Category Archives: Turbo

22b: First generation Impreza WRX STi special variants

22bRare japanese widebody STi
22b STi

Japanese special variants

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.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. Note: internal Subaru material states the block comes from a V3 EJ20G NOT the EJ22G as most think. Also the intake manifold and heads were from the V4 EJ20K. 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 (260 kW; 350 hp) 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 cast on the brake calipers and painted white.

2004 – 2007 USDM STi breakdown

2004 – 2007 USDM STi breakdown:

A Stock 2005 USDM STi
A Stock 2005 USDM STi

Rev. D (2004)

In 2004, Subaru of America announced it would sell the WRX STi. Subaru Tecnica International’s president said in an interview with Road & Track magazine that he wished to beat the Mitsubishi Lancer Evolution in the US. Thus, each iteration of the US-spec WRX STi is essentially the same as the respective J-spec STi Spec C. All part numbers matched 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

2004 – 2007 USDM STi breakdown:

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 front LSD in the 04 model was replaced with a helical unit, the rear differential remains the same clutch type unit. Torque split is set at 35/65. 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.

2004 – 2007 USDM STi breakdown:

Rev. F (2006)
The US-spec STIs receive the same face lift as the Japanese-spec STIs. Mechanically speaking, the DCCD (Driver Controlled Center Differential) 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 (NASIOC), 2006 owners have had issues with these plastic engine mounts.

The manufacturer will replace them, under warranty, if broken, with the 2005 rubber and metal mounts. Later 2006 vehicles were equipped from the factory with 2005 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 2006 STI weighs approximately 3,350 lb (1,520 kg).


Impreza WRX STi
Third generation STi

Third generation (2008-present)
Third generation (GR)
Production 2008-present
Body style(s) 5-door hatchback
4-door sedan(2011-)
Engine(s) 2.0L 304 hp (227 kW) H4
2.5L 305 hp (227 kW) H4
Transmission(s) 6-speed manual
5-speed automatic (w/SPORTSHIFT manual mode) (Japan, Hong Kong, Singapore, Indonesia, and Australia only)
Wheelbase 103.3 in (2,624 mm)
Length 173.8 in (4,415 mm)
Width 70.7 in (1,796 mm)
Height 58.1 in (1,476 mm)
Curb weight 3,373 lb (1,530 kg)
Related Subaru Forester
Subaru Impreza
Subaru Impreza WRX

Subaru Impreza WRX STI 2008The 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 hatchback, and has different fenders that are 2.2 in (56 mm) wider. It adopted “Subaru Intelligent Chassis Design” and “Dynamic Chassis Control Concept”. The turbo forces air through a larger top-mount-intercooler which has lost the red “STI” that was on previous generations. It is the first generation of this model with an automatic transmission which is able to import to outside Japan.

Like other 2008 Impreza models, the 2008 STI benefits from a lower polar moment of inertia due to smaller overhangs, and also features a double wishbone rear suspension.[16] The car also borrows new intake and exhaust components from the Legacy GT platform.

The latest Impreza WRX STI features Multi-mode Vehicle Dynamics Control (VDC) with “Normal”, “Traction”, and “Off” modes, Subaru Intelligent-Drive (SI-Drive) with 3 modes: Intelligent, Sport, and Sport Sharp (S#), and Multi-mode Driver’s Controlled Centre Differential (DCCD). The DCCD enables driver to select the manual or auto: “auto”, “auto+”, and “auto-” mode in order to distribute the torque based on driving preference or conditions.

Subaru Impreza WRX STI (Japan)The JDM version has a 2.0L 308 PS (227 kW; 304 bhp) EJ207 engine with a Twin scroll turbocharger, while other versions of the car have a 2.5L 300 PS (221 kW; 296 bhp) EJ257 engine with a single-scroll VF48 turbocharger.

GC8 the first generation Subaru Impreza WRX STi

GC8 the first generation Subaru Impreza WRX STi:

Photo Credit: Barry DufekPhoto Credit: Barry Dufek
Photo Credit: Barry Dufek /

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.

First generation (GC8)
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)

There were six versions of the GC8 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 GC8 2DD, with the 2 representing 2-doors.

Version I (10/92 – 08/94) – GC8 A/B
The first STi was known simply as WRX 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, 228 ft·lbs) at 3500 rpm and weighed 1230 kg (2,710 lb). Before the STi, the highest trim line 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[6] 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, 235 ft·lbs) 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 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.

EJ257 Block info

So you bought an EJ257 block to build on the side. The seller says it’s “good” and “was running.” I mean, they can say anything, right? That is until you pull the engine block apart and the crank suffered major rod bearing damage from either oil starvation or debris from other failing components.

Here we go to look at the bore housings of the main bearings on the engine block. They look perfectly round to the eye but only measuring tools will reveal how oval they really are. Heat isn’t your friend and is the major cause in warping the bore housings. Rod bearing failure will cause excessive heat if driven on. Even brand new blocks from Subaru can be out of round.

The pictures show the honing marks after a pass on the honing machine. You can see where the color is more dull and has minimal light reflection. There was no contact there with the honing stones. You can see the dark defining line, which was where the bearing sat. Half of the bore housing number 3 (middle) didn’t make contact while honing as with bore housing number 4, which did not make any contact except where the block halves met.

What do we do now? The issue here is you’ll have bearing clearances that are too small or too large. This will cause oiling issues to areas where they most need it. Also the warped mains will not be straight. This can cause bearing to crank journal contact. So when looking at a block to buy, ask about the block’s history. If the seller has the block apart, look for yourself before purchasing. An experienced machine shop that has an align hone machine will be able to straighten the bearing housings as long as they aren’t too out of round.

EJ257 honing Marks
EJ257 honing Marks
EJ257 honing marks
EJ257 honing marks

5spd Subaru WRX five speed manual tips and tricks

5spd Subaru WRX five speed manual tips and tricks:

So you’ve got this noise coming from your 5spd transmission. It is starting to whine when you’re on/off the throttle. The sound seems to come right from below like around the shifter area. You may be a victim of the infamous falling apart center differential!

Don’t be too worried, transmissions are a dime a dozen! You still have the option to go 6spd or another 5spd transmission with different gear ratios if you choose.

 5spd: The damage. Most times the rear cover will back out minor like this photo. Other times it will completely come off. You can see the circlip survived this incident.
5Spd: The damage. Most times the rear cover will back out minor like this photo. Other times it will completely come off. You can see the circlip survived this incident on this WRX

World Rally Championship BOV/Anti-lag system

Sometimes if you spent more than five minutes posting facebook and instead searched on google you might understand the World Rally Champion anti-lag system that’s used on Subaru’s rally cars.


 It gets to a point were none of these people should own a turbocharged Subaru. True anti-lag systems are expensive and require extensive tuning and kills turbos which translates into a lot of money which none of these people have.

Subaru,Turbos, Blow off valves, and You

When someone first buys a turbo Subaru they are excited to modify their new toy. Often they’ll buy a exhaust, a intake, and a aftermarket blow off valve that replaces the factory BPV. Unknown to them Subaru’s often need to be tuned after even a little change like installing a intake or in this case installing a blow off valve.

If this guy took all of two seconds to type into google”Subaru blow off valve” he could have had all the answers he ever needed. Message boards like IWSTI or Nasioc have extensive stickied threads on this exact topic from people who are experts with turbo subarus.

Now he has to deal with people trolling him and people that are as clueless as he is. After a week or two he’ll probably ignore all advice and install it anyways. Two weeks after that he’ll be asking why he engine is knocking. Said person will complain that he bought this car with a loan and doesn’t have any money to get a new engine nor has the skills to build his own.

Facebook misinformation
Facebook misinformation