Tag Archives: Engine

Banjo Bolt (Union) removal/install on a Subaru WRX STi

Banjo Bolt (Union) removal and install on a Subaru WRX STi:

This is Banjo Bolt step by step guide on the removal and installation of a Banjo bolt and new copper washers for a Subaru WRX/STi or any other turbocharged Subaru.The Banjo bolt is the one with a filter screen that others have indicated should be cleaned or replaced periodically. Subaru calls it a “Union screw (with protrusion).”
Tools needed:
12 mm socket – for intercooler bracket bolt
14 mm deep-well socket – for up-pipe bracket nut and bolt
10 mm socket or wrench – for stock turbo heat shield bolt
17 mm ratcheting wrench – for Banjo bolt
10 inch or longer extension – to reach up-pipe bracket bolts

Parts needed:
Union screw/Banjo Bolt (If replacing which I highly suggest you do.) – Subaru part # 14445AA090

Subaru 14445AA090 Oil Filter Bolt


Genuine Subaru Turbo Banjo Bolt with Screen – 14445AA090a
Copper washers (2) – Subaru part # 803912040
Subaru 803912040 Banjo Washer


Removal and re-install takes about one hour.

Start by removing any heat shields that are in the way. I have the SPT heat shield that comes off by removing the 12 mm intercooler support bolt.
(See pic “Engine bay area”). I also have the stock turbo heat shield installed. I didn’t take it off, but there will be a little more room to work if you do. A 10 mm socket is needed to remove the stock heat shield bolts.

The next page will describe the removal and re-installation process of the Banjo Bolt and copper washers.

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.