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Old 12-08-2017, 03:26 PM   #1
Scooby Newbie
Member#: 414827
Join Date: Mar 2015
Chapter/Region: RMIC
Location: Denver
2005 9-2X STi
Arctic Silver

Default envader's 2005 Saab 9-2X Aero - full STi swap!

What's up everyone! I've been a member of the Subaru community since February of 2015, when I picked up a 2015 WRX from Stivers in Decatur, GA. A few months ago, I swapped it out for my current vehicle: a 2005 Saab 9-2X Aero, with a full STi swap!

I picked up the car from another member back in early August. He threw a bearing in the original motor, and decided to swap in a longblock from a 2006 EJ257. For those of you that don't know (like me before I bought the car), this is a complicated, confusing, and time-consuming swap. The 2005 Aero is essentially a WRX wagon from a powertrain perspective, which means that it is powered by an EJ205 w/ 16-bit drive-by-cable ECU and throttle-body. The 2006 STi is obviously powered by the EJ257, and has the 32-bit drive-by-wire ECU and throttle-body. That means in order to retain the factory ECU (in order to keep the gauge cluster, reverse lights, etc. working), there are a number of things that set this apart from a regular "STi swap", such as retaining the WRX intake manifold and throttle body, customizing the WRX engine wiring harness, deleting the AVCS system, etc. It would have been MUCH, MUCH easier to do a hybrid build (EJ257 block w/ EJ205 heads) in my opinion, but that's what the previous owner decided to do, so oh well! The longblock had about 85k miles when installed.

In addition to the 2006 EJ257 longblock, the previous owner also swapped in a full 6-speed drivetrain that was originally on a 2007 STi: transmission, differentials, axles, hubs, etc. The STi drivetrain also had about 85k miles when swapped in. Also he added the legendary MAP DCCD controller - whoo!

Here are the build specs as it was when I picked up the vehicle:

-EJ257 longblock from 2006 STi
-Full 6-speed swap from 2007 STi
-SPT intake
-Perrin 2.4" silicone turbo inlet hose
-VF48 from a 2015 STi
-Cobb turbo heat shield
-2008 STi TMIC
-TGV deletes
-Stock fuel rails, lines, and FPR
-Stock fuel pump
-ID1000 injectors
-Cobb 3-port BCS
-Grimmspeed EWG uppipe w/ dump tube
-Tial MV-S
-Invidia catless DP
-Prodrive Axleback exhaust w/ stock mid-pipe
-KillerB Pick-up tube and windage tray
-Group N Motor, transmission, and pitch-stop mounts
-IAG Competition-series AOS
-MAP DCCD controller

After driving it back to Colorado, the first order of business was to get it to pass emissions. As it was, I failed with flying colors, so I needed a catted downpipe ASAP. Instead of just swapping out my catless for a catted aftermarket DP, or going back to stock DP, I opted to have one of the brand-new GESi 49-state legal catalytic converters welded in to my existing catless DP. I wasn't a huge fan of the EWG venting to atmosphere either, so I had the dump tube routed into the DP at the same time.

After owning the car for about a month, I took it up to see Harvey (aka TheBoostCreep) up in Longmont for a set of proper high-altitude tunes. I got it tuned on both 91 and E85, but my results were pretty disappointing w/ the mods that I had: 248whp on 91 @ 16psi, and 289whp on E85 @ 20psi. While tuning, Harvey mentioned that he was getting a lot of what he thought was false knock. At the time I just attributed it to ****ty quality gas and/or the turbo just not liking how the dump tube got routed..

About a month after I got the new tune, my dash lit up like a Christmas tree when I was driving home. Misfire codes, EVAP purge valve low voltage codes, etc. Fearing the worst, I asked a local shop to do a compression test for me... and ended up getting the bad news I was expecting. Low compression (~70psi) on cyl 2. Scheisse. Time for a new short block!
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Old 12-08-2017, 03:37 PM   #2
Scooby Newbie
Member#: 414827
Join Date: Mar 2015
Chapter/Region: RMIC
Location: Denver
2005 9-2X STi
Arctic Silver


I decided to go with a "stage 1" block from a local builder: Stock STi case halves w/ new nitrated crank shaft, stock STi rods w/ ARP Fasteners, King race rod and main bearnings, and Manley Platinum-series 8.2:1 forged pistons. With the ARP fasteners, the STi rods should be good to about 550whp.

While the car is down getting the new block, I decided to do some power upgrades because race car. Here is the final set-up I am going with:

-Built EJ257
-TurboXS short-ram intake
-FP 84mm hard turbo inlet
-FP Red w/ 8cm turbine housing (GT35R compressor wheel, rated at 65 lb/min)
-TGV deletes
-IAG v2 top feed fuel rails w/ dampeners
-Aeromotive FPR
-IAG braided fuel lines
-DW300c fuel pump
-EWG up-pipe routed to catted DP
-3" catback
-Stg2 Clutch

I'm hoping to make around 425whp on E85. I know my limiting factor is going to be the injectors, as well as the stock exhaust manifold, so those will be my next upgrades in a few months.

I should be picking it up in the next couple of weeks - review and thoughts coming shortly! Thanks for reading everyone.

Last edited by envader; 03-05-2018 at 03:23 PM.
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Old 03-05-2018, 03:07 PM   #3
Scooby Newbie
Member#: 414827
Join Date: Mar 2015
Chapter/Region: RMIC
Location: Denver
2005 9-2X STi
Arctic Silver


Little update.. finally got this thing back from the builder. Currently still breaking in the engine, but should be ready to turn the boost up by this weekend.

Wanted to go ahead and put the full mod list here.

EJ25 case halves bored to 100mm
Manley Platinum-series forged pistons (8.2:1)
OEM rods w/ ARP rod bolts
King Race rod/main bearings
New STi nitrated crankshaft
B25 heads w/ new valves, springs
OEM non-AVCS camshafts

SPT Intake
Forced Performance 84mm Turbo Inlet
Forced Performance RED turbo (w/ 8cm turbine housing)
TurboXS Front-Mount Intercooler
GoFastBits Respons Hybrid BOV
Cobb 3-port BCS
OEM drive-by-wire throttle body
OEM intake manifold (top feed)
TGV Deletes
AEM wideband sensor
IAG MAP sensor adapter
AEM 3.5bar MAP sensor

Injector Dynamics ID1000 injectors
IAG v2 Top-Feed Fuel Rails w/ dampers
IAG braided fuel lines
Aeromotive A1000 fuel pressure regulator
Deatschworks DW300c fuel pump

IAG Competition series air-oil separator
Mishimoto Performance aluminum radiator
KillerB oil pickup tube
KillerB windage tray
Cobb relocated coolant reservoir
Cobb turbo heat shield

Stock exhaust manifold
Grimmspeed EWG uppipe
Tial MV-S 38mm EWG w/ dump tube routed to downpipe
Invidia bellmouth downpipe
Vibrant GESi UHO-series catalytic converter
3" midpipe (unknown brand)
ProDrive axle-back

6-puck clutch (unknown brand)
2007 long-ratio STi 6-speed transmission
2007 STi DCCD
MAP DCCD controller
2007 STi front and rear axles
2007 STi driveshaft
2006 STi R180 rear differential (clutch-type)
2007 STi 5x114.3 hubs, knuckles, and bearings

2007 STi front and rear gold Brembos
StopTech Powerslot front and rear rotors
StopTech Sport brake pads
STi front and rear strut assemblies
OEM sway bars

OEM STi BBS 5x114.3 17x8 +53
Continental ExtremeContact DWS 235/45ZR17

Last edited by envader; 03-05-2018 at 08:55 PM.
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Old 03-11-2018, 12:45 PM   #4
Scooby Specialist
Member#: 110078
Join Date: Mar 2006
Chapter/Region: Tri-State
Location: Long Island N.Y.
05 Saabaru JDM STi
Black Ver 7 18G 6sp RA

Default envader's 2005 Saab 9-2X Aero - full STi swap!

A ej207 motor would’ve been a simple swap and could have kept avcs, good luck with the ej257. Let’s see the dyno graph, curious to see the power curve without avcs on a 2.5l.
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