All posts by Subaru Idiot

AWD, Ej20, EJ257, STi, Subaru, Tuning, Turbo, USDM, WRX

Clutch: Subaru WRX/Sti clutch FAQ

Clutch: Subaru WRX/Sti clutch FAQ

The first impulse when clutch shopping is to get “too much” clutch. This is often a very big mistake, as there will be compromises in the different types and compositions of clutches.

Clutches hold Torque, not Horsepower:
Most performance enthusiasts relate more to horsepower numbers rather than torque, but clutch capacity is measured in terms of torque. Think in terms of a high rpm 250 HP Honda Civic versus a 250 HP Ford Powerstroke turbo diesel. The truck will need about three times the clutch capacity because the engine produces about three times the torque.

Choosing what’s best for you:
It may be difficult to know what clutch is right for a particular application since there are so many different levels of personal tolerance and many variations in design. Some people can tolerate clutch chatter, or noise, or heavy pedal effort, or shorter clutch life, higher cost, or other trade-offs. But why tolerate unnecessary issues if you don’t have to? Get the clutch that suits your needs.

What are the various clutch materials? Other than unique or specialized compositions, clutches are generally comprised of:

1. Organic
2. Kevlar
3. Ceramic
4. Feramic
5. Carbon (initially invented in 1998 by Alcon Components for the Subaru World Rally team )
6. Sintered Iron

Depending on manufacturer specifications, this list also shows the general order of the amount of force the clutch materials can hold.

Organic: Metal-fiber woven into “organic” (actually CF aramid with other materials), original-equipment style. Known for smooth engagement, long life, broad operating temperature, minimal-to-no break in period. Will take hard use, somewhat intolerant of repeated abuse (will overheat). Will return to almost full operational condition if overheated. Material is dark brown or black with visible metal fibers.

Kevlar: High-durability material more resistant to hard use. Engagement is similar to organic, but may glaze slightly in stop and go traffic, resulting in slippage until worn clean when used hard again. Higher temp range in general, but can be ruined from overheating; will not return to original characteristics if “cooked”. Material is uniform yellow/green and may look slightly fuzzy when new.

Ceramic: Very high temperature material. Engagement is more abrupt. Will wear flywheel surface faster, especially in traffic situations. Due to it’s intrinsic properties, ceramic has a very high temperature range. Material is any of several light hues – gray, pink, brown.

Feramic: This unique clutch material is one that incorporates graphite and cindered iron. The result is a friction material that offers good friction coefficient, torque capacity, and smoothness of engagement.

Carbon: Very high temperature material. Engagement is more abrupt. Will wear flywheel surface faster, especially in traffic situations. Slightly more durable and flywheel-friendly compared to other aggressive clutch materials. Material is black.

Sintered Iron: Extremely high temperature material. Engagement is extremely harsh and is generally considered an “on/off switch” both due to it’s characteristics and the clutch types this material is generally associated with. It requires a special flywheel surface. Material is metallic gray in color.

 

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Ej20, EJ257, exhaust, STi, TMIC, Tuning, Turbo, USDM, WRX

Uppipe WRX upgrade FAQ

Aftermarket Uppipe FAQ for WRX/STi

Uppipe: The primary purpose of an aftermarket uppipe is to remove the catalytic converter housed within the stock unit. This serves two purposes: to increase horsepower and decrease turbo spool time.

uppipeaftermarket
Uppipe: The primary purpose of an aftermarket uppipe is to remove the catalytic converter housed within the stock unit.

HP gain is around 10HP. This figure is highly debated as different manufacturers use different dynos with different cars with different levels of mods. Dyno Proof Example. The general consensus for turbo spool time decrease is boost will occur around 500 RPM sooner.

Is an aftermarket uppipe a performance or reliability mod? With regard to swapping over from a catted uppipe to a catless uppipe, it’s both. Need some evidence of the reliability? View this link.

Which manufacturer is best? This topic is highly debated. There have been no reported consistent “bad” uppipes on the market. Obviously, there may have been bad pipes sold, but not enough to report as “bad” overall.

What uppipe metal material is best? Uppipes are made from mild steel, stainless steel (304 & 321), cast iron, and inconel. There is no irrefutable evidence that one material is better than the other. Obviously, corrosion levels are higher with mild steel (coated or otherwise) and cast iron. Corrosion on cast iron, due to it’s thickness and material qualities, is more resistant to corrosion damage than mild steel. In terms of heat retention, the best material is inconel.

Which uppipe construction method is best? Uppipes are either solid or flex. There is no irrefutable evidence that one design is better than the other. The thought process is that a flex pipe will reduce the chances of leaking. Practical application has shown that correct installation plays a bigger role than the uppipe construction.

What is the cheapest uppipe? Gut your stock uppipe. Instructions. Gutting your stock uppipe can have the same benefits as using a more expensive aftermarket uppipe. Dyno Proof.

Which uppipe has the best gains? There is no irrefutable evidence that any uppipe has better gains than another. The consensus, if there is one, is they are all within 1-2 HP, gain wise, of each other.

Where do I buy an uppipe?

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

TGV Deletes for Subaru WRX/STi

TGV Delete on WRX/STi’s:

The primary purpose of a TGV delete is to remove the divider bar and butterfly valve inside the TGV assembly to improve airflow to your engine.

TGV Delete: Top is a deleted TGV and bottom is the stock TGV.
TGV Delete: Top is a deleted TGV and bottom is the stock TGV.

HP gain is 12 HP. This figure is highly debated as different manufacturers use different dynos with different cars with different levels of mods.

What is the purpose of TGV Deletes? The are meant to reduce cold idle emissions. Nothing more, nothing less. Once your vehicle is warm, the butterfly valves open fully and remain that way.

Which manufacturer is best? This topic is highly debated with no real winner in terms of performance. There are several companies that offer the TGV delete service as well as purpose built units or Japanese models which are, in essence, hollow units.

Japanese model, what is that? TGV internal assemblies are only used for cold start emissions on US cars. Hence, the Japanese TGVs do not have the divider plate or butterfly valves. Some models are one piece intake manifolds with longer runners that make up the TGV portion and other models are just like their US cousins with no internal plates or butterfly assemblies. Neither units have the associated TGV external motor controllers as well.

Which TGV Delete has the best gains? There is no irrefutable evidence that any TGV Delete option has better gains than another. The consensus, if there is one, is they are all within 5HP or less, gain wise, of each other.

Do TGV Deletes cause a CEL? Yes. By removing the TGV motors, it will throw quite a few CELs. The bad news with this, is the TGV CELs will throw your car into limp mode, meaning unlike some other CELs that you can still drive around with and have no fear, the TGV codes limit boost/RPM operation meaning they must be taken care of in order to drive your car for any reasonable distance.

How do I fix the TGV CEL? You have three methods:
1. Normally, you remove the TGV motors and the rod that holds the butterfly valves in place. You could leave the rod in place (sans butterfly valves) and reinstall the TGV motors. This would allow them to actuate normally making the system think everything is working correctly.
2. APS makes a block that you attach the TGV motors to, this allows them to actuate normally making the system think everything is working correctly. These are not sold separately though, but can occasionally be purchased in the Private For Sale Forum or on eBay.
3. Various engine management systems can remove the associated CELs.

Do I need to perform the CEL fix? Yes. The TGV CEL codes will throw your car into limp mode. This will limit boost/RPM seen by your vehicle. It will still drive, but it should only be driven a short distance with the TGV CEL. Meaning you can drive it across town or a few short trips, but by no means should you drive it as a daily driven car for weeks on end until you get the proper fix.

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AWD, Ej20, ej20G, Intake, Intercooler, JDM, Legacy, Rally, Subaru, TMIC, Tuning, Turbo, UK, wrc

Legacy: 1989-1994 Subaru Legacy (BC/BF) GT/RS

Prior to the Legacy RS turbo, Subaru had never enjoyed the experience of distributing a genuine performance car. Of course, there had been the 4WD turbo RX and Vortex, but neither could crack 10 seconds for the 0-100km/h sprint – although they were very reliable. The RS was the gun version of the first Legacy series released in 1988 and discontinued in 1994. The RS (Rally Sport) model was aimed squarely at world rallying, with many of its components and concepts carried over to the dominating Impreza WRX.

Legacy: The BC/BF is unique in having an Air - Water intercooler with a front mounted radiator for optimal cooling. The bonnet scoop only provides cooling to the turbo. While later model legacy's have all used air to air intercoolers.
Legacy: The BC/BF is unique in having an Air – Water intercooler with a front mounted radiator for optimal cooling. The bonnet scoop only provides cooling to the turbo. While later model legacy’s have all used air to air intercoolers.

The center Viscous LSD on the MT models initially starts out with a 50/50 torque split, front and rear, and will up the ratio towards the end with more traction. The manufacturer doesn’t give a final figure, so the max split is either 65/35, or could even venture as high as 95/5, since the A/T model has a different system that is marketed at a 65/35 maximum split. A higher ratio would explain some of the handling characteristics at the limit. The rear differential is also a Viscous LSD model.

The BC/BF is unique in having an Air – Water intercooler with a front mounted radiator for optimal cooling. The bonnet scoop only provides cooling to the turbo. While later model legacy’s have all used air to air intercoolers.

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Ej20, ej20G, EJ257, JDM, TMIC, Tuning, Turbo, USDM, WRX

Turbo: STi/WRX VF Series Turbocharger breakdown:

Turbo: STi/WRX VF Series Turbocharger breakdown:

IHI VF Series
The numbering on both the VF turbos are for reference purposes and not necessarily indicative of its ‘performance’. On GC8/GF8 WRX STi, the VF turbos have gone ‘smaller’ from VF22 to 23, 24, 28, 29 while the release of the New Age STi GDB saw the introduction of a new breed of VF turbos with a bigger compressor wheel namely, VF30, VF34, VF35 for example. The previous VF turbos (VF22,23,24,28,29) have been ball bearing cored while the later ones (VF30, VF35) are Divided Thrust Bearing type core, with the VF34 being a Ball Bearing.

IHI VF22
(455cfm at 18.0psi, 250-325whp, Bolt-On)
The VF22 has the largest potential for peak horsepower. In other words, in the IHI model range, the VF 22 supports the highest boost levels. With its significantly increased turbine housing, the VF22 turbo is capable of producing upwards of 310 whp* on an EJ20. The downside of this turbo is the older center cartridge design and larger compressor housing, which makes for slower spool up but more top-end than the other VF series turbos.

This turbo is the best choice for those who are looking for loads of top end power. The top end power however, does not come without a cost. The VF22 spools significantly slower than the rest of the IHI models due to the larger P20 exhaust housing and is much less suited for daily driving than some of the other models. Although the largest VF series turbo, the VF22 is not quite optimal for stroked engines or those who wish to run more than 20PSI of boost.

The VF22’s compressor is rated at 35 lbs/minute. The VF22 was designed with the EJ20 in mind but because it has the biggest turbine in the IHI family it can be use on the EJ25 with a slight increase in performance. The VF22 is good for around a realistic 300 to 315 WHP on a 2.0L. The IHI VF-22 turbo is the largest of the VF-series turbos.

VF22: The IHI VF-22 turbo is the largest of the VF-series turbos.
VF22: The IHI VF-22 turbo is the largest of the VF-series turbos.

IHI VF34
(440cfm at 18psi, 250-325whp, Bolt-On)
The VF34 is nearly identical to the VF30, with the same exhaust housing and compressor. However the VF34 goes back to the ball bearing design, and in doing so achieves full boost approximately 500RPM sooner than the comparable VF30. The VF34 is the most recent IHI design and as such costs slightly more than its counterpart.

Top end performance and maximum output are identical to the 30. The VF34’s compressor is rated at 35 lbs/minute but the turbo suffers from the same turbine restrictions found with the VF30. The VF34 was designed with the EJ20 in mind and will not have the same performance on an EJ25. The VF34 is good for around a realistic 290 to 305 WHP on a 2.0L.

VF34: The VF34 was designed with the EJ20 in mind and will not have the same performance on an EJ25. The VF34 is good for around a realistic 290 to 305 WHP on a 2.0L.
VF34: The VF34 was designed with the EJ20 in mind and will not have the same performance on an EJ25. The VF34 is good for around a realistic 290 to 305 WHP on a 2.0L.
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Ej20, EJ257, STi, Subaru, Tuning, Turbo, WRX

Timing Belt and Water Pump Replacement Subaru WRX/STi

Timing Belt and Water Pump Replacement Subaru WRX/STi:

Timing Belt and Water Pump Replacement is critical in keeping your Subaru WRX/STi in good condition and to prevent the valves from hitting your engine’s pistons.

Tools used:

3/8 Ratchet
1/2 Ratchet
10, 12, 14, 22mm sockets
short extension
Impact wrench or strap wrench (I used both on separate occasions.)
Torque Wrench
Small metal ruler to measure belt deflection.
Drain pan and funnel for the coolant.
Brake Kleen
Lots of paper towels/shop rags.
3/8 socket driver (very handy.)
Feeler gauges
2mm allen wrench
allen socket for the right camshaft (6mm maybe?)
C-Clamp

Timing belt kit and misc:


Gates TCK328RB Timing Belt Component Kit

Gates 42030 Water Pump

Gates 34012 Thermostat


NYPPD Billet Timing Belt Guide Subaru Impreza WRX EJ20 STi EJ25 2002-2013 Turbo

Genuine Subaru SOA868V9270 Super Coolant

Subaru SOA635071 OEM Coolant System Conditioner

Helpful tools:

Subaru Camlock Tool for Subaru 2.0L and 2.5L DOHC turbo engines C23-506

Subaru Crank Pulley Tool C23-503

Subaru STD Int/Exh Cam Sprocket Tool – similar to 499207400-A

Subaru Cam Sprocket Tool – AVCS Int C23-501

Go to the next page to get started.

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AWD, Ej20, EJ25, EJ257, Intake, Intercooler, STi, Subaru, Turbo, USDM, WRX

FMIC (Front Mount Intercooler) STi/WRX FAQ

FMIC: The primary purpose of a FMIC (front mount intercooler) is to reduce post turbo air temperature prior to entering the combustion chamber via the throttle body.

FMIC install in a Subaru WRX STi.
FMIC install in a Subaru WRX STi.

HP gain is around 15HP. This figure can vary as results can be further enhanced with post installation tuning. This is one modification that is extremely difficult to put a traditional HP figure on as results truly vary from car to car based on tuning and turbo output in terms of CFM.

Which manufacturer is best? This topic is highly debated. There have been no reported consistent “bad” FMICs on the market. Obviously, there may have been bad FMICs sold, but not enough to report as “bad” overall.

Which FMIC construction method is best? FMICs have two main construction methods:
1. tube and fin
2. bar and plate
There is much debate as to which construction method is best. There are many pros and cons with each design type, but no real hard data. Bar and plate designs are consistently reported as more damage resistant which gives them the edge with regard to appearance longevity. In the end, you are best advised to chose a FMIC based on other qualities rather than concentrate on construction design.

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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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