Subaru Impreza WRX STI
The Subaru Impreza WRX STI (often referred by auto-enthusiasts as simply STi or also colloquially pronounced as the "Impreza Rex Ess-Tee-Eye"; 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 it 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 verison 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 flares that gave the car a similar width to the 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 inch alloy wheels over the previous 16 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 have received Brembo 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.
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.
Japanese-spec
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): The grill of the WRX STi was minorly updated 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. The Spec C's handing was much improved due to the increase in caster. This was achieved not by changing the suspension mounting point, but by lenghtening the wheelbase (15 mm). This was done by having 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 its own oil cooler.
The WRX STi was used for Group N homologation.
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.
The WRX STi Spec C received numerous updates. One of which is an increase in the strength of the wheel hubs. 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. It receives the Zappatina-designed face lift.
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 mounts were changed from metal to liquid-filled plastic mounts.
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. It was shod with custom made 18 inch BBS rims with Pirellis.
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.
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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
US-spec
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 US-spec WRX STi was essentially the Spec C. All the parts match up, including the part-numbers for the glass windows and dampeners. However, instead of the EJ207, the USA receives the EJ257, a 2.5 liter version the EJ207. However, unlike the EJ207, it features hypereutectic 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
According to some resources, the WRX STi may contain these performance oriented parts: Recaro bucket seats and a MOMO steering wheel. Other performance oriented parts surely on the WRX STi are: Bilstein shocks, Brembo brakes, and BBS 10-spoke alloy wheels available in gold or silver.
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 STi weighs approximately 3350 lb.
GC chassis comparison to the GD chassis
Pros Subaru claims that the GD chassis is 148 percent and 82 percent stiffer in torsional and beam rigidity, respectively, than the GC chassis. It fairs much better in the US IIHS crash testing. Due to the increase in stiffness, the car has much better stability in corners and is easier to control at the limit.
Cons
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).
Motorsports
Rally
PCWRC: The STi (or, more precisely, even further modified versions thereof) serve as the basis from which Group N "production" rally cars are constructed. Group N4-classed (marketed by FIA as Production Car World Rally Championship or PCWRC) cars are the major support category for the World Rally Championship and are the premier category in many national rally championships. For the past two years (2004 and 2005), the WRX STi has taken the top 3 podiums in Group N. This new effort can be attributed to STi's increased support in Group N motorsports.
WRC: In 1995, 1996 and 1997 World Rally Championships, Subaru's World Rally Team, in conjunction with Prodrive won the Group A8 class with the World Rally Impreza. The STi's bare chassis is used by Prodrive as the basis of the World Rally Impreza. This rally class is currently labeled by FIA as Group A8.
Autocrossing
In 2004, the STi Spec C won 1st place in the All Japan gymkhana (Japanese autocrossing) championships. In the US autocrossing competitions, SCCA Solo2, the STi has done very well. At the 2005 Tire Rack SCCA Solo Nations in Topeka, Kansas, a 2004 US-spec STi took 1st in the STU class.
Road racing
In 2005, Prova Racing's STis finished the season in 1st and 3rd place in Japan's Super Taikyu. In 2002, Eifel Prova Racing took 1st place in Super Taikyu. In 2005, Prova Racing took a STI to 2nd place in class and 14th overall in the 24 hour Nurburgring. In SCCA's club racing division T2, Icy Racing's 2004 STis took 1st and 2nd place.
Media
Manga:
The STi is featured in various movies and anime. In Shuichi Shigeno's manga turned anime, Initial D, the main character's father, Bunta, drives a WRX Type R STi Version V with a STi Sports Bumper (a bumper that was sold in the STi parts catalogue; it had the same shape as the 22B STi but was made to fit the non-wide body Imprezas).
Anime:
In the anime, Ex-Driver, a '99 Impreza WRC was shown in the first episode. Unfortunately, it was totaled in the episode (the power line for the car's 6-speed sequential transmission was damaged by a runaway AI car, making gear changes impossible).
Movies:
In the Hong Kong movie, "Legend of Speed 2", two street racing teams compete in the streets of Kowloon, Hong Kong. One of the teams races WRX STis. The leader drives a white WRX STi version 3.
Games:
This car is also featured in the Gran Turismo game series for the PS2.
TV:
A 2004-2005 STi is also featured in a Taco Bell commercial. In the Quaker State oil ad, they feature a stock WRX STi on the commercial and on magazines.
Availability
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 VI). 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.