Subaru WRX STI: Boxer on all Fours

The Subaru Impreza WRX and WRX STI (more recently called Subaru WRX and Subaru WRX STI without the Impreza name) are high-performance sport compacts based on the Subaru Impreza lineup.  The WRX name can either stand for “World Rally Cross” (WRC) or “World Rally Experimental”.  In any case, this name is an indicator to Subaru’s position in the world rally-racing stage.

The WRX debuted in Japan in November 1992, hot off the heels of the then-all-new Impreza (the successor to the Leone in the compact segment).  While the Impreza was designed for a front-drive setup, all-wheel-drive (AWD) was utilized in some other models, such as the Outback wagon and WRX.  Engine options for the Impreza varied in size, ranging from 1.5 to 2.5 liters.  Since the WRX was exclusive to Japan, North American Imprezas didn’t get a WRX variant.  Thus, these models were stuck with the 1.8L EJ18 (officially EJ181) developing 110 horsepower.  The Japanese-market GC8 WRX was initially installed with the 2.0-liter “EJ20T“.  In actuality, this engine was designated EJ20G, and was a turbocharged 240 horsepower boxer-4 (H4) unit.  This engine was equipped with hydraulic lifters as opposed to the Legacy’s same engine which had rocker arms.  Power was delivered via a viscous center differential and viscous rear limited-slip differential.  After the debut of a slightly-stripped variant called WRX RA, Subaru Tecnica International (STi) developed an even more potent WRX.  February 1994 saw the debut of the WRX STI, which now threw 250 horsepower.  The STi was a complete Impreza/WRX that came fresh off the assembly line, and then stripped down and modified with STi components.  This was the GC8C, or “Version I“.  November 1994 saw a power increase to 260 horsepower for the WRX.  A limited hatchback Impreza with the WRX engine, called “Gravel Express“, was produced.  The STI got a power boost to 275 horsepower and gained gold wheels akin to its rally-racing counterpart.  October 1995 saw the debut of “Version II” in the STI lineup.  New that year were the WRX V-Limited and WRX Type RA STi.  These models commemorated Subaru’s success in world rally racing, and deleted some curb weight.  Some V-Limited models got radio and AC as standard equipment.  Subaru produced 555 examples of the WRX Type RA STI Version 2.

September 1996 saw a redesign to the Impreza WRX STI.  New to the lineup was a 2-door coupe called WRX Type R STi.  The 2.0-liter boxer four was an updated version called EJ20K, which could produce a maximum of 280 horsepower.  Compared to the sedan, the Type R coupe was lighter, stiffer, and had a close-ratio transmission with a harder shell.  The Type R was a limited-time offer rather than a mainstay, and only 10,000 are estimated to have been produced exclusively for Japan.  March 1998 saw the release of the even-rarer 22B coupe, which was made to commemorate Subaru’s continuous victories in the World Rally Championship.  The 22B STi was a lower-slung widebody coupe, which utilized a unique 2.2L EJ22G, which featured forged pistons and a cylinder head similar to that on the EJ20K.  Other modifications included 17-inch wheels, Bilstein shocks, red brake calipers, and a twin clutch system.  These models sold like hotcakes until the end of the 22B’s production in August that year.

1999 Impreza WRX STi coupe

The GC8F series was introduced in September 1998.  The WRX/STi were facelifted in conjunction with the rest of the Impreza lineup.  There was also a slight mechanical change: the EJ20K (eventually to be the EJ207) was an upgraded “Phase 2” engine.  This generation saw the release of the limited-run WRX Type RA STi Version 5.  September 1999 saw the release of the final GC8G series; which, mechanically, was not too different from the GC8F.  However, the car was flared out for a slightly more aggressive appearance.  In 2000, Subaru exported 1000 WRX’s to the UK to be customized by their British motorsports division, Prodrive.  These models were the WRX P1, which were based on the JDM Type R coupe.  Performance enhancements included four-piston front brake calipers, electric Recaro seats, 18-inch wheels, and a suspension system optimized for British roads.  Meanwhile in Japan, another limited lineup, the S201, was released.  This model utilized every part of the STi parts catalog, ranging from its large front splitter to its massive rear wing.  This contributed to a truly racecar-esque appearance.  One mechanical tweak to the S201 was the 300 horsepower output from its engine – 20 more horsepower than was necessary for most typical JDM sports cars.  Only 300 such models were produced.

August 2000 saw the debut of the second generation GD.  The first performance variant of this generation was the WRX sedan, followed by the WRX STi, Type RA STi, and WRX STi wagon.  The standard WRX was powered by an IHI-turbo’d EJ205, good for 250 horsepower and 246 ft/lbs.  Late 2001 saw the release of the lightweight WRX STi Spec C, which had lighter body panels, lighter glass, increased wheel caster and wheelbase.  This drastically helped aid in handling and performance.  Another benefit to the Spec C was its transmission, which had its own oil cooler.  This first pre-facelift Impreza would retain its “bugeye” appearance until late 2002.  In 2004, Subaru introduced the WRX WR-Limited, which sported STi bodywork.  It featured an STi-inspired front bumper, rear spoiler, and gold Rays wheels.  This was similar to the US-market STi which debuted that year, right after the North American debut of the Mitsubishi Lancer Evolution.

The entire Impreza lineup received a “hawkeye” cosmetic refresh in 2005.  The WRX got the same rear-spoiler treatment as its big-brother STI, as well as viscous rear LSD; the STI and Spec C both got the same increased wheelbase and wider 8 inch (203 mm) wheel rims.  For increased stability, the Spec C was outfitted with Arai dampers, 21 mm anti-roll bars, and reinforced strut towers.  To reduce engine noise in the passenger compartment, Subaru decided to swap the metal engine mounts with those made from liquid-filled plastic.  November 2006 saw the release of the final special edition Impreza for this generation.  The Spec C Type RA-R put an emphasis on track use, and had specially designed 235/40 R18 tires as its footwear.

Own work.

April 2007 saw the world premiere of the third generation WRX alongside its base counterparts at the New York International Auto Show.  The STI variant debut in October of that year.  This generation rode on an increased wheelbase (2620 mm) and the sedan was longer in exterior dimensions (4580 mm versus the hatchback’s 4415 mm).  Power for the WRX and STI came from different sources: The WRX was equipped with the turbocharged 2.5L EJ255 throwing 225 horsepower, and the Japanese-market STI was powered by a turbo 2.0L EJ207 developing 308 horsepower.  The rest of the world got a 300 horsepower 2.5L EJ257 in their STI’s.  In 2008, Subaru produced a limited-edition 20th Anniversary Edition WRX STI based on the hatchback.  Exclusive to the Japanese market, this model featured specially-tuned shocks and springs, anti-roll bars, 18-inch aluminum wheels, Recaro seats with red stitching, and commemorative plating on the center console.  Only 300 such models were produced.  In 2009, the Impreza gained a cosmetic update for the 2010 model year.  Also new were the STI Spec C and A-Line.  Initially available only in Japan and Singapore, the A-Line was an automatic-transmission version of the WRX STI, which featured a steering-wheel mounted semi-automatic paddle shifter.  Model year 2010 saw the North American release of the WRX STI Special Edition, which resembled the JDM Spec C.  For better handling, the Special Edition was fitted with thicker stabilizer bars and 18-inch alloy wheels.  Creature comforts were limited: The interior featured only manual A/C and a four-speaker audio system.

A 2014 WRX STI at a local car show.  Own work.

2011 saw the release of the limited-edition WRX STI S206 and S206 NBR CHALLENGE PACKAGE.  Both received many STI-derived parts, but also gained Recaro bucket seats, a unique carbon-fiber roof, and carbon rear spoiler.  Just like the 2008 20th Anniversary Edition hatchback, only 300 examples of this model were produced.  In 2012, Subaru made a few more improvements on the WRX STI, Spec C, and A-Line Type S.  The STI gained some A-Line equipment, such as a premium tan interior and forged alloy BBS wheels.  The Spec C was now available as a 4-door sedan, but got a rear spoiler delete.  These models had 17-inch wheels and optional A/C.  In 2013, Subaru released their final special editions for this generation, the WRX STI tS Type RA and WRX STI tS Type RA NBR CHALLENGE PACKAGE.  Sales ended in August 2014.

A 2015 WRX at the 2015 VIAS.  Own work.

For the fourth generation, Subaru took a different turn in producing the high-end WRX and WRX STI lines. These models, with the chassis code VA, gained their own slot in the Subaru lineup. Although much of the bodywork was shared with the base Impreza, the WRX boasted other features and a more aggressive fascia unique to itself. Thus, the WRX remains separate from the Impreza lineup. The base 4th-gen Impreza (GJ/GP) began production in 2011, whereas the WRX and WRX STI debuted for 2015.

Powering the WRX is the 2.0L twin-turbo FA20F, which produces 268 horsepower and 258 ft/lbs of torque. This is the same engine used in the Forester XT (250 hp USDM) and is a variant of the naturally-aspirated FA20D used in the Subaru BRZ/Toyota 86. Performance aids include the twin-turbo units mounted lower in the engine bay to help reduce the car’s center of gravity, as well as a higher compression ratio of 10.6:1. Although both the previous EJ-series engine and the FA20 have a redline of 6700 rpm, the latter has the advantage over the former in that the higher compression ratio provides a wider torque peak. Although a 6-speed manual could be paired up, Subaru introduced a new CVT with paddle shifters.

Own work.

As to be expected, the WRX STI is a much more potent version of the WRX. Besides the cosmetic upgrades such as a large rear spoiler, the STI is powered by either a 2.0L EJ207 or a 2.5L EJ257. While Japan got the smaller EJ20 unit, the North American STI has the 2.5-liter, which throws 305 horsepower; up 5 horses from the previous generation. Model year 2018 saw the release of the limited-run WRX STI Type RA. Improvements in performance include increased power (310 horsepower), recalibrated transmission, 6-piston Brembo brakes, carbon rear spoiler, and weight reduction. The driver could be seated in a Recaro seat with STI stitching embedded into it. Only 500 examples of the Type RA were sold.