SUBERIOR | Subaru Specialties and more. Simpsonville SC

Josh’s EJ18 Turbo Build Project.

27 Jul

There are not a lot of articles detailing Turboing an EJ18 Pre OBDII Impreza so I will try to explain in as much detail as possible my build in hope it will help someone else’s project out in the future.

First off stock compression ratio is 9.5:1 – 9.7:1 so to make some leeway I added EJ22 Heads, and Cams. While I was in there I decided to do all preliminary maintenance and fix gaskets, seals, and checking for wear and tear. Before any project adding horse power to vehicle old enough to drink now is a great time to think about your supporting mods. Make sure all of your components are solid.

  • Does your transmission knock or whine? Better take care of that before put more power through the drivetrain.
  • Have you upgraded your fuel pump, injectors, and filter? Now would be a great time to sort that.
  • Are your brakes squealing? Best time to upgrade is when you have to do it anyway!

Once you have everything in order, now is time to start doing your budgeting and either going all in or slowly overtime acquiring your parts.

For my project I am going to outline main components there are plenty of threads on NASIOC to explain how to do your waterpump or replace your heads so I will spare you technical details outside of getting your car to make boost.

First off here is a parts list that so hungrily ate at my bank account like a fat man at a buffet.

Turbo and components

  • TD04E Turbo from a 2002 WRX.
  • 2002 Top Mount Intercooler.
  • M12 X 1.5mm Banjo and waterline kit (Volvo and Saab were my best bet)
  • 4AN 4 AN -4 to M10 x 1.5 Metric Straight Flare Male Fitting Adapter Hose / Line (for oil inlet port)
  • 2″ to 2″ 90 Degree Elbow 4-Ply Turbo/Intake/Intercooler Piping Silicone Coupler Hose+T-Clamp (Blue)
  • 2.25″ To 2.5″ 90 Degree Elbow Turbo/Intercooler/Intake Piping Coupler Reducer Silicone Hose (Red)
  • 2″ Straight steel piping for Y pipe modification. (have a bit of radiator hose for sealing is great for this too)
  • Ebay oil sandwich adapter oil return /feed line kit 10AN Return– 1/8th NPT & 4AN Fittings — Feed line.
  • 3/4″x3/4″X1/2″ Pex Shark Bite Tee X2
  • Heater core hose 1/2″ ID 8′ length
  • No name GFB Blow off valve clone
  • All gaskets and washers.
  • 20′ worth of vacuum line
  • Vacuum line T fittings


  • DCSports UEL Header
  • Invidia Uppipe
  • Invidia Downpipe (Modified with secondary bung for AFR Sensor)
  • 2002 WRX Midpipe
  • 2002 WRX Muffler
  • All new gaskets, studs, and bolts.


  • 2002-2003 WRX Crossmember (Make sure you are getting the turbo notched crossmember)
  • 2002-2003 WRX Swaybar

Custom fabricated parts

  • 2.5″ to 2.5″ OD 90° Mandrel bent custom intake piping.
  • Tig welded 10AN return bung on passenger side valve cover.
  • W bent AC line to clear TMIC Y pipe.
  • Spectre Vacuum line/sensor install kit


  • Innovate AFR Gauge with Bosch Wideband sensor
  • Equus Boost Gauge (O’reillys clearance special du jour!)
  • Dragon Oil Pressure Gauge


  • 12:1 FMU


Step one: Preparing the bay

Might as well get this out of the way if you still have your airbox you will need to switch to pod filter so add this to your list of parts as well as the silicone connectors and adapters for your MAF.

Once you have that eliminated time to work on getting your wiring out of the way and start tucking and routing everything. I disconnected the clip for the ECU harness from the intake manifold and neatly zip tied them behind the AC line near the fire wall.


Step two: Crossmember

As said not going to go into much detail on these parts but you will need to be aware that the swaybar linkage does differ and I had to change mine out with a 2002 WRX Swaybar. The powersteering pump however mounted perfectly into the 2002 xmember with little problems.


Step three: Exhaust and clearances

Install your header/manifold as you would normally but be aware that depending on the make of the header size may differ. I had to cut off the wiring loom support notches off my lower radiator fan shroud and relocate the fan harnesses up 6 inches to prevent wiring issues or scorched wires. I also had to cut a small lip from my transmission crossmember to allow for my downpipe to clear properly. Another clearance issue is with the 2002 TMIC I had to angle grind almost a full centimeter from the lip to allow for it to fit properly to the throttle body and unless you are using a 90s Legacy GT intercooler or a later 2000s model intercooler you will have to do the same. Remember measure, cut, and measure again. You can take away but you can’t add back after its gone.


Step four: Everything else

Take off your air intake removing your PCV/IACV vent lines and any vacuum lines. Once the intake is clear and out of the way take out your pitch mount and pull the AC line closer to you without kinking the line. Using an angle grinder cut away the lips off the V above the pitch mount and relocate your ignition module. Bend the upper lip under the hoods weather seal to allow for intercooler clearance. In my project I had to cut off 1/2″ from the intercooler outlet lip to allow for clearances as well. Test fit and measure and test fit again (repeat until you are driven to drink). When you are satisfied cut the 90° lip from your Y pipe and insert your 2″ piping setting this aside for later. Install your uppipe and mount the turbo once again for test fitting. At this point you will notice some clearance issues with your inlet piping to the turbo. I remedied this by using a 2.25″ to 2.5″ 90° elbow cutting to size to allow for the piping to mount. You will need your CAI or custom piping to install to your MAF at this point. Connect your piping and reinstall your PCV/IACV to your vacuum ports that are either drilled out and installed from a kit or come already welded into your CAI. Install elbow and bring back your intercooler and measure length from your pipe while using another 2″ to 2″ 90° elbow and cut to fit over the outlet of the turbo I took care of any extra gaps on the piping by sliding a piece of radiator hose and hammering it onto the pipe.

Install your valve cover with the 10AN port for oil return to the heads.

Now you need to cut your heater core lines. On my setup the lower pipe on the driver side was the inlet. I tested by removing the line previous to turboing the car and running quickly to test flow. Using your brass pex fittings tee in another hose to be installed to the inlet of the turbo repeat this process for the return line running to the lower outlet of the turbo.

At this point you should reinstall your pitch mount and route hoses and lines to clear your clutch fork.

Next drain your oil and add your sandwich filter adapter. Run your lines making sure not to kink anything on the feed line or return. Your return line should be screwed into the return port on the head.

Using a 3 inch silicone coupler install your TMIC. I did this by pushing the top end of the intercooler to the firewall then routing the Y pipe adapter to the turbo then sliding back into the silcone coupler. You may need to use a flathead to pull the coupler over the outlet. I also had best results using 4″ worm clamps and decoupling them sliding the metal notched in under the throttle body and then reattaching rather than having them on the coupler before hand (It will be cut smaller than you would think). Once you have your silicone elbow tightened down to the turbo and throttle body test and mount your blow off valve to make sure you will clear your hood.

(Side note: unless you are doing a Front mount setup I would advise getting the OBS or 2.5RS hood with scoops assuming you haven’t already.)

At this point you should have water/oil/air so next would your FMU. This is totally optional but I installed a 12:1 FMU running lines from the fuel rail and vacuum line to your choice on the intake manifold.

This should take care of most clearance issues on earlier 90s Imprezas for anyones custom turbo build. Sparing the details on running the exhaust and basic turbo lines you should be pretty well off to finish the project at this point. This post is to hopefully help anyone who has been running into the same issues I have and hopefully will answer some of the more detailed questions.

Next project I get to delve into is tuning an OBD1 setup via Aftermarket ECU or creative tweaking to the current. At the current time of this build the AFR reads a fairly steady range of 14.0-14.8 average AFR dipping down to 10 under full load at 8-10psi. I would like to thank my friends at Sexton’s Muffler Shop, Leslie’s Sheet Metal Works Inc, and Dexter for all the help with fabrication, and putting up with a million questions.

Here is the first startup of the motor.


Here is after all of the vacuum leaks, exhaust leaks, and small issues that happen after custom building your own setup were fixed.

Non boosted turned boosted #boost #imprezawagon #subaru #turbo #homebuilt

A video posted by matt islife (@yung_mattrick) on


For pictures visit the original post at here




The evolution of Symmetrical AWD

9 Sep

Some history and info on the Subaru boxer engine

9 Sep

More on the 22B, 1/424 ever made and one of only two in the U.S.

9 Sep

The rarest of rare Subaru’s

9 Sep


9 Sep

For those that haven’t, meet the Brumby.

9 Sep

Awesome R/C Subaru video!!

9 Sep

Check out this Legacy on Roadkill!!

9 Sep

Exciting Things In The Subaru World!

8 Sep

There has been a lot more talk about Subaru lately with all controversy and rumors surrounding the BRZ. But more interesting to enthusiasts like myself are the new model packages that could be in the near future. Subaru released a new concept Forester STI at a Japan auto show, yet another version of the Impreza and WRX have been seen in testing running around, and even the BRZ which was thought to be possibly getting the chopping block because of problems with the agreement with Toyota is rumored to be getting a proper STI package. Our rally team drivers are competing fiercely and bringing home a few wins along the way too. Keep your eye on Subaru this year, the game is changing in their favor.

these links connect you with a few articles that go along with this news!   Rally, Forester STIBRZ STI (concept), 2017 impreza/WRX   Enjoy!