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***Subaru Impreza WRX STI ~History and Facts...***

Discussion in 'Subaru' started by CLUTCHONE, May 4, 2006.


    CLUTCHONE Active Member

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    Apr 27, 2006
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    The Subaru Impreza WRX STI (often referred by auto-enthusiasts as simply STi; in 2006, the acronym had the 'I' capitalized; hence it is currently STI) is the highest trim in the Subaru Impreza line (excluding the limited edition special cars). Subaru uses the WRX as the basis for its World Rally car in the FIA World Rally Championship. Subaru created Subaru Tecnica International to handle its motorsports activities. After the company had grown, it was used to make highly-tuned high-performance versions of the Subaru Impreza WRX, a 4WD sportscar with a turbocharged flat-4 engine.

    GC chassis (1992 - 2000)

    There were 6 noted versions of the STi. The different versions were marketed with consecutive numbers. Another way to tell the version of a WRX STi was to look at the chassis code. All WRX STis have the beginning chassis code of GC8 then followed by a letter from A to G.

    Version I (1994) - GC8A/B: The first STi had 250 PS (184 kW) @6500 rpm and 31.5 kgf·m (309 N·m) @3500 rpm and weighed 1230 kg (2,710 lb). This version was the only version where the standard cars were taken at the end of the assembly line and replaced by STi parts. After this version, the standard STi was built alongside the WRX on the production lines.

    The WRX Type RA (Rally Applicant) STi produced 275 PS (202 kW) and 32.5 kgf·m (319 N·m) of torque. This version of the WRX STi was a stripped out car that had no sound-deadening, radio or air-conditioning. It came sparsely equipped as it was to be sold to racing teams that would throw out the cheap parts for racing parts. This version of the WRX came with a Driver Controlled Center Differential (DCCD). This device was an electromechanical differential that could lock the differential. This allows the amount of torque sent to the front and rear wheels vary from a split of 35/65 to 50/50. The DCCD would be beneficial to people who used it in various rally conditions.

    Version II (1995) - GC8C: The regular STi's engine output stood at 275 PS (202 kW) and 32.5 kgf·m (319 N·m) of torque. This was the year that STi started painting the exhaust manifolds red. The car weighed 1240 kg and had gold wheels like the one on the World Rally Championship Impreza.

    The V-limited STi edition was produced. It was a limited edition was often used to celebrate a Manufacturer or Driver title award to Subaru's World Rally Team. The interior is colored blue on the seat inserts and carpeting. The WRX Type RA STi received a radio and air-conditioning in the V-limited form. 1000 WRX STi Version 2 V-limited were produced. 555 (the cigarette brand that was the primier sponsor of the Subaru World Rally Team) WRX Type RA STi Version 2 V-limited were produced.

    Version III (1996) - GC8D: The engine was vastly updated and was given the name Boxer Master 4. It developed the then-established gentlemen's agreement power limit of 280 PS (206 kW). Torque peaked at 4000 rpm with a value of 35.0 kgf·m (343 N·m). The car gained 10 more kilograms and weighed at 1250 kg. The STi shared the same face lift that the rest of the Impreza line received.

    With Version III came the start of the coupe version of the WRX STi. This car was to be the new basis for rally races. It is called the WRX Type R STi. The coupe was chosen by Prodrive because it was smaller, lighter and stiffer than the 4 door version. It was essentially a 2 door version of the WRX Type RA STi meaning it had DCCD, little sound-insulating material, close-gear ratios and the gearbox was hardened. This car also had an intercooler spray to cooler the intake charge for the turbocharger. This car was produced on an order-only basis.

    The WRX Type RA was not produced and there were only 500 of the WRX STi Version 3 V-limited produced.

    Version IV (1997) - GC8E: The power was again increased. This time 280 PS (206 kW) was produced, but the torque was increased to 36.0 kgf·m (353 N·m).

    Again, like the Version II, there were 555 WRX Type RA STi Version 4 V-limited cars produced. The WRX Type R STi Version 4 V-limited was produced on an orders-only basis with a 3 month waiting period.

    Version V (1998) - GC8F: The power stayed the same as the previous version. The engine layout and design was made cleaner. This engine was dubbed as the Boxer Phase2 engine. The facelift the rest of the Impreza line also applied to here. The WRX STi weighed 1270 kg.

    There V in "V-Limited" was dropped. There were 1000 WRX Type RA STi Version 5 Limited cars and the WRX Type R STi Version 5 Limited cars had a 4 month waiting period for each order.

    Version VI (1999) - GC8G: Again the power stayed the same. Most the changes were cosmetic. The wing was sculpted to be more aggressive.

    There were 2000 WRX STi Version 6 Limited and 1000 WRX Type R Version 6 Limited cars produced.

    Japanese-spec Special Variants

    22B STi (1998): In 1998, Subaru of Japan produced a widebody, 2-door, Impreza called the 22B STi. The 22B had the EJ22 engine as opposed to the regular EJ20 engine. This means the displacement was increased from 1994 cc to 2212cc. The block was a closed-deck borrowed from the Legacy's EJ22. The heads (valves, valvetrain and such) were lifted from the STi Version 4 engine. It produce 280 PS (206 kW) and 363 N·m (37.0 kgf·m) of torque at a lower engine speed of 3200 rpm. The redline was lowered from 8000 rpm to 7000 rpm.

    The 22B was used to commemorate the 3rd consecutive manufacturer's title for Subaru in the FIA World Rally Championship. This car was given a unique color of blue and had fender flared widebody taken from the Peter Stevens designed WRC car. It sported a Bilstein suspension, a triple-plate clutch, cryo-treated gears, a unique spoiler, a unique bumper and custom BBS gold wheels.

    The origin of the name 22B has often been debated. Many assume 22 referred to the 2.2 liter displacement and the B was for the Bilstein suspension. This would correlate with the idea that Subaru sells a Legacy Spec B, where the B represents the Bilstein suspension. Others believe that 22B was meant to represent the much recognized 555 decal on the WRC car as 22B is a hexadecimal representation of the decimal number, 555.

    It is interesting to note that the 22B STi that is suppose to be #13 was never given the plaque. Subaru of America imported #13 to be used as a press car.

    S201 STi (2000): Subaru Tecnica International started the S-series of special Imprezas. This series is a limited production series that sports an engine output of greater than 280 PS (206 kW) (special variant cars were excluded from the gentlemen's agreement). The car was decked with nearly every single part from the STi catalogue.

    The S201 was a 4-door STi that sported the only body-kitted S-series WRX STi. It had a tri-planar wing and a massive front airsplitter. The entire suspension was composed of STi parts.

    GD chassis (2001 - present)

    In 2001, the Impreza line received a complete update. The chassis was stiffened so that it had 120% torsional stiffness increase. The WRX STi gained 17" x 7.5" inch alloy wheels over the previous 16" x 7" inch wheels. The 5 speed transmission (reputed to be one of the car's weakpoints) was changed to a STi engineered 6 speed manual transmission. The engine was retained from the Version 6 STi and still retains the semi-closed deck block and is still labeled as the EJ207. The interior was updated with a STi logo on the gauge. The STi's gauge also has a red shift light. The STi's and optioned Type RA STi have received Brembo 4 pot front and 2 pot rear brakes while the bare-bones Type RA STi still carried the Subaru 4 pot front and 2 pot rear brakes. Externally, the STis had larger hoodscoops and had foglight covers with STi embossed on them. The DCCD was updated so it can work with anti-lock brakes. During braking, when the ABS is on, the DCCD will set itself to open-mode (no locking).

    The version nomenclature was dropped from the name. To distinguish between the years, Japanese and other auto-enthusiasts often refer to the chassis as GDB (the STi had a 'B' where as the regular WRX had an 'A') revision A to F where F is the current (2006) version.
    ai13.photobucket.com_albums_a274_CLUTCH_ONE_1stGenSti.jpg ai13.photobucket.com_albums_a274_CLUTCH_ONE_2ndgenSti.jpg

    CLUTCHONE Active Member

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    Rev. A (2001): In 2001, the WRX STi received the aforementioned updates. The WRX Type RA STi was produced. The STi wagon was still produced but it's engine only produced 260 PS (191 kW). The STi foglight covers had white STi lettering on them.

    The WRX Type RA STi was used for the Group N homologation.

    Rev. B (2002): Along with the rest of the Impreza line, the grill and body of the WRX STi was minorly updated by Peter Stevens to give it a more angular look when seen from the side. The foglight covers had pink STi lettering. Not much else besides minor suspension improvements and a small increase in torque output was done.

    The WRX Type RA STi was dropped for a new WRX STi Spec C. This model was much lighter than the WRX Type RA as it received lighter glass and body panels. The Spec C's handing was much improved due to an increase in caster (from 3.5 degrees to 5 degrees). This was achieved not by changing the suspension mounting point, but by lenghtening the wheelbase (15 mm). This was done by including different control arms. This increased caster significantly helped the turn-in capabilities of the car. The Spec C also has a steering rack ratio of 13:1. The transmission is supplied with its own oil cooler.

    The WRX STi was used for Group N homologation.

    The WRX STi wagon had ceased to be produced.

    Rev. C (2003): Not much was changed.

    The WRX STi was used for Group N homologation.

    Rev. D (2004): The WRX STi received the same Peter Stevens-designed facelift that rest of the Imprezas received. The WRX STi is now capable of being ordered with DCCD.

    The WRX STi Spec C Type RA was released. It sported a carbon-fiber wing and a carbon fiber lip. It also had a new set of BBS wheels as well as a newly tuned engine.

    The WRX STi V-limited was released. It sports 4-way dampers tuned by Subaru World Rally Team's Group N driver Toshi Arai.

    The WRX STi was used for Group N homologation.

    Rev. E (2005): The WRX STi receives the same increase in wheelbase as the Spec C. All STis received additional rear fender flaring in order to allow an increase in wheel size. The wheel size went from 17" x 7.5" to 17" x 8". In accordance with the increased wheel width, steering lock-to-lock turns have been reduced. Wheel hub strength was improved. The P.C.D. was changed from 5 x 100 to 5 x 114.3.

    The DCCD mechanism is improved with the addition of a yaw rate sensor that helps the AWD's computer determine torque distribution to the wheels.

    The WRX STi Spec C WR-limited was used for Group N homologation.

    Rev. F (2006): The WRX STi continues on relatively the same. The Impreza line's looks have been changed by Andreas Zapatinas.

    The WRX STi Spec C's receives the Arai tuned dampers and a 21-mm swaybar. The rear suspension is changed from rubber pushings to pillowball bushings. The strut tower was further stiffened for improved handling and stability. The strut towers were reinforced for better handling and better ride characteristics. The engine mounts were changed from metal to liquid-filled plastic mounts to reduce vibrations into the car's cabin.

    The DCCD is updated with the use of a torque-sensing mechanism inside the DCCD. The torque split is changed to 41/59.

    The WRX STi Spec C was used for Group N homologation.

    Japanese-spec Special Variants

    S202: This car was an S-series Impreza based on the Spec C. All of the suspension and powertrain parts included STi parts from the STi part catalogue. The rims were STi labeled Ray's Volks rims.

    S203: This limited edition Subaru was an S-series Impreza based on the WRX STi. Again it is basically a car with all the STi parts available. It was shod with custom made 18 inch BBS rims with Pirellis. The crankshaft is balanced by hand.

    S204: The new S204 was released at the end of 2005. It is based on the WRX STi. It does away with the roof spoiler and has a different grill from the rest of the Impreza line.

    Asia, Oceania and European-spec

    In 2001, most of Asia, Oceania and Europe received the new STi. The engine was detuned to meet emission standards. Instead of the stated 280ps, the engines produced 265 PS (195 kW).

    In 2006, the engine was changed to the EJ25 and produces 280 PS (206 kW). The STis finally received the DCCD that US models had from the beginning and the extra wheelbase increase like the Japanese-spec WRX STi Spec C.

    Subaru Impreza WRX STI 2006 - front (Australian model)

    Subaru Impreza WRX STI 2006 - rear

    Subaru Impreza WRX STI 2006 - engine

    Subaru Impreza WRX STI 2006 - interior driver side

    Subaru Impreza WRX STI 2006 - interior driver seat

    Subaru Impreza WRX STI 2006 - rear badge


    In 2004, Subaru of America announced it will sell the WRX STi. Subaru Tecnica International's president said in an interview that he wishes to best the Mitsubishi Lancer Evolution in the US. Thus, the each iteration of the US-spec WRX STi was essentially the same as the respective J-spec STi Spec C (the highest performing STi version barring special variants). All the part numbers match up, including the part-numbers for the glass windows and dampeners. However, instead of the EJ207, the USA receives the first EJ257, a 2.5 liter version of the EJ207. Also, unlike the EJ207, it features hypereutectic cast pistons as opposed to the forged pistons in the EJ207. The steering rack is the standard STi's 15.2:1 instead of the Spec C's 13:1

    Many people surmise the reason why the US-spec WRX STi does not handle as well as a Spec C is because the EJ257's extra weight and the slower steering rack hampers the feel and balance of the car.

    The current-generation MY2006 STi weighs approximately 3350 lb.

    GC chassis comparison to the GD chassis

    Subaru claims that the GD chassis is 148 percent and 82 percent stiffer in torsional and beam rigidity, respectively, than the GC chassis. Due to the increase in stiffness, the car has much better stability in corners and is easier to control at the limit. The GC chassis is so weak compared to today's cars that engineers called the body a "Watermelon frame", referring to how a watermelon shatters on impact.

    In terms of safety, the IGD chassis scored much higher than the GC chassis and earned a "Good" rating (highest mark) from the IIHS's offset crash test. 4 stars front driver, 5 star front passenger and 4 star side safety ratings from the NHTSA. In a magazine article from the Dec. 2005 Firehouse magazine (a periodical written and made for firefighters), Ron Moore writes how it is well-known that the Impreza chassis has great protection in its B-pillars. This side structure has 8 layers of high-strength, high-tension steel including a round steel bar running through the middle. The author notes how drivers simply walk away from horrific side-impact accidents.


    One of the biggest complaints with the GD chassis is that it gains nearly 200 kg in weight over the GC chassis. Much of this weight came in the form of chassis stiffening as the car was made to meet every countries' crash standards. The weight also hampers the cars manueverability, transistions and turn-in capabilities. The GC Imprezas were notable for being very lightweight despite having 4WD, the WRX Type STi Version VI, at 1260 kg, was lighter than the concurrent Mazda RX-7 type RZ (1270 kg) and Honda NSX type S Zero (1270 kg). In this fashion, the GC chassis has a better advantage.

    The author mentioned above also notes that the Jaws of Life need to cut the Subaru's B-pillars at certain points in order to cut through the car frame. This information was not as well-spread before, so there have been many incidences where firefighters could not cut the B-pillars due to their structural integrity. To some people, this might be a concern if the driver or passengers need to be cut out of the vehicle quickly.

    The STI was originally sold only in Japan. It was later made officially available in Oceania (Australia had it in 1999 with the STi Version V). In 2001, Europe received the STi with the change of the chassis. After seeing the Impreza WRX sell at much better levels than expected, Subaru began selling the STI in North America in 2004.

    It should be noted that the Oceania and Europe actually had WRX STis in the region before the official versions. Car importation laws in those areas are much more lax than America's laws. Thus, the grey markets has many earlier versions of the WRX STi. America's car importation laws are much more strict. In most cases, the only way to legally import an earlier version of the WRX STi than the one offered is by registering it as a race or exhibition car.
  3. JDMFairladyZ

    JDMFairladyZ Administrator

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    Apr 25, 2006
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    Nice post Clutch.:thumbup: Very informative and useful information.:cheers:

    CLUTCHONE Active Member

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    Apr 27, 2006
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    Oh Snap., I Forgot...

    I Forgot to Post Pics of All the Gens... They are comming right Up... :eek:hsnap:

    ~Edit Done~
  5. Specter

    Specter New Member

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    Apr 28, 2006
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    man you must be using dial up... you're late rofl

    but good info
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