Category Archives: Tuning

Ej20, ej20G, EJ257, exhaust, gc8, Intake, Intercooler, JDM, STi, Subaru, TMIC, Tuning, Turbo, UK, USDM, WRX

Wastegate and Boost Creep FAQ

Wastegate and Boost Creep FAQ

What is Boost Creep?

Boost creep is a situation where your wastegate port is not large enough to allow the exhaust gas to bypass the turbo. What happens is the exhaust gas will choke the wastegate port preventing further gas flow through the port. Then, the exhaust gas has to take the path of least resistance which is through the turbine of the turbo. This will spool the turbo ‘uncontrolled’ beyond your normal controlled max boost level.

Wastegate and Boost Creep FAQ: A stock Subaru turbo.

The turbo will be spooling past wastegate spring rate pressure even though the wastegate is fully open thus it is uncontrolled. The best way to check for boost creep is to connect the turbo outlet port directly to the wastegate actuator port and go for a drive. In 4th gear you should normally get a stable boost level of about 0.5 BAR, if you have boost creep the boost will hit 0.5 BAR and will continue to rise with rpm until you either back off or hit overboost fuel cut.

Boost creep should only be present on a turbo that has very little restriction. For example a fully de-catted and high flow induction. It’s been found that the fast spooling IHI VF35 is very prone to boost creep. The cure is to remove the turbo and enlarge the wastegate port. Then, fit a stronger actuator 0.75 BAR the reason for this is because you have made the wastegate port larger. The effective size of the wastegate plate acting against the exhaust gas flow is larger which allows the exhaust gas excert more force on the wastegate plate.

This in effect weakens the effectiveness of the actuator. Before the increase in size of your wastegate port the actuator would open at 0.5 BAR, after the increase the actuator would open earlier at 0.3–0.4 BAR. After these changes are made to the turbo either a boost controller or a remap (to adjust solenoid duty cycle) should be sought to control the boost to a safe level.

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AWD, Drivetrain, Impreza, Subaru, Tuning, WRX

Stainless Steel Brake Lines install 02-07 WRX/STi:

Stainless Steel Brake Lines install 02-07 WRX/STi:

This is a step by step guide on installing stainless steel brake lines on your 02-07 WRX/STi.

1.) Get the car safely in the air and remove the wheels.

Stainless Steel Brake Lines: Get the front of your Subaru Impreza up on jack stands.

2.) Start with the front wheel. First thing to do is clean all the fittings that will be loosened to prevent dirt from getting in the stainless steel brake lines. Use compressed air then some brake cleaner to do the job.

3.)Then, remove the 12mm bolt holding the line to the strut.

Stainless Steel Brake Line: Remove the 12mm bolt holding the line to the strut.
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AWD, STi, Subaru, Suspension, TMIC, Tuning, WRX

Strut Tower Brace front install WRX/STi

Strut tower front brace install WRX/STi:

This strut tower brace guide should work on both 04 and 05’s just fine (mine is an 05). I’m not sure about the 06s’ since they relocated the AC line and it looks like Whiteline makes the only strut bar that will work on an 06. A little bit of modification with the 06+ model cars might be necessary. These are also specific to the JDM Spec-C Titanium Strut Bar but should work as a general guide for any strut bar on an STi.

1.) Remove alarm horn bar from passenger strut tower bolts which are 12mm. Disconnect the horn and put it aside for now. We’ll screw the horn into the side of the strut tower once we’ve installed the strut bar.

Strut tower brace: Removing the alarm horn bracket. Some models did not come with the alarm horn option so you do not need to do this.

2.)Lower the AC line bracket down a screw. This is the AC Bracket you need to unscrew (use a philips head screw driver or 10mm ratchet). You’ll need to remove the bolt that connects the AC line to the bracket and also the bracket where it connects to the firewall. Remount the bracket down a screw by mounting the upper hole where the bottom screw hole on the firewall is. The bracket is the copper colored metal piece.

Strut Tower Brace: Remove the copper bracket off of it’s mount on the firewall.

3.) Install Strut Bar.

First remove the bolts holding the struts to the strut walls. Bolts are 12mm. They should come off pretty easily since they are only torqued down to 14.5ft-lbs.

I found it was easiest to unscrew the strut bar into 3 pieces, the 2 parts that connect to the strut tower and then the actual bar itself (bolts/screws are 12mm). I put the round strut tower parts on first and loosely bolted them down. Then I placed the strut bar on top and loosely screwed down the strut bar to the strut tower connection pieces.

Strut tower brace: Passenger side strut bar end installed.
Strut Tower Brace: Driver’s side strut bar end installed.
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2.5RS, Ej20, EJ257, Intake, Intercooler, STi, Subaru, TMIC, Tuning, Turbo, WRX

Pitch Stop Install on Subaru WRX/STi

Pitch Stop Mount Install on Subaru WRX/STi:

This is a step by step guide on how to install an aftermarket Pitch Stop Mount to your 02-07 Subaru WRX or STi.

Pitch Stop Mount: In the foreground a oem plastic pitch mount and in the background a Perrin Performance pitch stop mount.

1.) Locate and remove the three 10 mm Gold colored bolts that secure the black vacuum lines to the bottom of the intercooler. You will need a shallow socket as it gets tight around the BOV. Careful not to drop them into the engine bay, it will be a PITA to find and retrieve them.

2.) Locate and remove the two 12 mm bolts that secure the recirculating BOV to the bottom of the intercooler. Again be careful not to drop these into the engine bay as it’s a jungle down there and it will be a PITA to retrieve them.

3.) Locate and remove the two 12 mm bolts that secure the intercooler to the engine. These are located one on each side of the intercooler.

4.) Now the intercooler is only held in place by the rubber intake hoses with the clamps. The one that is on top, from the intercooler to the throttle body/intake manifold is easier so do them first. Using the Flat head screw driver or an 8 mm socket loosen the clamps holding the intake piping to the Intake manifold and intercooler. And leave it for now.

5.) This is a little tough to do, but its not impossible. You should be able to do it even if you have large hands. Using the flat head or 8 mm socket, loosen the clamp that holds the intake tube coming from the cold side of the turbo to the intercooler. This is located underneath the intercooler.

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STi, Subaru, Tuning, Turbo

Deatschwerks injectors install on Subaru STi w/ a FMIC

Deatschwerks injectors install on a Subaru STi w/ a FMIC:

We put together this DIY since there are some more specifics when working with the  Deatschwerks injectors on a 2006 STI with a FMIC. YMMV and as with all DIY’s, you do this at your own risk. I will not be responsible for any damage you incur doing this yourself. (but seriously, it really wasn’t ‘that’ hard.)

DeatschWerks Injectors: Install

Tools you need:
– 1/4″ Ratchet
– 1/4″ 6″ extension
– 1/4″ U-Joint/Wobble adapter
– 10mm Socket
– 12mm Socket
– 12mm open/box wrench
– 12mm ratcheting box wrench
– T-25 Torx Bit or driver
– side/wire cutters (for removing zip-ties)
– long nose pliers (for opening hose clamps)
– wood handled rubber mallet (round handle)

Optional (nice to haves)
– Magnetic Tray (to keep from losing bolts/screws/etc)
– “Antenna” Magnet (to get ‘dropped’ bolts/screws/etc)
– rags for cleaning up spilled anti-freeze

Provided by Deatschwerks injectors:

02J-00-0740-4 Set of 4 740cc Side Feed Injectors for Subaru STI EJ25 04-06, Legacy GT EJ25 04-06, Impreza 2.5RS 97-98

DeatschWerks Top Feed 1000cc Injectors for WRX/STi/LGT

DeatschWerks  (02J-00-1100-4) 1100cc/min Fuel Injector, (Set of 4)

1. Let the car sit overnight or relieve the fuel pressure by unplugging the fuel pump (green plug in upper right area of passenger footwell). (NOTE: I just let my car sit overnight)

Deatschwerks injectors:

2. Start on the driver’s side (it’s easier).

a) Remove negative battery terminal.

b) Remove the two 12mm bolts holding in the plastic bracket to the intake manifold and clip the two zip ties keeping the harness in the plastic bracket.

c) Now remove the plastic bracket (it will take a patient/creative rotation to get it out from the hoses/harnesses) and you’ll be able to clearly access the torx screws holding down the little bracket that holds down the injectors.

1.You may also want to unplug the blue connector and the Crankcase breather hose (regular clamp, not the crimped one) to provide maximum access to the injectors.

d) Unplug the injector, remove the torx screw (Proper size Torx Bit: T-25), swing the bracket up and out of the way, and pull the injector out. You will need a small screwdriver with a sharper tip to pop the injector up. Just be careful not to damage the injector seat or the injector housing / Rubber O-ring

3. Now, get one of your newly purchased Deatschwerks injectors. Open the tube of Super Grease (should be provided) and generously lube the lower O-Ring, and moderately-sparingly lube the upper O-Ring. ONLY LUBE the O-RINGs, try not to get lube on the injector screen or filters

4. Gently insert the Deatschwerks injector. You will want it to sit on the upper O-Ring, flush to the injector port. Then use the bottom of rubber mallet wooden handle to push the Deatschwerks injector in until it seats. There will be a noticeable but gentle “pop” not a sound but a “feel” once the Deatschwerks injector seats. If there is a fair amount of gas left in the injector port, it may even just slip in … no “pop” feeling.

5. Once you have the deatschwerks injectors seated, just reverse the steps in #2

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

Flywheel: Flywheels for Subaru WRX/STi’s FAQ

Flywheel FAQ:

How does a lightweight flywheel improve performance? A transmission can be thought of as a fulcrum and lever in a car. First gear has a really long lever; second gear has a shorter lever, etc. The lever represents the mechanical advantage that gears give your vehicle. When your car is moving, you have two factors that are present during acceleration, one is driveline losses, which are constant and the variable, which is vehicle weight and the mechanical advantage supplied by each gear.

Flywheel: SPEC flywheels are CNC manufactured at an unheard-of .001 tolerance, in an industry where the standard is .010. This precision manufacturing process ensures perfect balance and a perfectly flat bedding surface for the clutch disc, both of which also contribute to the ultimate in safety for competitive environments. All SPEC flywheels carry SFI certification.

While changing to a lighter flywheel will give the user little to no changes on a dyno, the apparent changes are quite dramatic due to the greater mechanical advantage. Consider these made up figures for consideration: Drive line losses, 45 pounds and vehicle mass (weight) at the driveline (remember your gear’s mechanical advantage reduces your actual car weight). We know that within reason, vehicle mass is a constant.

Now imagine if you reduced the driveline loss from 45 to 35 with the use of a lightweight flywheel. Since the engine has less drivetrain losses to compensate for, this means the “gained” horsepower can be applied to moving the vehicle mass. Using mathematics, one can realize that the higher you go up in gears, the less effect that a lightened flywheel will have to the overall equation.

Are there any downsides to a lightweight flywheel? While the performance characteristics of a lightweight flywheel seem to be the perfect solution, there are compromises:
a. Low end performance is affected. This usually means that higher revs are necessary for smooth starts due to the reduced rotational mass. For drag racers, this can be a BIG issue.
b. Possible missfire check engine light.
c. Possible chatter, like missfire this affects some users and not others.

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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.

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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