Category Archives: Intake

AWD, Ej20, EJ25, EJ257, Intake, STi, Turbo, WRX

Intake manifold bolts loose on a Subaru STi:

Video

Intake manifold bolts loose on a Subaru STi:

Don’t forget to tighten down your intake manifold bolts down to the correct torque values.

Intake manifold bolts loose on a Subaru STi: Make sure to tighten down your intake manifold bolts.
Intake manifold Subaru STi: Make sure to tighten down the bolts.

 

Otherwise you’ll end up with a broken sounding engine like this:

Luckily forgetting to tighten down the intake manifold bolts didn’t cause any permanent damage, but I wouldn’t go driving around like this either.

If you do TGV deletes like in this post. Make sure to use new intake gaskets where the TGV’s and the intake manifold meet up. What’s even more important is to make sure you tighten down those intake manifold bolts that hold the intake manifold to the TGV’s.

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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.
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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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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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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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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EJ257, Intake, Intercooler, STi, Subaru, TMIC, Turbo

Turbocharger: How to choose a Turbocharger

Turbocharger: How to choose a Turbocharger for your Turbo Subaru:

In order to make an informed decision when purchasing an aftermarket turbocharger, the consumer needs to avail themselves of the different types of turbochargers first. To this end, we will discuss the various types of turbos on the market. These are just the basics of turbo information though. Please do not confuse this as the main source for turbo information as there are many other factors to an informed turbo choice such as compressor maps, matching the turbo to your displacement, etc. For the best advice, please consult an experienced turbo vendor and/or your tuner.

A regular turbo is, in essence, a pump that forces air into your intake system. The end result is a denser air charge that will produce more power vs. naturally aspired vehicles. The only downside is that more power produces more heat, and the engine’s internal components must be properly suited towards turbo charging. Upgrading this unit to a larger one is the easiest route in terms of time, trouble, and expense. Common upgrades for all turbocharged Subaru models include the VF-30/34/22 and 16/18/20G.

A twin scroll turbo is designed to be used on an equal length exhaust set-up. By internal turbo design and having all the exhaust gases enter the turbo at the same time, this allows the turbo to spool faster vs. an equally sized regular turbo. This is a very important point as many people are confused by the marketing hype of twin scroll set-ups. When comparing a twin scroll turbo that will flow say 500 cfm vs. a normal 500 cfm turbo, the twin scroll should see full boost sooner. So if there are two suitably sized turbochargers, with one being twin scroll and one regular, the twin scroll unit may be your best choice if you do not mind the extra exhaust expense and prefer faster spooling.

This type of turbocharger requires more expense than a simple upgrade though. The biggest concern is the use of an equal length header, proper uppipe design, and the possible use of a different oil pan to accommodate the new twin scroll exhaust piping. Quirt Crawford of Crawford Performance recently did some testing on a GT32 twin scroll turbo Legacy to test the theory about the importance of exhaust flow to a twin scroll unit. When he switched from the correct equal length header and uppipe to a traditional unequal length header and normal uppipe, he saw degradation in turbo response by 750 RPM. This should be word to the wise to anyone who thinks they can avoid the expense of the correct exhaust components and still see the quicker spooling benefits of a twin scroll turbo.

Another consideration is the change in exhaust tone. An equal length header required in a twin scroll set-up sounds entirely different than an OEM or aftermarket unequal length header. To fans of the familiar boxer rumble, equal length headers are just not an option. It may sound silly, but for many, this reason alone is enough to keep them from buying a twin scroll turbo.

A rotated mount turbo is any turbo that’s physical size prevents it from fitting in the stock location and must be mounted at a slightly different angle. Most of the turbos that fall into this category are of the larger variety. Many require custom piping, a front mount intercooler, external wastegates, custom tuning, tumble generator valve deletes, and other technical or expensive upgrades to support it. Most would consider this type of turbo to be outside the scope of the average do it yourself person and should be farmed out to a professional or at least utilize one of the kits supplied by various manufacturers.

As well, many feel that when going this route, strong consideration should be given to fully built motor, or at the very least, forged pistons. Rotated mount turbos produce large amounts of power and though there is no magic horsepower number for switching to forged internals, the larger rotated mount set-ups seem to be commonly used on built motors.

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EJ257, Intake, Intercooler, STi, TMIC, Turbo

BOV: Blow off Valve Subaru FAQ

BOV: Blow off Valve Subaru FAQ

Term usage: “Blow off valves” go by several names, among them are compressor bypass valve (CBV), air by-pass valve, bypass valve (BPV), blow off valve (BOV), Diverter valve, and possibly a few others. BOV is the common and incorrect term that lumps true blow off valves and bypass valves under the same term. For the sake of correctness, this post will refer to either aftermarket BOV, aftermarket BPV or OEM BPV as these are the most correct terms.

What is the function of a blow off valve (BOV)? To release pressure from the intake tract of a turbo car when the throttle closes. It is a vacuum-actuated valve designed to releases the air to the atmosphere.

What is the function of a bypass valve (BPV)? To release pressure from the intake tract of a turbo car when the throttle closes. It is a vacuum-actuated valve designed to recirculate the air back into the intake before the turbo inlet, but after the airflow sensor.

A stock Subaru BPV (not a BOV).
A stock Subaru BPV (not a BOV).

What is the purpose of a BOV/BPV? When the throttle closes and the intake system is under pressure, the high-pressure air entering the motor will bump into the closed throttle plate, and in the absence of a BOV/BPV, a pressure wave will travel back to the turbocharger. The result is that the compressor wheel will stall (a phenomenon known as “compressor surge”) and slow down very quickly. This is hard on the bearings and decreases the turbo’s lifespan, but it also means the turbo will take longer to spin up the next time the throttle is opened.

Are aftermarket BOVs necessary with Subaru turbos? No. The OEM BPV is perfectly fine up to 20psi of boost. For applications using higher boost levels, an aftermarket BOV/BPV should be considered.

Can I mod my stock BPV to hold higher boost? Yes. I’ll be creating a post giving detailed instructions on how to do so.

Is the STi BPV better than the WRX BPV? No. They are the same. However, the JDM STi BPV will hold more boost as it is physically different than both the USDM STi BPV and the WRX BPV. The specific PSI rating of the JDM STi BPV is unknown, but users have reported it is good up to 25 PSI.

Is an aftermarket BPV better than the stock BPV? No. Unless you are considering an aftermarket BPV solely for the purposes of holding higher boost levels. An aftermarket unit should sound just like the OEM unit.

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Ej20, EJ257, Impreza, Intake, Intercooler, STi, Subaru, Turbo, WRX

Intake pipe turbo subaru FAQ

Intake Turbo Subaru

The primary purpose of an aftermarket intake is to increase the amount of air flow the engine receives.

HP gain is 0-15HP. These HP figures are a range as different intakes have different dyno results.

What is an aftermarket intake? Aftermarket intakes can be broken down into two types:
1. Short ram: AKA shorty or ram pod.
2. Cold air intake: AKA CAI.

What does the stock intake look like? To gain a perspective on how aftermarket intakes function, the stock intake features will be shown and discussed for further clarity.

This is the stock intake as viewed from the driver’s side.
The “U” shaped assembly and the tank that connects to it on the left is commonly referred to as the snorkel,  silencer, or resonator. It is actually hidden in the fender.

Stock Subaru turbo intake piping.
Stock Subaru turbo intake piping.

This is the stock intake as viewed from the passenger’s side.

This is the stock intake as viewed from the passenger's side.
This is the stock intake as viewed from the passenger’s side.

This is the stock intake as viewed from above.
1. Stock “ram intake” funnel.
2. Stock air filter box.
3. MAF sensor.
4. MAF sensor piping.

This is the stock intake as viewed from above. 1. Stock "ram intake" funnel. 2. Stock air filter box. 3. MAF sensor. 4. MAF sensor piping.
This is the stock intake as viewed from above.
1. Stock “ram intake” funnel.
2. Stock air filter box.
3. MAF sensor.
4. MAF sensor piping.
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