on stock cams, let alone vs that stock header (which is MUCH better than the older stock header). You definitely need to talk to Tom at length about your goals and limitations for the car.
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Old 06-08-2015, 03:32 PM   #405
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Good write up for sure!
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Old 06-11-2015, 12:30 PM   #406
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https://youtu.be/zcoE9U7M5wU

Here is mine. I have since added Area1320 TB spacer, Grimmspeed phenolic spacers and grounding kit as well as removing a crap load of weight. Havent got it re-dyno'd though
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Old 12-08-2015, 01:04 AM   #407
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Quote:
Originally Posted by gotboost02 View Post
https://youtu.be/zcoE9U7M5wU

Here is mine. I have since added Area1320 TB spacer, Grimmspeed phenolic spacers and grounding kit as well as removing a crap load of weight. Havent got it re-dyno'd though
Any update? I'm very interested in your 2.5 NA build.
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Old 12-08-2015, 02:27 PM   #408
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Quote:
Originally Posted by Sgt.Gator View Post
Any update? I'm very interested in your 2.5 NA build.


Getting stuff together for the fuel cell swap over and upgrading the rear suspension with a new swaybar and stout mounts as well as lateral links and arms.

http://www.rs25.com/forums/f145/2222...-racing-2.html
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Old 05-19-2016, 05:14 PM   #409
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Does anyone have any info on the 300hp motor in the original post? The link is broken.
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Old 01-17-2017, 11:25 PM   #410
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Quote:
Originally Posted by andys View Post
Points taken.... except the one about facilities. My work is all done in a rain soaked alley in urban Vancouver. Facilities, no. Dirtbag swapper, all the way.

But I must warn you - I've got the dirtbag's low$$ power swap underway...

EJ25 DOHC, w/turbo manifolds, w/a VF10 running no boost control (direct manifold fed wastegate actuator - 5PSI), no intercooler, modified NA subframe all running on a MAF based OBDI 1.8 NA ECU with a low$$ programmable look up table based MAF AFR compensator (which can be adjusted to pass emissions).

..... but that's another thread in another forum I guess!!
i want to read the write up of this swap in detail...that would be interesting as hell...
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Old 01-18-2017, 06:32 AM   #411
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Originally Posted by livinon2wheels View Post
i want to read the write up of this swap in detail...that would be interesting as hell...
Me, too, Livin!
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Old 05-05-2017, 09:37 PM   #412
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Anybody here has ported and polisshed their headers?
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Old 05-06-2017, 12:01 PM   #413
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It would be interesting to know how these power gains stack up against current WRX / STi numbers.
If they're pretty good, I may consider picking up an NA from a junkyard and doing a full teardown and rebuild with Stage1/2 components and just doing a swap out. It would let me put the money in when I have it, a 'little' at a time.
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Old 05-08-2017, 12:17 PM   #414
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ScooBear... "Stage1/2 components"?
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Old 05-08-2017, 01:24 PM   #415
Charlie-III
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Quote:
Originally Posted by ssssssantimonio View Post
Anybody here has ported and polisshed their headers?
As I said in another thread, nothing really to port on tube headers. Make sure the header inlet/flange is a bit bigger than the head outlet, make sure the exposed end of the tubes is pressed against the ID of the flange. A small ballpeen hammer helps with this.
Polishing the outside is for looks, won't hurt or gain anything.
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Old 05-08-2017, 11:22 PM   #416
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Originally Posted by PA-Outback2000 View Post
ScooBear... "Stage1/2 components"?
(Stage 1 to Stage 2 components)
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Old 05-09-2017, 09:53 AM   #417
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i mean what engine parts are you considering stage 1 and/or 2?
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Old 05-10-2017, 12:28 AM   #418
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Quote:
Originally Posted by PA-Outback2000 View Post
i mean what engine parts are you considering stage 1 and/or 2?
Not entirely sure at this point. I only have this white paper and the associated links to go by for reference at this point. Once I have more money, I'll of course perform a lot more research.

On a side note, knowing next to nothing about the actual mechanical makeup of a Subi engine, can the 2.5 na be resleeved? Bored over? Would be nice to bump it up to a around a 3.0L. No replacement for displacement, after all. Just a thought that crossed my mind while driving around today.
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Old 05-11-2017, 04:55 PM   #419
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ScooBear... N/A's won't make gobs of power. Bolt-ons and cams on a SOHC 2.5L will be somewhere around 225HP at the crank. this is my build...

http://xcceleration.com/imp-gallery-...back.25.na.htm


adding high-compression pistons/internals, head work, throttle body, intake manifold, etc MAY get you around 265HP at the crank. i know of only 1 that made reliable high power as N/A...

http://xcceleration.com/imp-gallery-rs.htm


XXYYZZ motorsport had one that made near 300HP at the crank, but ran like crap and blew up.
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Old 05-11-2017, 06:02 PM   #420
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Quote:
Originally Posted by ScooBear View Post
Not entirely sure at this point. I only have this white paper and the associated links to go by for reference at this point. Once I have more money, I'll of course perform a lot more research.

On a side note, knowing next to nothing about the actual mechanical makeup of a Subi engine, can the 2.5 na be resleeved? Bored over? Would be nice to bump it up to a around a 3.0L. No replacement for displacement, after all. Just a thought that crossed my mind while driving around today.
You can stroke it to 2.7.
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Old 06-24-2017, 11:18 PM   #421
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Originally Posted by Rally_wgn View Post
Thanks, its good to see ppl still read this.
Almost done wading through the crap.

It's kinda disconcerting - new member, seriously considering owning a Subaru, looking at popular informative forums, and get treated to pissant bickering.

Oh well, working my way to the current posts!
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Old 06-25-2017, 12:16 AM   #422
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Quote:
Originally Posted by PA-Outback2000 View Post
ScooBear... N/A's won't make gobs of power. Bolt-ons and cams on a SOHC 2.5L will be somewhere around 225HP at the crank. this is my build...

http://xcceleration.com/imp-gallery-...back.25.na.htm


adding high-compression pistons/internals, head work, throttle body, intake manifold, etc MAY get you around 265HP at the crank. i know of only 1 that made reliable high power as N/A...

http://xcceleration.com/imp-gallery-rs.htm


XXYYZZ motorsport had one that made near 300HP at the crank, but ran like crap and blew up.
Great sound.
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Old 06-25-2017, 04:32 PM   #423
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Quote:
Originally Posted by terrainasaurus View Post
Great sound.
Thanks for these links, Terrainasaurus... Still unsure about the route I'm gonna take... I may just end up finding a late model sti engine at a junkyard and putting it on an engine stand, take it all the way down to the bearings and upgrade everything a little and see what I can do. Either way, I can see sinking $8k to $10k into the engine and then dropping it back into my OBS platform and enjoying my sleeper ***128527;
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Old 06-25-2017, 06:30 PM   #424
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Quote:
Originally Posted by ScooBear View Post
Thanks for these links, Terrainasaurus... Still unsure about the route I'm gonna take... I may just end up finding a late model sti engine at a junkyard and putting it on an engine stand, take it all the way down to the bearings and upgrade everything a little and see what I can do. Either way, I can see sinking $8k to $10k into the engine and then dropping it back into my OBS platform and enjoying my sleeper ***128527;
This is exactly what I'm thinking.

Well have to get some OB-STI or OBS-T badges made
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Old 06-25-2017, 07:58 PM   #425
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Recently I've been debating whether or not to go TWE headers for full n/a, or get wrx/sti EL headers with a custom catback and be able to swap them onto an ej257 to take the sti swap route.
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