This write-up is done to detail the process of adding a Legacy Turbo to the MY00+ 2.5RS while retaining the EJ25 engine. In theory, this process will also work for any year WRX components including the new MY02 WRX with minor variations.

I was in the process of doing this, so this is all from first-hand experience. However, I dropped the project due to financial concerns so this is as developed as this page will probably get. I do not guarantee that this will work on you car, but it should serve as a good baseline. Please be aware that if you force more air into the engine (via turbocharger) you must also add in more fuel. You cannot just bolt a turbo onto a naturally aspirated car and expect its fueling needs to be met.

If you do have questions you can email me or try searching for your answers on Nasioc.com .

There are pics for a number of the parts. For most of them, simply click on the thumbnail to see a larger image.

1991-94 Legacy Turbo (Sport Sedan or Touring Wagon) Adaptation

For a basic run-down of what is required to go through a turbo install, please visit ImprezaRS.com and take a look at the JC Sports IHI Turbo Kit installation instructions written up by JC Sports and Larry Ganz. Many of the steps can be applied to any turbo install.

Blaster88 has done a brief writeup which details the various points of his experiences of this install.

Subachad has also done a decent writeup regarding basic functions of the turbo system as well as great tips for building your own kit. You can also find a basic parts list for the turbo kit. His website is here.

Parts List -- Here is my current parts list. It gives the part, part number where applicable, the approximate price, and the location the part can be found. This will give you a good idea of how much it will cost to go the same route I have done. The list is broken down into what is absolutely needed, optional parts I chose to use, and extra go-fast goodies which I dream of and may one day own.

I located the main turbo parts by doing a search for 1991-1994 Legacies on CoPartFinder. You can try these websites: Adelaide, Aaron's Auto, Octagon Auto, Parts Plus, F&S Auto Parts, Findpart.com, MyPartShop.com, or Fitz Auto. Or Outback Motorsports may be reached by speaking with Steve or John at (714) 994-5222. The parts are getting rare, so good luck in locating them. I detail any possible substitions in the sections below.

Legacy Turbo, IHI RHB52 -- The particular turbo I received was from a '93 Legacy Turbo Sport Sedan with 74,000 miles. On initial inspection, the turbo looked to be of incredible condition, but after removing the compressor housing, the play in the shaft got excessive. If you have any doubt, rebuild the turbo. Turbo City is a good source for rebuild kits. You can also try any authorized IHI turbo shop. The DIY kits cost $130 or a shop will rebuild it for you for about $300 (which usually includes balancing). The seal plate will be a bear to get off, and you need to soak it in WD-40 to disolve the silicone holding it together. There were also some screws that were held in by loctite and I had to use an impact driver to get them out. The turbo was $250 from John's Import Auto Wrecking. These pics show the turbo and internal wastegate. The oil and coolant lines have been removed, but you can see the two ports on the side where the coolant lines run, as well as the oil inlet ports on the top. You can substitute the turbo with just about any of the IHI line as well as the WRX Mitsubishi TD04L. I plan on purchasing an IHI VF22 ball-bearing varient eventually.

Exhaust Manifolds and Crossover Pipe -- This is the new routing for the exhaust. It is more confined to allow for the outlet to the turbo uppipe. It appears to be the exact same part as found on the pre MY01 JDM WRX. The manifolds should also be the same as the new-age WRX manifolds. Cost was $175 from John's Import Auto Wrecking. Note the difference between the naturally aspirated (NA) headers (left) and the new turbo exhaust manifolds (right):

The NA headers actually come off the exhaust ports on the heads and bend towards the back of the car. They go underneath the crossmember and bolt up to the cat pipe. This is close to an equal length header, but has a nasty bend at the collector. The turbo exhaust manifolds are made of cast iron, weigh 45lbs, and they go from the heads and bend towards the front of the car. This forces the waterpump and thermostat housing change explained later on. The location of the up-pipe flange is right inline with where the crossmember is located, so this forces the turbo crossmember change. My reasons for all this work were that I liked the idea of manifolds designed for a turbo as well as later being able to upgrade to the tubular style Cusco piece shown below. By going this route, it leaves the project open to WRX turbo upgrades because it will share the same system. Just keep in mind that if you buy aftermarket headers, they cannot include the up-pipe section because the up-pipe needs to be pushed away from the manifold by 20mm (I explain later).

Turbo Up-pipe -- With the factory heat shielding on, the Legacy up-pipe does not come close to fitting. It hits a rectangular protrusion off the head. By removing the heat shielding, the up-pipe will almost bolt up. Adamrs mentioned that he was able to bolt the up-pipe on without a spacer, but later added a spacer for extra clearance. For me, the flex pipe hit the camshaft plug housing on the back of the head. I think dremel work or removal of the flex pipe will allow this to fit (it is really close). You can see the conflicts I found in the picture series to follow:

Blaster88 located some exhaust flanges and created a 3/4" spacer between the up-pipe and the exhaust manifold; this provided enough clearance away from the head to allow the up-pipe to bolt in even with the factory heat shields intact. The DOHC MY98 Imprezas should not have this clearance problem.

My solution was to have a 20mm spacer machined for a good, leak-proof fit. The cost was $70 at a local machine shop. At the same time, I also had them port out the openings of the up-pipe due to some really slopping welds.

Fuel Rail -- The next problem deals with the fuel pressure regulator (FPR) and where its mounted on the fuel rail. On a factory Legacy turbo, the FPR is located much lower and closer to the heads. On the RS, the FPR actually sits right where the inlet on the turbo goes. A relocation is necessary. There are a couple options: you can bend the fuel rail about 45 degrees out away from the head in order to get the clearance needed, cut the rail and relocate the FPR with some fuel hose, or the passenger and driver's side fuel rails can be switched. I did a combination of both by switching rails and then cutting the FPR off the now driver's side rail. I did this to convert my fuel system from a series feed to a parallel feed (documented at Ravensblade). If you cut the fuel rail, you will need to source some 1/2" fuel line, which is not a common thing. I would recommend converting your rail to a parallel feed too. While it is a difficult and time consuming process, it removes most of the risk of #3 cylinder running lean. It supposedly adds an additional 8psi of fuel pressure to the #3 injector and I personally noticed my fuel pressure drop a couple psi, so more fuel is being used. You can just purchase the Super Jammy Fuel Rails from Vishnu and reduce the difficulty considerably. You can see how the FPR gets in the way:

Turbo Engine Crossmember -- The new exhaust manifolds need to run in front of, and over the crossmember. The NA crossmember doesn't allow this so a manifold designed for the turbo manifolds must be used. Cost was $150 from John's Import Auto Wrecking. My install time for this was actually about 4 hours, taking it slow and easy. My second time doing this (see below) actually only took me about 1 hour. Warning! Do not attempt this install unless you are ready to complete your entire turbo project. I found this out the hard way. The NA headers will NOT bolt up with the turbo crossmember in place. The part of the crossmember that drops down for the turbo up-pipe conflicts with the NA headers. Here is a brief overview of the install quoted from Imprezer (I-Club); I have gone through and revised the install instructions with my own experiences: "Put it on jack stands [the best place for the jack stands are under the rear mount for the front control arms]. [First, you must unbolt the catalytic converter pipe from the support braket and remove the 6 14mm bolts holding the exhaust headers to the block. Then, unbolt the headers from the cat pipe with a 14mm rachet and wrench; be careful with the O2 sensors, don't want to pull them out of their wiring harness]Unbolt the engine mounts from the x-member [with 14mm deep socket]. Remove the pitching rod [we were actually able to do this install without removing this pitching rod; the part he is referring to is a dog-bone shaped plastic piece located underneath the airbox and just above the transmission]. Jack up the engine and bit. Maybe an 1" or so [just enough for both engine mount bolts to clear the crossmember]. Remove the [cotter] pin from where the steering rack [arm] attaches to each hub. Remove that 19mm castlenut. Wack the top of the steering rack arm bolt and it will drop out of the hub [we are basically unattaching the steering rack from the wheels so we can remove the rack]. [Remove the front sway bar at the endlinks and at the mounting points (12mm)] Unbolt the control arms from both the x-member [use 17mm rachet and wrench] and the unberbody, so that the only place they remain attached to is the hub [I actually found that if you have two people, you can leave the rear control arm mounts attached and just man handle the control arms out of the way. The rear control arm mounts are really torqued down too; we actually broke my 19mm socket trying to remove them, so they stayed bolted up in the rear]. Crawl under the car from the front drivers side. Find where the steering rack attaches to the steering column/shaft/pole [we are trying to locate the steering knuckle, the best way is to go above the engine compartment and locate where the steering column goes through the firewall. Remove the 2 12mm bolts and before sliding the joint off, mark how it was sittng there so that you won't have to realign your steering afterwards [this is a spline joint, so it is easily possible to get your steering wheel crooked; I did. You can work with this steering knuckle by just jacking up the car, so its not that critical]. Slide the joint off. Remove the power steering lines where they connect to the rack on the lower passenger side. Use 17mm and 14mm wrenches [slowly undo the nuts at equal amounts so you can remove both lines almost at the same time. You will get powersteering fluid everywhere as soon as the nut is undone. I pulled the lines up above the powersteering pump to prevent leaking]. Cover all of the lines so that nothing gets inside. [Remove the steering rack from the crossmember by removing the 4 14mm bolts.] Remove the 2 17mm bolts on each side where the x-member is attached to the body. Remove the old x-member and install the new one reversing the insructions....[Don't forget to check your power steering fluid and add if necessary while cycling the rack lock to lock]" A special thanks to Imprezer for that one. The dirty crossmember is the NA crossmember and the clean crossmember is the one that I received from the Legacy turbo. In the first pic, the front of the car would be in the lower left corner.

Turbo Waterpump -- On a stock, NA waterpump the thermostat outlet is on the bottom. Since the new Legacy exhaust manifolds bend towards the front of the engine ( as opposed to towards the back of the engine like the stock headers), it would interefere with the bottom mount thermostat. The new Legacy waterpump has the thermostat outlet on the front to enable clearance of the turbo manifolds. When you order, you must make sure that the thermostat outlet is on the front of the waterpump, not on the bottom. Most parts stores I went to didn't have a different part number listed for NA vs turbo waterpumps, so be sure to inspect it when you receive your order. I purchased mine from Parts America and the part number is WP878. Cost was $78.99. Be very very careful not to strip one of the 6 bolts. The torque is only about 13ft/lbs and my torque wrench didn't click in time. I ended up with one stripped waterpump bolt, though I do not have any coolant leaks. You will have to block off the top port on the waterpump, as it is unused in non-turbo EJ motors. I just used a brass fitting pushed into some heater hose. The pump on the left is the Legacy waterpump, and the pump on the right is my stock RS waterpump. Note the front mounted thermostat and the blocked off coolant port.

Turbo Thermostat Housing -- This must be replaced when changing out the waterpump. Since the thermostat location is being changed from the bottom of the waterpump to the front, the lower radiator hose angles are different. This is corrected by the use of the Legacy turbo thermostat housing. I picked mine up for about $15 from Japanese Auto Wrecking. To get the lower radiator hose to connect to the new waterpump, you can simply use your stock lower radiator hose. I also added a spring coil inside the hose to keep it from pinching. Might as well replace the thermostat while you are in there playing in the antifreeze. Cost was $20 with gasket at the local Subaru Dealer. Everywhere else has the thermostat as a special order part! Legacy Turbo thermostat housing is on the left, stock RS housing is on the right:

Turbo Oil Feed and Drain Lines -- These fittings allow you to tap into the oil source for the engine and run it through the turbo. The oil feed fitting pictured below is found at iSR for a price of and $34.95. The oil feed taps into the oil pressure sensor on the backside of the block and bolts onto the turbo oil inlet. It is the same location as what's detailed in the JC Sports IHI turbo kit instructions.

After doing a lot of research on the use of a banjo bolt for the oil return, I have decided against it. The draining abilities of the banjo bolt are substandard and I do not want improper oil drainage. A gravity fed oil drain will not work if there are any obstructions; in this case, it would be the oil in the oil pan. Instead, I am going to have my oil pan tapped above the oil level in the oil pan, then use a pressure fitting (screws on either side of oil pan and clamps the fitting together). The cost will be about $35 from Modern Garage. With some 5/8" high-temp braided oil line ($40), we can run the return. The proper, albeit expensive, alternative is to use Earl's Speed-Flex Series 600 Teflon Hose 9/16" AN -10 for $50.00. An Earl's Male Weld Fitting AN -10, P/N 967110, can be had for $5.11 from Baker Precision; and Earl's Swivel Seal Hose End, 45 deg, P/N 804510, for $26.70. An example of this oil pan tap is pictured below. Just about anything goes, just make sure you return line doesn't bend more than 45 degrees.

Coolant lines for the turbo are tapped in from a line behind the back of the block. The best source for the coolant is the heater core line. Trey Cobb suggested using a green heater core line (located on the back of the block) to feed the turbo and return the coolant to the heater core return line which goes back into the waterpump. This way, if your car starts overheating you can turn on your heater and it will cool your motor and turbo together. I think you can just tap into those lines with a couple fittings picked up at any local autoparts store.

click here for part 2