Turbo Upgrade and Fabrication on the WRX


Hello everyone. This post is definitely off topic from my art world but being a believer that art transcends physical expression for visual interpretation into other domains, I figured that a project I did on my car which included a lot of custom design and fabrication fits the bill of art.

In this project I did a turbo upgrade on my 2008 Subaru WRX from the wimpy stock td-04 to the slightly bigger vf-39 that comes on an STI. I also designed and built a custom Water to Air Intercooler system because it was an affordable and complex way to cool off the extra heat in the intake.

The project took a few weeks of research and preparation and several days of fabrication before the turbo swap. The car is a daily driver and I do not have a shop so this was done in my (gravel) driveway. The main portion of the install took four brutal days of straight work. I’m covered in burns and cuts and bruises all over but in the end it’s well worth it! I even had enough time to put an off the shelf map (an 08 vf52 map) and make changes to it for my specific vehicle and make sure I’m running safe with no knocking.

It all began with the turbo ( a used VF-39 I got a great deal on ). Almost immediately after getting it, I ripped it apart and had it on the lathe to do a port and polish on the inlet/outlet of the compressor housing.

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I also immediately ordered a rebuild kit and rebuilt all the seals and bearings. But this post isn’t about rebuilding a turbo. Let’s get dirty.

The rest of the system has three major parts. There’s the Water to Air Intercooler, the Heat Exchanger (essentially a radiator) and a Pump/Resevoir to circulate the coolant. Because I started out with unnamed brand stuff this would be a total custom job with a lot of fabrication and modification to essentially all parts.

The Water to Air Intercooler (~$78.99)

I started with the Intercooler and figuring out a way to make it work with my new turbo and intake manifold. Here’s a dirty fit up job. notice the rock holding it in place… and the thing is HUGE (it barely fits)… and unfortunately being a cheap unit, the end caps are thick cast aluminum which is very heavy. On the flip side it’s 6061 which welds very nicely.

Ebay Parthttp://www.ebay.com/itm/800-HPS-X-LARGE-BAR-PLATE-LIQUID-WATER-TO-AIR-ALUMINUM-INTERCOOLER-16-5-X13X4-5-/151041847132?hash=item232acbaf5c:g:GesAAOSwv9hW42Fu&vxp=mtr


It also has huge 3.5″ inlet and outlet. The VF-39 outlet is just under 2″ and the throttle body on the car is 2.75″. I definitely did not want to have a ton of silicone angles and reducers under my hood so I will cut those off and fabricate new ones. But for now I had to deal with some brackets for mounting it (please note I later modified the right side bracket and had to completely get rid of the left side one which I used to mount the pump instead.

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Next up is the turbo side inlet. I originally was going to clock the turbo to point to the left (toward the wheel well) and having a wide U bend for the piping but in the very end decided to move it to cut on complexity and tubing length. I’ll show you those pictures later.

I started out with 2″ – 6061 Aluminum Tube – 1/8″ thickness. I trued it up and turned it on my wood lathe with special tools (I have a couple lathe tools I modified to be able to turn plastic which tends to grab with normal lathe tools. They work great for mild aluminum hand turning). Yes, it’s possible to freehand turn metal on a wood lathe. It takes longer and the end result requires a lot of sanding and finishing but it works great for quick, one off parts. I gave it a polish after sanding through all the sandpaper grades.
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I then chopped the stupid 3.5″ inlet/outlets and cut 1/8″ thick aluminum sheet to cover the holes so I can use my couplers instead. Now I realize that adding flat areas can produce turbulence and uneven airflow but it will do just fine in our application. If you think that’s bad, I used a chop saw with a fine toothed blade to cut the damn things off. Off camera I tacked the plates on, mounted the Intercooler in the engine bay and cut both the new inlet and a piece of pipe for the outlet where I wanted them.

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Because the original fitting was going almost straight to the left (the pipe was flat on the cover plate) I used my CNC Mill/Router to cut a perfect hole in the inlet cover plate. I then welded the inlet to the cover plate and welded both to the Intercooler.

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Nice fit. My welds are still pretty ugly but I got a LOT of very good practice on this project since my previous learning was mostly on scrap. By the way I learned TIG welding from scratch with no training and went straight into A/C welding on aluminum (the guys at the welding shop thought I was crazy but f**k them because I did it!).

The outlet was a similar process except I cut the hole on the bandsaw (I cut through the edge since it was going to be consumed in welding anyway). Because the metal was so thin I made a welding jig to hold it flat from 80-20 (I could have tacked it to the intercooler but I went in and rounded off the edges on the back side after welding).

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Looking good! There’s the Intercooler and two brackets to hold it.

Next up I needed to mount the Heat Exchanger in the front. Because it looks like an intercooler I wanted to show it off (naturally) but I noticed that on my 08 what appeared to be a black plastic parts that pops up down low was actually a part of the bumper cover so to show it off I would have to do a lot of cutting and that’s exactly what I did. The plastic was easy to cut with a freshly sharpened knife in direct sunlight (the temps were in the 80’s which made the plastic soft). I am also going to paint the bumper cover because the previous owner had it painted in a crappy shop so rock chips destroyed the thin paint. Anyway, here’s where I tore the car apart:
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The Water to Air Heat Exchanger (~$88.98)

Please Note: If you’re using this as a reference this is the point of no return. Mounting the heat exchanger required permanent and irreversible modification to the bumper cover and bumper beam. Even if I left the plastic grille in place I would have to remove parts of the bumper cover to make it fit.

The original heat exchanger was another relatively cheap part. It was much nicer than the Intercooler and was nice and light. However, it had several things that needed to be addressed.

Ebay Part: http://www.ebay.com/itm/FULL-ALUMINUM-BAR-PLATE-HEAT-EXCHANGER-WATER-LIQUID-TO-AIR-TURBO-INTERCOOLER-/391560369147?hash=item5b2ad113fb:g:ixAAAOSwmfhX2LCa&vxp=mtr

First, it came with holes for a drain valve and some other hole on the back. Because it would sit fairly low, I did not want a valve sticking out. Not to mention that if I needed to dump the fluid it would be just as easy to run water through the system and disconnect everything so I decided to just weld those shut…. because f**k those holes!


Another issue was the brackets it came with. There were four (two on top, two on bottom) which were held in place by two tacks… if you know anything about tack welds on aluminum is that they don’t hold so naturally I cut those right off and made some thick and beefy ones which I welded with a big bead on all sides. They are made from 1/4″ 6061 Alumium and there are two (one on top-left and one on top-right). They would be plenty to hold the unit in place. I also drilled the matching holes in the bumper beam to mach and I cut slots so I could hold a nut with a wrench while I tightened from the other side. Don’t worry I put a few coats of paint on the holes to keep them from rusting.

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After a lot of cutting and fitting I present you, the Heat Exchanger! All Mounted up and very visible…


..and so are those horrible rock chips, those are visible too :(. I really need to paint my front.  I was definitely very satisfied at this point but also nervous because the next part of the project had to be done in one go (this car is a daily driver and I do use it). Gladly it all worked out or else I wouldn’t be posting on here.

Here’s all the crap I had to cut out to make it fit:


And before I started I used my new color laser printer to make a shwanky Subie Logo for the Intercooler. Subie Represent!



Now into the Grind! In one day I swapped the turbo, took off and put back the Up Pipe (I wanted to gut the Cat, but turned out mine had no Cat to begin with). Did more work on the Intercooler and started to run some hoses.

First the turbo was removed and all the hardware transferred over to the new one (by the way, it’s not quite a direct swap. turns out the coolant lines are a different distance apart on the VF39 so I had to separate the two attachments. Also, with how I clocked the turbo, the wastegate touched the outlet so I had to grind it down… turns that particular turbo is not easy to clock in whatever direction you want, there’s only a couple of possibilities).

TD-04 out… VF-39 in. And the two side by side for comparison.

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The following day dawned on me that because of how I ended up clocking the turbo, I could save a lot of complicated hose angles and couplers by simply relocating the inlet on the Intercooler. So I chopped it, made another coverplate and moved it to a much better position (for now I coupled it up with a straight hose but I’ll eventually replace with a slightly angled silicone coupling meant for the job). I also modified the bracket for the BOV (it’s simply too wide to even want to mount so I cut off the ends and drilled new holes to make it more manageable). And it’s starting to look really nice. On the outlet side, the new intercooler mates with the stock silicone coupler that went to the TMIC. On the left side it’s a single coupling to mate the turbo outlet to the Intercooler inlet.

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I was having a hard time getting the factory silicone hose from the throttle body to mate with my outlet so I added a small angled section to it and it fit like a charm.


Here’s some close up shots of the finished inlet/outlet.

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At this point the car ran and the air path was complete. I also added all the fittings and ran some of the hoses and was getting ready for installing the resevoir and pump.

The Resevoir ($11.00)

This part is a little ghetto but I’m very much pleased to have pulled it off for under $20. I was going to spend 50 bucks on just alumiunum and welding up my own resevoir but instead I got a 2.5gal kerosine can that fits in in front of the fender perfectly! I was also running out of time so for now I strapped in in with a ratchet strap. Shockingly it’s holding it so tight and stable that I may use something similar as a permanent solution *but the bright orange strap looks hideous*.



The Pump ($49.99 + Shipping)


I finished running all the hoses and hooked up the pump. I also primed the system with some water and filled the resevoir with 50/50 Water / Coolant Concentrate mix. I actually used the bracket that I had to ditch from the intake side of the Intercooler to mount the pump. For now (I’ll have to come up with a better way to do this) the pump power wire runs inside the cab and is essentially hooked up to the cigarette lighter power to get power upon ignition).

And there you have it! The system works great and turned out better than I could have imagined. I will add some gauges to measure the air before it goes into the turbo and after it’s cooled off by the intercooler. I can tell you that after heavy driving while tuning the intercooler core was cool to the touch (that doesn’t mean it has effectively cooled the air tho).

I still have not finished building a box for my ram intake to get cooler air into the filter. My IAT temps run pretty hot and I’d like to get the temps colder even on top of the cooling I get from this setup.


Thanks for reading!