Mine is an IHI VF-30, it's got a .63 a/r, six bladed wheel and flows a helluva lot more than the itty bitty stocker...Here's why:
The Turbo, was purchased through a local guy for around $600 locally in Salt Lake and came with an internal wastegate.
And installed with a full 3" custom built turboback exhaust with a flexpipe Flowmaster muffler:
Manual Boost Controller controlling it all Mounted on the stock BPV connector pipe. Got it from a great seller off Ebay,
Turbo XS Blow Off Valve neatly tucked under, available from www.TurboXS.com
And also on Ebay.com
(with my drag tires)
Before I start it should be said that this is how I did it, and it was done on a well-maintained, mechanically sound motor utilizing all stock components unless otherwise noted. All modifications are at your own risk and your experience may vary, this is simply meant as a guide.
Putting the turbo in is acutally fairly un-involved. Biggest issues are the flanges for the stock manifold and downpipe and building the downpipe itself. For us the process was easy, make a nice trace of the shape of the flange needed to match up to the turbo's flange with all the correct opening and bolt holes. Then take the trace to a local metal working shop, in my case Wasach Steel and have it either plasma cut or water cut in the same thickness as the flange your connecting it to. We had it water cut, as it provides very nice edges. Of course if you're good you can cut it yourself and drill out the holes. IF you're either really good with a torch and/or a plasma cutter.
When they are done, you're ready to weld the turbo inlet flange to the stock manifold. Of course your stock turbo is off as well as the studs going into the manifold. Again, you can either have a shop do this or if you're decent with a MIG welder do it yourself. I'd recommend beveling the edges and using Argon Gas. This helps you get a stronger weld with more material that won't crack. I've had my whole manifold and turbo glowing from lots of boosting and not experienced one crack. Nor have any of the other four we've put together in this exact fasion.
Next is attaching the turbo to the flange. You'll of course need gaskets for your new flange and for the downpipe flange. These can be had directly from a Subaru Dealership or from various online places such as www.SubyDude.com
You'll want to use some fairly high grade hardware for attaching the flange to cope with the heat and vibration. To start we tapped the manifold flange for threads and simply used a bolt screwed into that. We found that was not enough as the bolts, through heat and vibration could back out, causing a serious exhaust leak, pre-turbo causing drop in boost preassure. And it burns up your gasket. So, next a through-bolt was set up with a longer bolt
and a a locking nut as can be seen in the in-car shots. Be careful getting the bolts tightened as you want them to be very even. I recomment tightening the front two reasonably snug first and then the rear. If not, the large gap between the two bolts on the front can develop a leak. A third option is to use studs in the manifold flange. Once screwed in tight weld the tops of them and use a lock washer along with a suitably sized nut and tighten to around 25ft-lbs Of course your other option is to completely weld the turbine housing to the flange/manifild as seen here:
Benefits: IT WON'T LEAK!! EVAR!! Meaning you'll never have to take the turbo completely out, as well as the radiator, manifold and all the other things in the way, EVAR!!
Drawbacks: If you ever need to replace the turbo bearings or it blows, you'll have to take the whole manifold out (easier if you do) and simply take the turbo apart while attached to the manifold. There's a V-Band clamp that you can see as the shiny piece of metal between the mid-section and turbine housing. And if you ever want to change your turbo you'll have to get a new maniold which you would have to anyway, unless you WANT to cut the flange off you just welded on
Next comes the downpipe and exhaust.. Unfortunately to make the whole turbo fit, unless you run a considerably smaller downpipe, heavily fabricated you will probably have to remove your A/C and making it even easier also removing your Power Steering. Although it could be done with your A/C but it would probably require a custom manifold to move it over a bit. You'll need more high grade bolts/nuts to mount it up as well as the appropriate gasket from the site listed above. If you have the ability to build it yourself go for it, I recommend a full 3" turbo back with a nice free-flow system after that. If you can't do it yourself, hope you somebody who can, or a good exhaust shop.
After that connection of everything else is rather simple. The oil return line needed a bit of trimming but otherwise worked fine. I used my own coolant hoses and the stock oil supply line. The coolant hoses were considerably longer and I looped them around the turbo inlet piping which you can see just to the right of the compressor housing as two red hoses. The stock intake piping, as well as the stock outlet piping fit up just fine.
The Blow Off Valve. This is an excellent upgrade with this bigger turbo. The stock BPV may not be able to effectively bypass the boost without causing some compressor surge (compressor surge is bad, it ruins turbos) Almost any GOOD BOV will do as long as it is rated to work with the PSI range you plan on running. Of course using an aftermarket BOV/BPV will require blocking off of at least one ofthe stock BPV's ports in the plastic charge pipe and the turbo inlet tube. I simply made a matched plate along with RTV and bolted it on over the stock BPV's flange on the plastic pipe. Your other option is to simply replace the whole pipe with a similarly sized metal/plastic one. As for the hole in the inlet side, I used a stubby bolt that fit snugly in, and a hose clamp.
I recommend something sized close to the Turbo XS Type H. It comes in a few different varieties including a BPV version if you want to keep it quiet. as well as the RFL (Really Frucking Loud) version. Of cours there are many brands which would work fine as well, Greddy, HKS, TurboSmart, ect. Just make sure it's rated for the bigger turbo!. I mounted mine on the metal charge pipe between the intercooler and throttle body as seen here:
I recommend this location over the stock location as it prevents the air in the charge pipes and intercooler from having to travel backwards, and then reversing direction again when throttle is re- applied. Also it prevents charged preassure from backing up against your throttle body witch will help keep your TB Boot on since it sometimes has a tendancy to back off. I simply used a universal adapter, cut a hole and welded it in place. The BOV fits on over that. Don't forget to connect the top nipple to a vacuum source