Legacy Turbo FAQ

By Dave

Given the present number of Legacy Turbos available over the last year, due mostly to the release of the WRX in early 2001, mailing lists and bulletin boards have seen a noticeable influx of new owners. These owners are finding their cars enjoyable, but most have some very common questions. This FAQ was developed to help resolve any of the common problems with the Legacy Turbo.

Version 1.0 compiled and published April 26th, 2002.
Version 1.1 edited on October 6th, 2004.


Q: What turbo does the Legacy Turbo have?

A: The turbo is made by IHI, and is either the RHB5 or RHB52 model. It's the same turbo that was used on the Japanese Legacy, but the compressor outlet points towards the hood instead of directly at the intake manifold.

Q: What is the maximum boost I can run on my Turbo before hitting the fuel cut?

A: 13 PSI is the limit that can be run without hitting the rev limiter, and can be run safely without an intercooler if the fuel system is working properly.

Q: What is the maximum revs i can run before the fuel cut?

A: Most Turbos will stop at around 6700RPM, but the valvetrain has been rumoured to be stable at over 7000.

Q: Why didn't the Turbo have an intercooler?

A: The missing intercooler question is commonly asked, and we're not exactly sure why they deleted it from the US model. It's probably due to fuel requirements, transmission strength and that there wasn't reason enough to make it 200hp at the time. Instead, they made a unique engine, with a unique turbo housing and cooling system. Go figure.

Q: What intercoolers can I put on? Will the WRX one fit?

A: The stock Japanese Air-Water can be fit on, but it requires a pump, radiators and custom fabrication for the turbo outlet. It is not a bolt-on addition. The new WRX intercooler is too deep, e.g. it will not fit between the throttle body and firewall on the Legacy without modification. The early WRX "slanted" intercoolers fit, but not without significant work.

Q: Are there any other intercoolers that fit better?

A: The Saab 900 had a small side-mount intercooler that fits relatively well with a bit of custom work. The Suzuki Sprint Turbo had a smallish intercooler that has been used also. The Mitsubishi Eclipse intercooler could possibly be used, as a top or side-mount. Many turbo kits for the RS and Impreza are custom built.

Q: Can I put a WRX Turbo on my Turbo?

A: You should be able to bolt on the turbo, the up and downpipe connections should be perfectly matched. The problem is the inlet and outlet on the compressor side. These would have to have custom pipes made to work.

Q: What's this black thing on top of my turbo?

A: We like to call it a Chimney, and that's probably a very accurate description of what it actually does. At low speeds and idle, heat is kept inside the chimney and vented through a baffle under the hoodscoop. At speed, air might be forced down to the turbo, but not very much.

Q: What size are my fuel injectors?

A: 360cc

Q: Is my 2.2L engine the same as in the non-turbo models?

A: No, the engine displacement is the same, but the engine is very different. In fact, it's unique to the US market to the best of our knowledge. The block is of a closed-deck design, ideal for high-boost applications. The crank and rods are forged, while the pistons are cast. This combination should be good for at least 300hp with proper engine management without needing to replace any internals.

Q: Can I put the DOHC Impreza heads on my EJ22T?

A: The heads will indeed fit, but there are several problems with it. The EJ25 uses a larger bore, and using these heads on a smaller bore engine will create an overlapped "squish" area. The coolant passages don't quite line up, the intake manifold would have to be replaced…you get the point. A port and polish on the existing heads and perhaps an extrudehone on the intake manifold would net a very substantial gain over any swap available.

Q: My sunroof leaks, how can I make it stop?

A: There are four drain holes that eventually get clogged up and need to be cleared, but it involves removing the headliner to gain access to them. Another, more common solution to the problem is to scrape away the black sealant around the sunroof rails and replace it with a fresh bead.

Q: My gas gauge never goes to full, is this common?

A: Yes, this is common. If the tank is filled to full and run down consistently, it's been known to help the gauge get back to a more normal reading. The tank is approximately 16 gallons.

Q: Can I put WRX, Forester or Outback wheels on my Turbo?

A: As a general rule, any 15" or larger Subaru wheel with the 5 lug pattern will interchange, with the exception of the SVX, which uses a different patten.

Q: Can i put WRX, Outback or any bigger OE Subaru brakes on my Turbo?

A: Any Legacy or Impreza brakes will bolt onto the turbo, front or rear. The WRX 11.4" are a popular upgrade from the 10.9" stock units. Any larger upgrades meant for the WRX will also bolt on.

Q: I get a rumbling noise when I accelerate at low speeds with the wheels turned, what is that?

A: That is most likely what is called "Torque Bind". It happens when the solenoids in the rear section of the transmission fail or are failing, causing the AWD system to not work properly. This is usually an expensive repair, between $500-1000. It's hit and miss on the problem up until 1997, when the problem was fixed. Newer revisions also had problems with wear in that same area of the case, necessitating replacement of that section of the case.

Q: Can I just put in a Legacy or Impreza 5-speed transmission to replace my old, failing automatic?

A; theoretically, any Legacy or Impreza transmission will bolt up to the EJ22T, but the clutch type, flywheel type and pressure plate must be taken into consideration. The torque delivered by the EJ22T is more than any N/A Subaru engine except for the 3.3 H6 in the SVX. The Legacy Turbo 5MT was taken from the Japanese market directly and is considerably stronger than any other 5MT available, save for the WRX, which shares the same transmission.

Q: I need to replace my clutch, does anyone make an aftermarket one?

A: Many companies make compatible clutches. ACT, Clutchmasters, Exedy and JUN make very good ones with higher rate pressure plates. STI makes an upgraded Group N clutch that is comprable to most of the aftermarket upgrades. The Legacy Turbo can basically use any year WRX clutch AND flywheel.

Q: Does anyone make a lightweight flywheel.

A: Exedy, Jun and Fidanza, as well as other companies, make compatible flywheels. As in the case of the clutch, any WRX part will fit.

Q: Does my Turbo have a Limited Slip Differential?

A: As a rule of thumb, only the early 91 models were definitely known to have them. It might have been an option up to 94, but very rare. The easiest way is to look on the differential itself for a tag that denotes it as LSD. Another way is to jack the back off the ground and turn one wheel. If the wheels turn in the same direction, it is equipped with an LSD. If they rotate in opposite directions, the differential is open.

Q: What is the Final Drive ratio of my Turbo?

A: 3.90 was the ratio of both the automatic and manual transmissions between 1991 and 1994.

Q: Can I put newer Legacy or Impreza suspension parts on my Turbo?

A: Yes and no. The newer Legacy parts are universally interchangeable, up to 99 at least. All struts, sway bars, endlinks and strut tower braces will fit the older Legacies in general. The only Impreza part that does not fit for sure is the rear swaybar. The Legacy version makes accommodation for the large spare tire well, whereas the Impreza one is much smaller. All coilovers from the major brands, TEIN, CUSCO, DMS, etc, should fit fine.

Q: I want to replace my shifter with a short throw version, which ones fit?

A: The early Legacy models used a slightly different shifter assembly than what is currently used on the Legacy and Impreza. The popular short shifters from Cobb and Kartboy will not fit due to a different width of the shaft. The best overall solution for a better shifter is to purchase the entire STI/SPT shifter assembly, plus the linkage that connects it to the transmission. This is a very good setup and makes for nice, quick, firm shifts. Other options include used WRX shifters or any assembly from a model with a hydraulic clutch. Upgrading the shifter becomes possible, and usually costs less than the STI parts.

Q: I want to get more boost, what are the best boost controllers for doing this right?

A: There are two types of boost controllers, Manual and Electronic. The manual varieties trick the wastegate into staying closed at higher boost pressures by bleeding off pressure through a relatively primitive bleed valve. Hallman, TurboXS and Joe P make quality versions of these controllers for less than $100. Electronic controllers use microprocessor controlled solenoids to regulate pressure, usually more accurately than the manual versions. Apez-I, Greddy and Blitz made the more popular versions of these. Prices range from $300-600. Electronic controllers usually integrate boost gauges as well as a multitude of other features.

Q: My transmission is hard to shift from gear to gear. If I pause for a moment, it seems to go in fine. What is this?

A: There are gear syncromeshes that allow for smooth, quick shifting between gears. Over time these wear out, sometimes prematurely as an effect of low fluid or abuse. Try replacing the fluid with Redline MTL or BG Syncroshift.

Q: My automatic sometimes won't shift very well and dwells before finally going into the next gear. What causes this and what can I do about it?

A: Usually this transmission should shift quickly from one gear to the next, but when the transmission is wearing out, it will hesitate to upshift. Try getting the transmission fluid flushed out. This could also be a sign that the braking bands are loose and need adjustment. Most transmission shops that can work on Subarus should be able to adjust this, as will the dealership. Transmission rebuilds aren't inexpensive, plan on $2000-3000 for a quality rebuild. Transmission exchange shops are the best bet, as they charge a flat rate for the transmission and the turnaround usually consists of the removal and reinstallation time. A swap for a 5MT is also a possibility, but isn't really cheaper and should be done by a competent mechanic.

Q: What is the difference between the automatic and manual transmission AWD systems?

A: As a rule of thumb, the Automatic is a 90/10 front/rear split while driving, but is apparently 50/50 in 1st and 2nd gears. This is variable based on wheelspin and is controlled within the transmission. The Manual uses a Viscous Coupling center differential to divert power back and forth. Normally the 5MT is a 50/50 split, but is dynamic based on conditions.

Q: I just installed a boost gauge and no matter how hard I push the car, I never get above 7PSI. I thought the factory boost was closer to 9. Did I connect the gauge wrong?

A: The factory boost control is very simple, and uses a system similar to the manual boost controller in that it simply bleeds off pressure. These mechanisms fail, and when they do, the wastegate's default opening pressure will limit the amount of boost available. This value is usually between 6-7PSI. A replacement factory solenoid is not the best solution. A basic manual boost controller is the simplest solution to getting back your factory boost levels and more.

Q: When i accelerate hard, the car seems to jerk and hesitate. What causes this?

A: The Boost Control Solenoid is the culprit. It's located on the passenger side strut tower, and is a reddish color. It's is replaceable, but most prefer to upgrade to a simple and effective manual boost controller for less than half the price of a new replacement from Subaru.

Q: I haven't tuned up my Legacy in a long time, what are the best items to check and replace?

A: Spark plugs, plug wires, fuel filter and air filter are the standards, and will do nicely for the turbo. The Oxygen Sensor might need to be replaced at over 100k miles, if it has never been replaced.

Q: When I go over bumps, the steering wheels shimmies back and forth and I hear a terrible clunking, what can I do to fix this?

A: Chances are your front swaybar endlinks are worn out and need to be replaced.