Subaru Impreza WRX STI

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Subaru Impreza WRX STI
2004-2005 Subaru Impreza WRX STi
Manufacturer Subaru
Parent company Fuji Heavy Industries
Production 1992–present
Assembly Ōta, Gunma, Japan
Class Sport compact
World Rally Car
Layout Front engine, symmetrical all wheel drive

The Subaru Impreza WRX STI (formerly WRX STi, officially changed in 2006) [1] is the highest standard-edition trim in the Subaru Impreza compact car line, produced by Japanese automaker Subaru.

In the late 1980s, Subaru created the Subaru Tecnica International (STI) division to coordinate development for the FIA World Rally Championship and other motorsports activities. After the company had grown, the division was used to create high-performance consumer versions of the Subaru Impreza WRX, an all-wheel drive car with a turbocharged flat-4 engine, leading to the development of the Impreza WRX STi. The Subaru World Rally Team has used a race-prepared version of the WRX STI as its rally platform since the model trim's creation.


[edit] Motorsports

[edit] Rally

2006 Subaru Impreza S12 WRC, a car based on the design of the '06 spec (Rev. F).

[edit] FIA PWRC

The STi 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 PWRC) 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.

[edit] FIA WRC

In 1995, 1996 and 1997 World Rally Championships, the Subaru World Rally Team, in conjunction with Prodrive won the WRC manufacturer's title with the World Rally Impreza. The STi's bare chassis is used by Prodrive as the basis of the World Rally Impreza. This WRC class is currently labeled by FIA as Group A8. Colin McRae in 1995, Richard Burns in 2001, and Petter Solberg in 2003 all won the WRC driver's title with the World Rally Impreza.

[edit] Rally America

2006: Travis Pastrana drove a 2006MY STi to capture the national title overall, as well as in the Open Class. Several other teams entered driving STIs.

2007: Travis Pastrana drove a 2007MY STi to capture the national title overall, as well as in the Open Class.

[edit] Autocrossing

[edit] JAF Events

2004: The STi Spec C won 1st place in the All Japan gymkhana (Japanese autocrossing) championships.

[edit] SCCA Events

As of 2006, all GD-chassis STIs can compete in A Stock (AS), Street Touring Ultra (STU), B Street Prepared (BSP) and Street Modified (SM).

2005: At the Tire Rack SCCA Solo Nationals a 2004 US-spec STI took 1st in the STU class.

2006: At the Tire Rack SCCA ProSolo in Topeka, Kansas US-spec STIs took first place in AS and STU. At the Tire Rack Solo Nationals a 2004 US-spec STI took first place in STU.

[edit] Road racing

[edit] FIA Events

2005: Chris Deeble took a STI-supported WRX STI to 2nd place in the A6 class and 14th overall in the 24-hour Nürburgring race. The car was set up to have around -5 degrees of camber at the front wheels. The wheels are Enkei pieces. The car also uses the roof vane seen on the 2006MY WRX STI. The car used Tein SRC coilovers. The car was driven by Kazuo Shimizu (Super Taikyu driver and winner), Toshihiro Yoshida (Super Taikyu driver and winner), Stéphane Sarrazin (2005 Subaru World Rally Team driver) and Kumi Sato.[2]

2006: Deeble-Bellchambers {DB-RT} Racing UK campaigned a Subaru factory supported WRX STI Spec C in the 24 Hour Nürburgring's SP 6 class. It had Motec Engine Management, 3-way adjustable AST coilovers, aftermarket Brembo brakes, an aftermarket turbocharger unit, STI Group N parts, aero pieces and many other modifications. It was pushing 400 hp (300 kW). To combat understeer, it ran without a front swaybar. It qualified 37th out of 225 competitors for the starting position. The Autosportif Racing UK/Subaru WRX STI Spec C managed to end with a position of 115 out of the 225. It had suffered 2 turbocharger unit failures during the course of the race. The car was driven by Alan van de Merwe (the 2003 British F3 champion), Briton Phil Bennett (driven in the BTCC, Le Mans and Nürburgring), Jonathan Price (6-time Nürburg 24 Hours competitor) and Chris deeble (2006, 2007 Subaru World Rally Team driver).[3]

[edit] SCCA Events

2005: In Club Racing's T2 division, Icy Racing's 2004MY STis took 1st and 2nd place. ESX Motorsports announced the introduction of the WRX STI in World Challenge's GT class.

2006: Icy Racing's 2006MY STIs took 1st and 2nd place.

[edit] Super GT

The Cusco team have been campaigning a heavily modified STi with rear drive conversion as required by regulations since the late nineties and having no two-door model available at present, the Super GT committee gave a special permit for them to race with a four-door model instead of two-door one. The rear drive conversion rule was lifted in 2006, and since then they return to AWD with a transaxle gearbox.

In 2008, Cusco's Impreza won the first GT300 race in Sepang, marked the first AWD car victory in Super GT/JGTC history. Even they were having very impressive result (with 1 win and 2 podiums) that season, the Cusco announced they are not participate in the 2009 season as they want to concentrate on off-road events.

As the performance of the Cusco was outstanding even they were using a 4-door car, it later leads the Super GT committee to officially allow all 4-door model cars to participate the series, and the Toyota Corolla Axio followed suit in 2009.

[edit] Subaru Impreza WRX STI Super GT Specifications (2008)

  • Chassis: Tubular frames with bellhousing, integrated driver safety cell and defined front must be FIA, JAF approval.
  • Engine: Custom-built Subaru EJ-20 engine, Horizontally Opposed 4-cylinder Single turbo charger, 1994 cc, DOHC, 2-valves per cylinder.
  • Bodywork: Cusco.
  • Power: Over 300ps.
  • Torque: Over 40kgf/m.
  • Roll cage: SAFETY21.
  • Gearbox: 6-speed sequentially transaxel AWD gear-box.
  • Differential: Mechanical L.S.D., Front:CUSCOType-RS. Center: 1WAY RS . Rear: 1WAY RS.
  • Brakes: Endless.
  • Clutch: EXEDY carbon 5.5in
  • Wheelbase: 2540 mm.
  • Length: 4465 mm.
  • Height: 56.3 ".
  • Width: 1840 mm.
  • Weight : 1150 kg.
  • Fuel Capacity: .
  • Springs: Cusco.
  • Suspension arm: CUSCO pillow ball suspension.
  • Damper: ZF Sachs.
  • Wheels: Front/Rear: Racing Hart CP-035 MAG 11.0J-18.
  • Tires: Dunlop Direzza 280/710 R18 (F&R).
  • Fuel: Moty's.
  • Oil: Moty's.
  • Fuel delivery: Injected fuel system.
  • Racing seat: BRIDE GARDIS􁶙􀊢CFPR􀊣.
  • Seatbelt: TAKATA MPH-350R.
  • Team: Cusco Dunlop Subaru Impreza.

[edit] Drifting

[edit] D1 Grand Prix

2005: Nobushige Kumakubo is the first to use an GD-chassis WRX STi at the D1 Grand Prix series. The car is extensively modified as regulations permit only two wheel drive cars. This STi is unique in that it is the first to locate a radiator (with the fan beside it) behind the driver rather than in front of the engine compartment as other cars usually do. His other Team Orange teammates, Kazuhiro Tanaka and Naoto Suenaga, soon followed suit.

2006: Team Orange and Jun Autosports have converted a GC-chassis 2-door STi into a RWD vehicle for drifting to be used by third driver Naoto Suenaga. Drivers Nobushige Kumakubo and Kazuhiro Tanaka took a single win each during the 2006 season and the former took the overall D1GP title.

[edit] 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 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,[citation needed] Subaru began selling the STI in North America in the spring-summer of 2003 as a 2004 model.

Oceania and Europe had WRX STis in the region before the official versions via grey-market importing.[citation needed]

Five (5) WRX STI S204 were made available to Subaru enthusiasts in New Zealand. However, unlike other S204s sent to other nations these five did not display either the in-cabin or in-enginebay badging that uniquely identifies each of the reported 600 vehicles manufactured.[citation needed] The lack of individual badging for these five cars brings into question the real number of S204s manufactured.[citation needed]

Thirty (30) WRX STI S204s' were made available to Singapore through the main distributor - Motor Image Enterprises.

[edit] GC chassis (1992 - 2001)

1995 Subaru Impreza WRX STi RA.
Production 1992-2001
Body style(s) 2-door coupé
4-door sedan
5-door station wagon
Engine(s) 2.0 L H4
Wheelbase 99.2 in (2520 mm)
Related Subaru Impreza
Subaru Impreza WRX
Subaru Forester

There were six 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. Sedan STi Model Codes were GC8, Coupes were GM8 and Station Wagons were GF8, followed by a letter from A to G. There was a GC chassis version of the RS released in 2001 as well in the United States.

One common misconception is that every Impreza between 92-01 were "GC8's". The code breakdown is as follows; G - stands for Impreza, C - sedan, M - coupe, F - station wagon, The 8 stands for the 2.0 L turbo motor. So really, there are many combinations. A coupe STi would be GM8, sedan GC8, wagon GF8. Also, the code for the coupe American 2.5RS's were GM6 (6 standing for the 2.5 L N/A motor)

A JDM Sti Coupe has the code GC8. For example a version 4 Sti coupe has the code GC82DD. With the 2 representing 2-doors.

[edit] Japanese-spec

[edit] Version I (10/92 – 08/94) - GC8A/B

The first STi was known simply as "STi" (there was no "version" moniker added to the name until the version II). 100 Imprezas per month were produced starting from February 1994. In March, production was stabilized to 100 STis a month. It had 250 PS (184 kW; 247 bhp) at 6500 rpm and 31.5 kgf·m (309 N·m) at 3500 rpm and weighed 1230 kg (2,710 lb). Before the STi, the highest trimline of the Impreza was the WRX and the WRX RA, first manufactured in November 1992. This version of the STi 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 STi Type RA (marketing has made usage of the RA acronym in various ways; Record Attempt[4] is the current usage. "R = Racing, A = Group A, FIA the racing class the WRC Impreza competes in" has also been confirmed by Subaru of Japan; the correspondence can be seen on the discussion board for this article) produced 275 PS (202 kW; 271 bhp) 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. The DCCD would be beneficial to people who used it in various rally conditions.

[edit] Version II (09/95 – 08/96) - GC8C

The regular STi's engine output stood at 275 PS (202 kW; 271 bhp) and 32.5 kgf·m (319 N·m) of torque. This was the year that STi started painting the intake manifold red. The car weighed 1240 kg (2734 lb) 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 that 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 premier sponsor of the Subaru World Rally Team and became synonymous with the Impreza WRC livery) WRX Type RA STi Version 2 V-limited were produced. And that's that.

[edit] Version III (09/96 – 08/97) - GC8D

The engine was vastly updated and was given the name Boxer Master 4. It developed about 300PS but output was reported at the then-established gentlemen's agreement power limit of 280 PS (276 hp/206 kW). Torque peaked at 4000 rpm with a value of 35.0 kgf·m (343 N·m). Standard this version has a top speed of over 240 km. The car gained 10 more kilograms and weighed at 1250 kg (2756 lb). 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. It is called the WRX Type R STi. The coupe was chosen by Prodrive for use in the WRC 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, minimal sound insulation, close-gear ratios and hardened gearbox. This car also has a water-spray nozzle to dampen the top of the intercooler. The water will then evaporate, taking heat away from the intercooler and cooling the intake charge. This car was produced on an order-only basis.

Also there was WRX STI type RA (4-door) available in Version 3, they have the same motor, gearbox and R180 diff as the Version 3 WRX STI Type R, including DCCD, aluminium bonnet and front guards, no sound deadening and thinner glass. The ECU is also an exclusive tune. The Type R tends to be a bit stiffer and weighs 1190 kg (2624 lb). The DCCD has been known to bite new drivers in the wet. The RA gets a roof vent, instead of map lights, and wind up windows, although electrics are an option from factory.

Also available was a WRX Type R V-limited, in version 3. It has a WRX motor with no forged internals like the STI, and it misses out on the 4 pot front brakes as they are to be installed by rally teams. It has a roof vent and is lightweight, making a good base for a rally car.

Version 3 STI runs a VF23 IHI ball bearing turbocharger while the JDM non-STI gets a VF22.

[edit] Version IV (09/97 – 08/98) - GC8E

Power remained at 280bhp

The interior and the cockpit were changed into a newer design along with the new "white color" guages.

[edit] Version V (09/98-08/99) - GC8F

The power stayed the same as the previous version. The engine layout and design was made cleaner and was dubbed as the Boxer Phase 2 engine. The facelift the rest of the Impreza line had was also applied to the STi. The WRX STi weighed 1270 kg (2800 lb). 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. The interior was also changed slightly from the Version 4 including seats and steering.This model was also produced as a 555 limited edition.

[edit] Version VI (09/99-08/00) - GC8G

Production 1999-2000
Body style(s) 2-door coupé
4-door sedan
5-door station wagon
Engine(s) 2.0 L H4
Wheelbase 99.2 in (2520 mm)
Related Subaru Impreza
Subaru Impreza WRX
Subaru Forester

Again the power stayed the same. Most of the changes were cosmetic. The wing was sculpted to be more aggressive.

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

[edit] Japanese-spec Special Variants

[edit] 22B STi (03/98 – 08/98)

In 1998, Subaru of Japan produced a widebody, 2-door, Impreza called the "22B STi". The 22B was used to commemorate both Subaru's 40th anniversary as well as the 3rd consecutive manufacturer's title for Subaru in the FIA World Rally Championship. On the release of the sales, all 399 sold out from 30 minutes to 48 hours, depending on the report.[5] The cars had the starting VIN code of GC8E2SD. Another 25 were produced for export markets - see the 22B Type UK below.

The 22B had the EJ22 engine as opposed to the regular EJ20 engine. This means the displacement was increased from 1994 cc to 2212 cc. The block is a closed-deck design. The heads (valves, valvetrain and such) were lifted from the STi Version 4 engine. It produce 350 PS (345 hp/257 kW) at 6000 rpm and 363 N·m (267 ft·lbf/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 compression is an 8.0:1. The turbocharger is an IHI RHF 5HB (the internal company usage code is VF23).

This car was given a unique color of blue and had fender flared widebody taken from the Peter Stevens designed WRC car, thus widening the width by 80 mm (3.15 inches) for a total of 1,770 mm (69.7). During assembly, a WRX Type R chassis was taken off the line. The fenders were replaced with the 22B STi fenders. The car's curb weight is 1,270 kg (2,800 lb). The suspension is provided by Bilstein. The brakes were standard 4-piston/2-piston brakes. However, the color is red and the Subaru name casted on the brake calipers and painted white. The wheels were increased in size from the standard WRX Type R STi from 16x7" to 17x8.5" BBS Elektra wheels. The car is shod with 235/40 ZR17 Pirelli P Zeros. The clutch was upgraded to a sintered twin clutch with a ceramic disk. The transmission ratios are the same as the standard WRX Type R, but the gears were shot-peened for added reliability. The car has a unique hood, a WRC-inspired front bumper and a unique adjustable rear wing.

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 (555 is a tobacco company that was a major sponsor for Subaru in the WRC) on the WRC car as 22B is a hexadecimal representation of the decimal number, 555.

It must be noted that the 22B STi that is supposed to be #13 was never given the plaque. Subaru of America imported #13 to be used as a press car. Three 22B STis were given the #000 plaque, 2 went to the World Rally car drivers for Subaru at the time Colin McRae and Nicky Grist, with the third going to David Lapworth of Prodrive.[6]

[edit] 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 (276 hp/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.

[edit] UK-spec Special Variants

[edit] 22B Type UK (1998)

16 of the 'export' 22Bs (see above) were modified by Prodrive, with longer gear ratios, UK lights and driving lights and an official 3 year warranty. Because 50 22Bs had already been imported privately into the UK, Subaru UK had to wait until 1999 to register the 22B Type UKs under the Single Vehicle Approval scheme. The price was £39,950, which was roughly what grey import 22Bs were going for.

[edit] P1 (2000)

To counter the grey imports of high-performance Japanese variants, Subaru UK commissioned Prodrive to produce an 'official' limited edition of 1000 two-door cars in Sonic Blue.[7] The chassis was a 2-door coupe. They were taken from the STI Type R lines and used for the P1. The car was the only coupe version of the WRX STI GC chassis to receive ABS. In order to allow for ABS, the DCCD was dropped. Engine output was boosted to 276 bhp (206 kW), and the suspension optimised for British roads. Options were available from Subaru consisting of 6 piston front brake calipers, electric Recaro seats, 18" OZ alloys and a P1(Prodrive) stamped backbox. The P1, or Prodrive One, is echoed in the name of the Prodrive P2 concept car.

[edit] GDB chassis (2000 - 2008)

2005-2008 US-spec Subaru Impreza WRX STI
Production 2000-2008
Body style(s) 4-door sedan
4-door station wagon
Engine(s) 2.0L H4
2.5L H4
Transmission(s) 6-speed manual
5-speed semi-automatic
Wheelbase 2004-05: 100.0 in (2540 mm)
2006-08: 99.4 in (2525 mm)
Length 2004-05: 173.8 in (4415 mm)
2006-08: 175.8 in (4465 mm)
Width 68.5 in (1740 mm)
Height 56.3 in (1430 mm)
Curb weight 3,296 lb (1,495 kg)
Related Subaru Impreza
Subaru Forester
Subaru Impreza WRX
Saab 9-2X

In 2000, 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" alloy wheels over the previous 16" x 7" wheels. The 5 speed semi-automatic transmission (reputed to be one of the car's weakpoints) was changed to an 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, However, the turbochargers are IHI models. The interior was updated with a STi logo on the gauge. The STi's tachometer also has a red shift light. The STi's and optioned Type RA STi have received Brembo 4 piston front and 2 piston rear brakes while the bare-bones Type RA STi still carried the Subaru 4 piston front and 2 piston 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. Japanese and other auto-enthusiasts often refer to the chassis as GDB/GDF (the STi has a 'B' or 'F'(for USDM models) where as the regular WRX had an 'A'). The forth charter of the VIN gives the revision (A to F where G is the current (2007) version).

[edit] Japanese-spec

[edit] Rev. A (2000)

In 2000, the WRX STi received the aforementioned updates. The WRX Type RA STi was produced. The STi wagon was still produced but its engine only produced 260 PS (191 kW; 256 bhp) . The STi foglight covers had white STi lettering on them.

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

[edit] Rev. B (2001)

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 handling 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 lengthening 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 wagon had ceased to be produced.

[edit] Rev. C (2002)

Little change from Rev. B.

The WRX STi was used for Group N homologation.

[edit] Rev. D (2003)

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.

[edit] Rev. E (2004)

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 mm to 5 x 114.3 mm. The interior was vastly improved as well. A whole new center console now brings out a very high grade interior feel.

This was the first Impreza STi model to be offered in the United States. Subaru unveiled this model in the Detroit International Auto Show, only 1 month after Mitsubishi announced the arrival of the 271 horsepower Lancer Evolution 8, which out-performed the 2.0L WRX.

The 2004 WRX STi is considered to be the lightest (3263lbs, official brochure and tested by Car & Driver Magazine) and rawest among 2004-2009 models. The car was sold without a radio or floormats. The car was rated at 300 bhp and 300 lbs-ft torque, although many feel it was under-rated on purpose. What made the car so special to most is the level of performance offered for a mid 30 thousand dollars car, that still has a back seat and a big trunk.

Since its launch, many upgrades became available to increase power, handling and braking capabilities. Most noticeable power upgrade is the Cobb Tuning ( stage 1 and stage 2 power packages. Stage 1 consists of an ECU (computer software) reflash boosting horsepower to 325 bhp and torque to 340 lbs-ft. This upgrade takes 10 minutes to complete.

Stage 2 ups the power to 350 horsepower and 385 lbs-ft torque with the addition of a downpipe and exhaust. Many owners and tuners also recommand replacing the factory fuel pump (at that point) with a walbro 255 unit in order to enable good fuel supply to the engine. The next step is usually a dyno tuning session by any Cobb ProTuner authorized tuning shop, tuning enables to customize the computer software to each particular car addressing areas such as boost levels, fuel delivery, ignition and timing. It is also an advantage with any other modifications done to the engine.

Other upgrade paths include larger turbochargers, headers, built blocks. It isn't uncommon to find certain cars making between 450-800 horsepower, all from a fully built Boxer turbo engine, which is still 4 cylinders.

Some weak links were discovered in most 2004-2007 models since the 2004 debut. The IHI VF39 turbocharger wastegate may develop cracks that may or may not affect performance.

The oil pickup line inside the oil pan was shown to develop a crack leading to oil starvation and engine damage due to the lack of lubrication when the part fails. Several aftermarket vendors have addressed this issue by re-designing factory oil pickup units with beefier welds/materials.

[edit] Rev. F (2005)

The WRX STI continues on relatively the same. The Impreza line's looks have been updated.

The WRX STI Spec C's receives the Arai tuned dampers and a 21 mm (0.8 in) swaybar. The rear suspension is changed from rubber bushings 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. Some 2006 owners have had issues with these plastic engine mounts. The manufacturer will replace them, under warranty if broken, with the 2005 rubber mounts.[8]

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.

The WRX STI Spec C Type RA was released in November 2005, with 350 units produced. The Type RA added the following to the Spec C model from the STI parts catalogue: 4-way STI adjustable inverted struts, STI Japan-spec pink springs, STI rear lateral links, STI rear trailing links, STI 21 mm (0.8 in) rear sway bar, STI rear pillowball suspension, STI 110 mm (4.3 in) opening rear axleback exhaust, STI 17" x 8" Enkei-made wheels and STI V-lip front spoiler.

[edit] Rev. G (2007)

The WRX STI and STI Spec C is mechanically similar to the previous revision.

Changes include a slightly larger turbo (VF43, as opposed to VF39 in the older version) and revised gearing on the 6 speed manual transmission. They also use top feed injectors instead of side feed injectors like the previous STi models(04-06USDM). This means the intake manifold is a bit different as well as the TVG(Tumble Valve Generators) used for emissions on cold start-ups.

[edit] Japanese-spec Special Variants

[edit] 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 interior included special edition black seats with red STi logo stitching. A smaller, lightweight AC compressor was fitted to save weight. The brake rotors were gas slotted. The wheels were STi labeled Ray's Volks alloys.

[edit] 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 sold with custom made 18-inch (460 mm) BBS alloys with Pirellis.

[edit] S204

The new S204 was released at the end of 2005. It is based on the WRX STi and similar to the S203. It does away with the roof spoiler and has a different grille from the rest of the Impreza line. The S204 has a two-litre (EJ20) H4 engine capable of developing 235 kW (320 PS; 315 bhp) and a six-speed manual gearbox. When cruising the S204 achieves 100 km/h (62 mph) at 3000 rpm in top gear and can reach 220 km/h (137 mph) at 6000 rpm.

Suspension can be described as 'stiff' with torsional rigidity enhanced by the inclusion of laterally mounted items described as "performance dampers" bearing both the STi logo and Yamaha. As a result cornering can be described as excellent.

Recaro has used carbon-fibre extensively in the manufacture of the driver and front passenger seats available in the S204. The high side bolsters provide significant support to the driver during maneuvers that induce lateral forces and are considered to be an integral feature to the cornering performance of this vehicle. The seats are rigid in design and have relatively little cushioning compared to other Impreza Models.

The addition of a carbon fibre front-lip spoiler and a rear diffuser on an already low suspension setup plus the use of low-profile Pirelli P Zero (Corsa) tyres implies the S204 is intended mostly for sealed road use.

[edit] WRX STI Spec C Type RA-R

At the end of October, 300 2007MY WRX STI Spec C Type RA-Rs were open for ordering. These cars are based on the WRX STI Spec C. The wheels are changed for 18-inch (460 mm), STI-branded, Enkei-made, white wheels. The engine has been blueprinted and balanced. It produces 320 PS (316 hp/235 kW) of power. The suspension is built with the latest STI parts from the STI catalogue. The front brakes are 6-piston brembo brakes. The brakes are made so that they change from silver to gold when heated from usage. The rotors are slotted. The 2nd R in "RA-R" is stated by an STI engineer to mean "Radical".February 2007 Edition Best Motoring Interview of STI engineer at 7:00

color code: gun metal

[edit] WRX STI A-Line

This WRX STI A-Line is mechanically the same as the Japan-spec STI. The exterior has been toned down with the removal of large rear spoiler, black Brembo brakes, titanium colored Enkei wheels, a black STI front lip and leather seats in order to target the more mature market.

[edit] 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. Engine output was variously rated from 265 PS (261 hp/195 kW) to 280 PS (276 hp/206 kW) depending on market.

2005 STis received the long awaited DCCD control available in other markets, as well as a slight wheelbase increase to match the Japanese-spec WRX STi Spec-C.

In 2006, the model was facelifted like all STIs and the engine was changed to the EJ257 producing 280 PS (276 hp/206 kW).

[edit] UK Special Variants

THE UK version of the WRX STI, taken at the Canary Wharf motor expo in June 2007.

[edit] WR1 (2004)

A limited edition of 1000 Japanese MY04 WRX STI's with DCCD were exported to celebrate victory in the 2003 WRC driver's championship. 500 were sold in Europe, Australia and South Africa as the Petter Solberg edition, the other 500 were further modified by Prodrive and sold in the UK as the WR1. They had 316 bhp (236 kW) and 309.8 ft·lbf (420.0 N·m), an incredible 0-60mph time of only 4.25seconds and a top speed of 155 mph (249 km/h) limited, Prodrive WRX STI springs, Pirelli PZero Nero tires, mesh grilles, Ice Blue metallic paint and Prodrive PFF7 Pewter wheels. The new ECU and exhaust were not EU homologated, so had to be fitted after registration of the car. Price was £29,995.

[edit] Spec D (2006)

A 'discreet' version of the STI was made for a more conservative market. It is similar to the Japanese-spec A-Line except it had regular WRX spoiler on the boot, silver wheels (not Gold) and removal of the rear roof vane,it has projector fog lights Smartnav with touch screen operation (1 years free subscription), Tracker (1 years free subscription),and safe speed as standard although this was only free for the first month (subscription after that). A Pioneer DEH-P70BT sound system with an output of 200 W and a plug in iPod adapter is also standard., with Bluetooth phone connection. along with leather trim to seats and doors Auto climate control was also standard. It was limited to a run of 300 cars in one colour only, that was Crystal Grey Metallic so therefore is rarer than the RB320 that had a run of 320 cars. Power on this model is rated at 277 bhp (207 kW). It has a 0-60 time of 5 seconds and a top speed of 158 M.P.H. It sold for £28,450.

[edit] RB320 (2007)

Subaru Impreza RB320

Echoing the RB5, a limited edition of 320 2007MY cars in Obsidian Black Pearl were released "in memory of Richard Burns", the 2001 WRC World Champion who had died in 2005 due to a brain tumor. The car produces 320 PS (316 hp/235 kW) of horsepower and 450 N·m (332 lb·ft) of torque due to tuning by Prodrive. The suspension has been upgraded with Eibach springs, an Eibach rear stabilizer bar and Bilstein struts. It rides on 18" anthracite alloys. A £1500 option on the car was to have the interior changed to a black leather/alcantara with RB320 stitching on the seat and a new shift knob. The car has silver mesh grilles. The price is £29,995 on the road.[9]

[edit] UK Unofficial Variants

[edit] Litchfield Type 25 (2004)

Litchfield Imports[10] initially imported Japanese Spec C cars into the UK. When Subaru removed creature comforts like air conditioning and electric windows from the Spec C at the end of 2003, Iain Litchfield wanted to continue to offer an 'everyday' car as fast as the Spec C. So he imported EJ257 engines from the US, tuned them to produce 350 bhp (261 kW), and then installed them into a Japanese STI. The suspension was upgraded with AST Sportline I adjustable coilovers, Whiteline stabilizer bars and an anti-lift kit. The May 2004 edition of EVO magazine][11] called it the 'Best Impreza Ever' when tested against the WR1, Spec C and P1.

[edit] Litchfield Type 25 (2007)

The new Type 25 is based on the 2007 Spec C, but the engine block and heads has been developed by Cosworth US to give 415 bhp (309 kW) and 420 lb·ft (569 N·m), for a power/weight ratio greater than a Porsche 997 Turbo. The car can be ordered with optional Porsche brake system.

[edit] US-spec

[edit] Rev. D (2004)

In 2004, Subaru of America announced it will sell the WRX STi. Subaru Tecnica International's president said in an interview with Road & Track magazine that he wishes to beat the Mitsubishi Lancer Evolution in the US. Thus, each iteration of the US-spec WRX STi was essentially the same as the respective J-spec STi Spec C. 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. 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

[edit] Rev. E (2005)

As with the Japanese-spec C models, US-spec 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 Suretrac L.S.D. in the 04 model was replaced with the Helical limited slip differential. In the interior, the Stereo became standard. The badging has been revised and different look was given to the steering wheel, shift knob, HVAC controls, and center console.

[edit] Rev. F (2006)

The US-spec STIs receive the same facelift as the Japanese-spec STIs. Mechanically speaking, the DCCD and the engine mounts have been changed. Like the Japanese-spec STIs engine mounts were changed from metal to liquid-filled plastic mounts to reduce vibrations into the car's cabin. On the largest Impreza forum, North American Subaru Impreza Owners Club, 2006MY owners have had issues with these plastic engine mounts. The manufacturer will replace them, under warranty, if broken, with the 2005MY rubber and metal mounts. Later 2006MY vehicles were equipped from the factory with 2005MY mounts. The center differential is updated with the addition of a mechanical limited slip mechanism to supplement the electromagnetic DCCD. The torque split is changed to 41/59. The 2006MY STI weighs approximately 3,350 lb (1,520 kg).

[edit] Rev. G (2007)

2007 US-spec Subaru Impreza WRX STi Limited. Only 800 were produced.

In 2007, quite a number of changes were made to the US-spec model. Due to Subaru's decision to reduce costs by cutting the amount of aluminum used, the US-spec STI no longer receives the J-spec Spec C control arms. The control arms are now the aluminum ones used on the Japan-spec revision A and B non-Spec C STis. The high caster angle has been reduced, which in turn reduces the wheelbase from 100" to 99.4". The rear sway bar has decreased in size from 20 mm (0.8 in) to 19 mm (0.7 in). The gear ratios of second, third and fourth gears have been made longer (higher ratio) in order to improve fuel economy and driveability, which inadvertently reduces 1/4 mile drag racing times due to the ability to trap 114 mph (183 km/h) in 4th gear, without the shift to 5th. The EJ257's cylinder heads have been redesigned to improve cooling, and the sodium-filled exhaust valves have been deleted. Pistons are the same as previous years also came with the new valves and cylinder heads. The alternator is changed from a 90A rating to 110 amps. The rear Limited Slip Differential is now a Torsen unit, considered an upgrade over the previous model's helical unit. The turbo has also been changed to the VF43, which has a different wastegate actuator than the VF39. The side cowl braces are stiffer than the 2006MY. The engine mounts are once again the hard rubber mounts used prior to 2006. On the interior, there is an audio jack that replaces the ashtray, a rear center armrest with trunk pass-through and a 120 W audio system.[5]

The ECU was completely re-engineered in order to meet US LEV2 emissions requirements, which has caused throttle and timing issues. A secondary air pump was also added to help meet LEV2. Top Feed injectors replaced the Side Feed from the previous models.

The WRX STI Limited is introduced. It is similar to the Japan-spec STI A-line, except the mechanicals of the car are based on the 2007MY US-spec WRX STI.

[edit] GC chassis comparison to the GD chassis

[edit] Pros

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.

In terms of safety, the GD 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 December 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.

[edit] Cons

One of the biggest complaints with the GD chassis is that it gains nearly 200 kg (441 lb) 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 country's crash standards. The weight also hampers the cars maneuverability, transitions and turn-in capabilities. The GC Imprezas were notable for being very lightweight despite having AWD, the WRX Type STi Version VI, at 1260 kg (2778 lb), 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.[12]

[edit] GE/GH/GR chassis (2007-Present)

2008 Subaru Impreza WRX STI (US)
Production 2007-Present
Body style(s) 5-door hatchback
Engine(s) 2.0L 304 hp (227 kW) H4
2.5L 305 hp (227 kW) H4
Transmission(s) 6-speed manual
Wheelbase 103.3 in (2624 mm)
Length 173.8 in (4415 mm)
Width 70.7 in (1796 mm)
Height 58.1 in (1476 mm)
Curb weight 3,373 lb (1,530 kg)
Related Subaru Forester
Subaru Impreza
Subaru Impreza WRX
Subaru Impreza WRX STi 2008

The 2008 STI has received a higher degree of parts to differentiate it from its Impreza WRX brethren. Unlike the Impreza WRX, the STI uses aluminum suspension components, is only available as a 5-door wagon, and has different fenders that are 8" wider. The turbo forces air through a larger top-mount-intercooler which has lost the red "STI" that was on previous generations.

Like other 2008 Impreza models, the 2008 car benefits from a lower polar moment of inertia due to smaller overhangs, and also features a double wishbone rear suspension.[13] The car also borrows new intake and exhaust components from the Legacy GT platform.

The J-spec version has a 2.0L 304 bhp (227 kW; 308 PS) EJ207 engine with a twin scroll turbocharger, while other versions of the car have a 2.5L 305 bhp (227 kW; 309 PS) EJ257 engine with a single-scroll VF48 turbocharger.

Currently, a Subaru WRX STI spec.C is in the works for production. It has been spotted lapping the Nurburgring. It is expected to shed 70 kg in weight, have minor engine tweaks, have an updated aero kit, and bigger brakes.

A possible precursor to the WRX STI spec.C had surfaced at the MotorSport Japan 2008 auto show, named the Subaru Takumi concept. The only visual cues to differentiate this car from the regular STI are a blacked-out rear spoiler, front lip spoiler, and 12-spoke wheels that are strikingly similar to the ones featured on the spec.C test mule spotted around the Nurburgring. The upgraded parts included on the car are drivetrain and suspension modifications. There is no word on performance figures or power output. It was later confirmed by Autoblog that the Takumi concept was in fact just an unveiling of the 20th Anniversary Edition of the WRX STI and not the spec.C. [14] All 300 examples will be exclusive to the Japanese market.[14]

The latest US model of the STI has 305 bhp (227 kW; 309 PS) and 290 ft·lbf (390 N·m). of torque and range in price from $35,640 to $39,440, depending on the options included. The 2008 US Impreza STI has the model code GR, reflecting the different 'wide body 5-door' chassis as compared to the GH '5-door' chassis used for the US 2008 Impreza WRX. The new 'wide body 5-door' chassis is 70.7 in (1796 mm) wide compared to 68.5 in (1740 mm) for the regular WRX '5-door' chassis. Curb weight varies from 3,373 lb (1,530 kg) to 3,395 lb (1,540 kg) depending on the options.

At the New York Autoshow, a Subaru spokesman confirmed that the Impreza WRC will be based on the hatch platform, due to its lower polar moment of inertia.[13]

Subaru (UK) Limited will introduce two new WRX STI models at the British Auto Show that have specific tuning by Prodrive. The first of the two will be the WRX STI 330S, intended to compete with the UK-spec Lancer Evolution X FQ-330. It produces 330 PS (243 kW; 325 bhp) and has a 0-60 mph time of 4.4 seconds. The last of the two will be the WRX STI 380S. It could make it into production within 6 months, pending positive consumer reception. It sports new wheels and an upgraded body kit. It is expected to produce 380 PS (279 kW; 375 bhp). Currently, there are no other specs for the car.

Subaru announced, on September 10, 2008, that the 380S variation will not be produced, due to homologation and specification difficulties. There are plans to replace this variant with a Limited Edition Model, during 2009.

The Singaporean, Australian and Malaysian (all RHD countries) markets will receive the 2.5 liter Euro-spec version instead of the J-spec version, producing 296 horsepower (221 kW) and 407Nm of torque.[15]

Japanese Version Non-Japanese
Turbo twin-scroll turbo single-scroll turbo
Displacement 1997 cc 2457 cc
Power 308 PS (304 hp/227 kW) 309 PS (305 hp/227 kW)
RPM 6,400 6,000 rpm
Torque 422 N·m (311 lb·ft) 393 N·m (290 lb·ft)
RPM 4,400 4,000

Official Japanese site:

American site:

[edit] See also

[edit] Footnotes

[edit] External links

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