Category Archives: WRX

AWD, DCCD, EJ257, STi, Subaru, Tuning, Turbo, USDM, WRX

Transmission: STi 6-Speed basic swap info into a WRX

Front Differentials:
02-07 WRX: open
04 STi: “SureTrac” LSD
05-07 STi: “Helical” LSD

Transmission: Sti 6-Speed vs. WRX 5-speed
Transmission: Sti 6-Speed vs. WRX 5-speed

Rear Differentials: R160, R180
These were originally used in the Datsun 510, 610 and other IRS Datsuns. The “R” stands for Fuji Heavy Industries. The R180 was used in the front axle of Datsun 4×4 trucks (720, etc). The number represents the ring gear size in millimeters.

R160 – 52lbs. WRX rear differential. It has a viscous LSD which is no better than an open differential since the unit is so tiny in this differential.
02-05 have a 3.54 gear ratio
06-07 have a 3.70 gear ratio
R160’s on 2.2L Legacy/Impreza’s have a 3.9 gear ratio

R180 – 64lbs. STi rear differential. It has a mechanical clutch type LSD.
04-05 R180’s have a 3.90 gear ratio
06-07 R180’s have a 3.54 gear ratio

Center Differentials:
02-07 WRX: Viscous coupling type
02-05 has a 1.1:1 gear ratio
06-07 has a 1:1 gear ratio
04-07 STi: DCCD (Driver Controlled Center Differential)
04-05 has a 1:1 gear ratio
06-07 has a 1.1:1 gear ratio

Do I need different front axles?
02-early 04 WRXs have female axles and need to use stubs that go inside the transmission . Late 04-07 WRXs use male ended axles that slide inside the front differential so there is no need for stubs. For the female axles, you need axle stubs, circlips, and seals to reuse the WRX axles (check out the seal differences link for part numbers). You can use the stubs from your 5MT. For the male ended axles, they just slide right into place with the correct seals and circlips. 04 STi front axles will work too.

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AWD, STi, Subaru, Turbo, USDM, WRX

How to shift with AWD or a Manual Transmission.

How to shift with AWD or a Manual Transmission:

Where can I find good background information of transmissions? A good general reference for new people as well as a refresher for more advanced users is How Stuff Works’ Transmission Tutorial.

Where can I find good background information on differentials? A good general reference for new people as well as a refresher for more advanced users is How Stuff Works’ Differential Tutorial.

Shift: STi Shifter
Shift: STi Shifter

Is shifting different with an AWD car vs. a FWD or RWD car? One has to visualize the power transfer in a car to get a better understanding. In a FWD or RWD car, if you shift or launch the car too aggressively, the excess power is transmitted to the tire(s), which will spin. Put another way, excess power is “burned off” through tire smoke. In an AWD car, if you shift or launch the car too aggressively, the excess usually isn’t enough to overpower thetires’ grip. In this situation, the excess power must be absorbed somewhere else in the drive train. Though some drive train shock is normal, in an overload situation, excess power is transmitted to the various driveline components, which can accelerate wear and tear.

Where are the shifting differences most apparent? Starting off in first gear and the 1-2 shift are the most common causes of driveline shock. Obviously, there is reason to shift responsibly in every gear but these are the most commonly seen problematic shifting issues.

Is resting my hand on the shifter bad? From the WRX Owners Manual: “Do not drive with your hand resting on the shift lever. This may cause wear on the transmission components”. This advice should apply to every Subaru MT model. That being said, the safest course of action is to keep both hands on the wheel unless actually shifting.

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EJ257, STi, Subaru, Tuning, Turbo, USDM, WRX

Coolant use and Cooling System for Subaru WRX/STi

What type of coolant should I run in my car? You can never go wrong by using Genuine Subaru Coolant available through your local dealer.

Subaru Genuine Coolant. To the left Super Coolant and to the right long life coolant.
Subaru Genuine Coolant. To the left Super Coolant and to the right long life coolant.

Is the Subaru coolant pre-mixed or not? They have both kinds, but BE SURE to read the labels carefully as they are nearly identical in appearance except the wording on the package!

Is there a required coolant additive? Yes. Subaru Cooling System Conditioner has recently been required to be added with every coolant replacement to prevent coolant system leaks. This recommendation applies to every Subaru model for every model year.

Subaru Cooling System Conditioner has recently been required to be added with every coolant replacement to prevent coolant system leaks. This recommendation applies to every Subaru model for every model year.
Subaru Cooling System Conditioner has recently been required to be added with every coolant replacement to prevent coolant system leaks. This recommendation applies to every Subaru model for every model year.
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Ej20, EJ257, STi, Subaru, Tuning, Turbo, USDM, WRX

Spark Plug info for your Subaru WRX/STi:

Spark Plug info for your Subaru WRX/STi:

Refer to your owners manual for recommendations. Alternately, you can visit an auto parts store or online retailer for recommendations on suitable spark plugs designed for your vehicle. Major manufacturers are:
a. NGK
b. Bosch
c. Denso
d. Autolite
e. Champion

Sti spark plug location
STi spark plug location

Who are the specialty spark plug manufacturers? These manufacturers make specialty plugs that have unique compositions or designs that claim increases over traditional plugs. They are listed for advanced users or those with interest.
a. Torquemaster
b. Beru (specifically the Silverstones found here)
c. SplitFire
d. PREP spark plugs
e. E3 spark plugs
f. Pulstar plugs

What types are there? There are really three main types:
a. conventional nickel alloy (commonly referred to as “copper”)
b. platinum
c. iridium

Which type should I use? That depends on how often you are interested in changing the spark plugs. Conventional spark plugs generally last one year. Platinum or iridium can last, depending on manufacturer specifications, up to seven years.

What’s some good background spark plug information?

Materials: The three main types of spark plug materials are nickel alloy, iridium, and platinum. Copper can be used in the core all plugs.

All ground electrodes are made of nickel. The use of Platinum and Iridium, which are stronger, allow for much finer CENTER electrodes (the ground electrode is still Nickel). These finer electrodes do not quench the flame core as much as a conventional style plug. This increases ignitability, therefore increasing HP. It’s not a huge gain, but cylinder pressures are measurably higher.

Platinum or iridium can be used as a thin pad which is laser welded on the ground electrode (the “J” strap), this serves to increase the life of the plug.

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EJ25, EJ257, STi, Subaru, Tuning, Turbo, USDM, WRX

Pulley Subaru WRX/STi Rundown

The primary purpose of an aftermarket pulley is to reduce the size and/or mass of the stock unit. They serve two purposes: to reduce horsepower loss and increase throttle response. Notice the use of “reduce horsepower loss”. Pulleys DO NOT add horsepower, rather they free up horsepower due to the reduction of rotational mass.


Grimmspeed Lightweight Crank Pulley Black – Subaru All EJ Engines

A lightweight aftermarket perrin pulley.
A lightweight aftermarket perrin pulley.

HP gain is 5-10HP. These HP figures are a range as there have been very few before/after dyno runs with lightened or under driven pulleys.

What is a lightened pulley? Generally, it is an exact copy of the OEM pulley only CNC machined out of aircraft grade aluminum and powder coated for corrosion protection and aesthetic appeal.

What is an under driven pulley? This is a pulley that mimics the function of the OEM unit, but is smaller in diameter. This will reduce the duty cycle of the pulley and proportionally the parasitic drag on the engine.

Are under driven pulleys bad? It depends on the amount they are under driven. Some under driven pulleys can lead to reduced A/C output, lighting problems, stereo problems, and other voltage issues. Some are lightly under driven and some more so.

Isn’t replacing the stock harmonic damper (pulley) bad? Subarus do not come with a harmonic damper or balancer like some other vehicles do. For other manufacturers’ vehicles, this is a legitimate concern. Proof:

“Thank you for your patience as I checked with our Technical Services Department regarding your message below. They advised that the crank pulley is a pulley and nothing else. It is not used as a harmonic damper/balancer.

Thanks for the opportunity to be of assistance. If you need any future assistance, please feel free to contact us again.”

Best wishes,

John J. Mergen
Customer Service Department
Subaru of America, Inc.

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anti-lag, DCCD, EJ257, exhaust, idiots, Impreza, Intake, Intercooler, Ringland, STi, TMIC, Tuning, Turbo, USDM, WRX

Engine Management For Subaru WRX/STi

 

Why do I need engine management?

 


Consider your stock engine management for just a moment. Your stock engine control unit (ECU) is a very complex piece of circuitry that calculates hundreds of variables every second. All of these variables rely on inputs within a + or – range. When you modify your vehicle, these values change. As long as the changes are within the values the ECU expects to receive, your engine runs fine. Once the values are exceeded, the ECU is programmed to compensate to return the values to normal levels.

A typical way of engine management is to use a Cobb Accessport.
A typical way of engine management is to use a Cobb Accessport.

This is a layman’s explanation of how your stock ECU can actually work against you when modifying your vehicle. This also explains why modifications can feel great once they are bolted on but the butt dyno results seem to fade over time. This is due to ECU compensation.

What is the first step in finding what engine management I need? Finding a tuner. The Tuner FAQ will help with the general rules of finding a good tuner. Remember, it’s always better to have a custom tune vs. a plug and play or “staged” map. Always defer to the tuner’s advice as to what to choose as ultimately he will be the one to provide custom support. Discuss your goals and budget and your tuner should set you on the right path. If you are a “plug and play” kind of person, review the options below and decide for yourself along with input from locals in your regional forum and the car parts review forum.

What will engine management do for me? Generally speaking, engine management optimizes several engine functions to create more horsepower and efficiency. The stock ECU is designed to ensure your car runs fine and monitors the engine’s output parameters. Utilizing an aftermarket engine management solution takes this to the next level.

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AWD, gc8, Prodrive, STi, Subaru, TMIC, Turbo, UK, wrc, WRX

Prodrive GC8 WRX Special Editions

22B “Type UK”

In late 1998, Subaru UK officially imported 16 22Bs (described below), and passed them on to Prodrive for modification. The UK cars differ from the privately imported 22Bs, not just in their 3 year factory warranty, but with revised gear ratios more suited to UK roads.

This was achieved by changing the final drive ratio from 3.9 to 4.44 to lengthen the gearing. Cosmetically, the car got the headlights from the ‘99 model, UK rear light clusters and driving lights (not fog lights!) were fitted where the normal 22B has blanking plates. From the back, you can tell you’re looking at one of the rarest cars in the world by the “Type UK” and “Prodrive” stickers. The price was £39,950, and demand for the cars was overwhelming.

The rear of a Prodrive 22B Type UK.
The rear of a Prodrive 22B Type UK.

Interestingly, Subaru UK were not able to put their 16 cars through the Single Vehicle Approval scheme because the maximum of 50 privately imported 22Bs had already been registered in 1998. Consequently the Type UKs were registered in 1999. The cars do not meet European Type Approval regulations for noise and emissions.

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AWD, gc8, Rally, Turbo, UK, WRX

McRae UK WRX 1st Gen special editions

McRae UK WRX 1st Gen special editions

Series McRae

In June 1995, to celebrate their winning of both the manufacturers and drivers World Rally Championship titles, Subaru in the UK released a limited edition run of two hundred cars (numbered 1 to 201 – no number 13!) prepared by Prodrive going by the name of the Series McRae. The main improvements over the standard model are:

  • Special mica blue paintwork
  • 6.5 x 16 inch eight spoke gold Speedline Safari alloy wheels
  • Pirelli P Zero 205/50 ZR 16 low profile tyres
  • Recaro sports front seats with open headrests and Series McRae motifs
  • All seats (front and back) and door panelling retrimmed in Le Mans/Avus material
  • Factory fitted electric tilt and slide sunroof
  • Interior numbered Series McRae plaque
  • Side and rear Series McRae decals

On the road price was £22,999

A official Subaru WRX poster for the Series McRae.
A official Subaru WRX poster for the Series McRae.

Next page will be the Catalunya edition!

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