2015 STI parts fabrication

A Front-Mount for the 2015 STI, Part 2: Cold-Side Intercooler Pipe Fabrication

Our first segment of this STI intercooler project involved the test fitting of our WRX crash beam and intercooler core. We were able to verify fitment of both pieces, which allowed our team to move on to piping fabrication. We are starting this kit with the cold-side pipe, which we’ve decided to place this on the passenger side of the engine bay to reduce the piping length as much as possible. Following this strategy should help reduce lag seen by the driver.

Pipe Fabrication

The cold-side pipe is a great place to start because we are able to use a portion of one of our existing kits. Because the 2015 model shares the EJ from the 2008+, we will be reusing the pipe that attaches to the throttle body and incorporates the BPV (bypass valve).

2015 STI front-mount intercooler development
2015 STI front-mount intercooler development

This pipe provides optimal clearance through its path within the engine bay. It routes from the throttle body into the portion of the engine bay that previously contained the intake airbox.

2015 STI front-mount intercooler development
2015 STI front-mount intercooler development

Our team would be working from the end of this pipe to complete the airflow route to the intercooler.

Throttle body pipe route for STI intercooler development
Throttle body pipe route for STI intercooler development

We then started piecing together our pipe route. This involves careful measurement followed by cutting, fitting, and grinding until the route and fitment are perfect.

2015 STI parts fabrication
2015 STI parts fabrication

After some trial and error, along with test fitting with the bumper in place, we had a completed mock-up pipe.

2015 STI parts fabrication
2015 STI parts fabrication

We then tack-welded each joint on our prototype for additional rigidity.

2015 STI parts fabrication
2015 STI parts fabrication

One final test fit was performed to ensure the accuracy of this prototype.

2015 STI front mount intercooler piping fabrication
2015 STI front mount intercooler piping fabrication

At this point we can remove the prototype and collect all the needed dimensional data needed to create a 3D model of our pipe. This will help ensure that our final product corresponds exactly to the design, making for perfect fitment of our STI intercooler kit.

Intake Pipe

You probably noticed in a few of the posted images that an intake pipe and filter are installed. Because of the pipe routing from the engine bay to the front bumper, the stock airbox cannot be reinstalled with this kit.

Intake pipe for STI intercooler kit
Intake pipe for STI intercooler kit

As with the pipe attached to the throttle body, we will be stealing this intake setup from our existing 2008–2014 kit. This setup has proven effective and will work well for our 2015 STI front-mount intercooler kit. We will need to modify only the mounting bracket to function with the different engine bay layout on the 2015. Easy!

Coming Up: Hot-Side Pipe Fabrication

Check back soon for a look at the fabrication process for our hot-side pipe!

Keep an eye on our blog for additional development of 2015 STI parts.

Thanks for reading!

-John

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