Category Archives: Intercooler

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.
Pages: 1 2 3
EJ257, Intercooler, JDM, STi, Subaru, TMIC, Turbo, WRX

TMIC basics on a Subaru WRX/STi

TMIC basics on a Subaru WRX/STi:

The primary purpose of a top mount intercooler is to reduce post turbo air temperature prior to entering the combustion chamber via the throttle body.

HP gain is around 15HP. This figure can vary as many TMICs replace the restrictive OEM piping and 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.

How much HP can my stock TMIC hold? 300WHP on the WRX and 400WHP on the STi are attainable. That does not mean those power levels are 100% efficient, but that those power levels are attainable with their OEM TMICs. As discussed below though, TMICs are not meant to be HP rated, but rather CFM related, but this is an FAQ so the HP figures are given as a good “bad” answer.

TMIC basics on a Subaru WRX/STi: 04-07 STi oem TMIC
TMIC basics on a Subaru WRX/STi: 04-07 STi OEM TMIC

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

I have a 2008/2009 model, any differences? Yes. Your engine bay has an entirely new layout vs. the 2002-2007 models.

TMIC basics on a Subaru WRX/STi: A 2008 STi stock TMIC
TMIC basics on a Subaru WRX/STi: A 2008 STi stock TMIC
Pages: 1 2 3 4 5
exhaust, Impreza, Intercooler, STi, TMIC, Turbo, WRX

Subaru WRX and STi Exhaust general info

Subaru WRX and STi Exhaust general info:

The primary purpose of an aftermarket exhaust is to remove or replace the stock catalytic converter(s) with a better flowing unit. It also increases the exhaust diameter for better flow. The term “aftermarket exhaust” can be broken down into the three main types:

1. Turbo back exhaust (TBE) covers items 1-4 as described below.
2. Cat back exhaust (CBE) covers items 3&4 as described below.
3. Axle back exhaust (ABE) covers item 4 as described below.

The stock WRX Subaru exhaust consists of:

1. Downpipe (with cat) | 2. Midpipe (with cat) | 3. Rear Exhaust Pipe | 4. Axle Back Muffler

The stock WRX Subaru exhaust consists of: 1. Downpipe (with cat) | 2. Midpipe (with cat) | 3. Rear Exhaust Pipe | 4. Axle Back Muffler
The stock WRX Subaru exhaust consists of: 1. Downpipe (with cat) | 2. Midpipe (with cat) | 3. Rear Exhaust Pipe | 4. Axle Back Muffler

Keep in mind that the above information is catered to the 2002-2005 WRX and is likewise applicable to all years of the STi, though there are slight variations. For example, the STi (all years) has a catless uppipe and the 2006+ WRX has a one piece downpipe/midpipe.

HP gain is dependent on the type of exhaust chosen. TBE gains are 20-30HP. CBE gains are 5-15HP. ABE gains are 5-10HP. These figures are highly debated as different manufacturers use different dynos with different cars with different levels of mods. It also varies because exhausts use different amounts of catalytic converters or are catless.

What about overall fitment between the WRX and STi or different model years? All OEM or aftermarket exhausts designed for 02-07 WRX/STi will fit either the 02+ WRX sedan/wagon or 04+ STi. Occasionally, you will have a slight fitment issue with some models (moreso if your car has the optional rear differential cover) that usually get be fixed via hanger adjustment, longer exhaust hangers etc. 06+ models have fitment issues with some exhausts (mainly the muffler portion) due to the new rear diffuser.

I have an 06+ WRX, is the downpipe the same? No. The 2006+ WRX has a unique exhaust in that it’s downpipe is both the downpipe and midpipe sections of the “older” exhaust. This means you must use a “long” downpipe to bolt up to the rest of your exhaust system. A full TBE will fit fine, but when replacing just the downpipe, you must use a long downpipe. Check with your Vendor for other possible fitment issues prior to ordering.

Pages: 1 2 3 4 5 6
EJ257, Impreza, Intercooler, STi, Subaru, Turbo, WRX

VF39 STi turbocharger onto your WRX/Forester

VF39 STi turbocharger onto your WRX/Forester:

Swapping a STi VF39 turbocharger onto your WRX/XT is really easy. Find out here the step by step process on swapping a VF39 onto your Subaru WRX/XT.

You can buy a brand new VF39 Turbocharger here:

Subaru 14411aa5729L Turbocharger

A lot of people seem to be getting hung up on the oil return lines and coolant lines. The coolant lines and banjo bolts from the TD04 ARE interchangeable if your vf39 doesn’t have them (mine didn’t). The oil return line is not and must be modified in order to fit the vf39, (mine had it). Or get a new one from the dealer. I will explain in the pictures when I get to these items.

First remove the intercooler, pretty self explanatory there are 2 bolts that it mounts to, 2 on the BPV and the hoses. Done Deal. Next the heat shield. You should be somewhere around here:

VF39 STi turbocharger onto your WRX/Forester: Start removing the head shield and downpipe.
VF39 STi turbocharger onto your WRX/Forester: Start removing the head shield and downpipe.

 

Remove the downpipe:

VF39 STi turbocharger onto your WRX/Forester: Start removing the downpipe.
VF39 STi turbocharger onto your WRX/Forester: Start removing the downpipe.

Then remove the bolt for the oil inlet (top of the turbo), and start removing the coolant lines (2 lines coming off the side of the turbo 1 goes up 1 goes down). Be careful as you will lose coolant during this step be prepared to either catch it under the car or plug the line:

VF39 STi turbocharger onto your WRX/Forester: Remove coolant lines and oil lines.
VF39 STi turbocharger onto your WRX/Forester: Remove coolant lines and oil lines.

Then remove the 3 bolts that hold the turbo to the uppipe. Loosen from the intake remove vacuum lines and anything else attached to the turbo and you should be ready to take it off. The hose that the oil return line fits into is directly under the turbo and you should probably just lift straight out. Try to leave the hose where it is and lift the line out.

Now that the turbo is off you can start swapping out the parts you need from the td04. The coolant lines from the TD04 will fit the VF39 however they are attached and too close together to fit directly on the VF39 see pic:

VF39 STi turbocharger onto your WRX/Forester: changing out oil lines.
VF39 STi turbocharger onto your WRX/Forester: changing out oil lines.
Pages: 1 2