R&D Beginnings - WRX Race Intake, Part 1

R&D Beginnings - WRX Race Intake, Part 1

Team Mishi likes to look out for our Subaru community. If you have been following our engineering blog, then you'll notice that we have been rolling out a slew of high quality 2015+ parts WRX. One of the biggest products we launched was our bolt-on intake system. Not only did we provide easy power gains, but our system greatly improved sound, and created a large group of very pleased customers. The gains we produced were a result of reduced restrictions compared to the factory system. A great product that supports stock and mildly modified examples. We are now turning our attention to an even less restrictive iteration that will be designed to support vehicles necessitating maximum airflow.

Our race-inspired design for this WRX intake will take the more aggressive route of obtaining the maximum power potential an intake can deliver to this FA series motor. Keep in mind, this secondary "Race" design will require tuning for safe operation.

It is important to understand that this will be a very different system than our Performance Intake with two very different vehicles in mind. Our Performance Intake is designed for vehicles either on the stock tune, or on the path of basic modifications such as exhaust, tune, intercooler, etc. For those seeking greater power through more extreme modification (turbo upgrade, TGV removal, aggressive tune, E85, etc.), our new Race Intake might be a better option.


With the design of our Performance Intake still fresh in the minds of our engineers, we decided to set some performance objectives so we could keep ourselves on track and focused to achieve the goal for this product: more power!

With that in mind, our basic goals for this version WRX intake are noted below:

- Direct-fit install requiring no vehicle modification
- Unrestricted intake path for maximum power potential
- Perform rigorous testing to ensure performance is repeatable

A more in-depth breakdown is provided below.

Direct Fit
We want to be sure that installing this our Race Intake is as quick and painless as with our previous WRX Intake. Instead of coming up with another new airbox design, our hope is to reuse the airbox from our Performance Intake, which uses the stock air-inlet duct to get the freshest air possible to the filter.

Speed and Power!
To get the most power out of this WRX intake, things needed to be bigger. Enlarging the induction pipe diameter is going to be our first task. Through flow analysis we determined that 3" piping will provide ample flow/volume to adequately support

In addition, we are using a very large air filter to accommodate the increased airflow potential of the larger tubing. With the bigger filter and piping, this setup will not be safe on a stock tune. Those who opt for this system will require an upgraded tune for the car to run correctly, but make no mistake, you will not be disappointed.

WRX Parts Testing
As previously mentioned, we will be putting this WRX intake through some extensive testing to ensure the design meets our requirements in terms of output and flow. Our Dynojet™ will come in handy with this particular portion of development. With the bigger piping, it's important that we note exactly how the intake will increase performance and affect induction. We will look for notable power gains on the dyno graph and a safe AFR output throughout.

Development Beginnings

After placing our airbox into position and hoisting the WRX onto the lift, we began planning out our intake pipe route and design. After some light fabrication and several mockups, we had a rough prototype complete.

Mishimoto's WRX Race Intake

Mishimoto's WRX Race Intake

This piece features a full 3" diameter from the turbo compressor connection all the way to the filter.

You will notice we've topped the pipe with a very large air filter, which should aid in supplying the FA20 with the air it begs for. The total surface area of our Performance Intake features a total of 422 square inches, while our Race Intake has a total of 498 square inches. This equates to about an 18% increase in filter surface area.


With our basic design in place, we needed to create a 3D model that accurately depicts our design. This includes all of ancillary features such as MAF housing placement, the mounting bracket location, and the specific geometry of the pipe.

To capture dimensions from our prototype, we placed the component on our CMM table and started logging each point.

2015 WRX intake up for measurements

CMM modeling of our 2015 WRX intake

Once we have a modeled design, we can begin our fabrication to construct a functional prototype for testing!

A CMM prototype rendering of our 2015 Subaru WRX intake

With the CMM work complete, the model was quickly wrapped up, resulting in the image you see below.

Coming Up!

Dyno testing is on the horizon! Check back next time for a look at some dyno pulls and our results!
Thanks for reading,