Mishimoto 2015 Subaru WRX CVT Transmission Fluid Cooler, Part 1: Project Introduction and Goals

Mishimoto 2015 Subaru WRX CVT Transmission Fluid Cooler, Part 1: Project Introduction and Goals

Interested in purchasing our WRX transmission cooler? Check out our product page for more information!

Mishimoto Subaru WRX CVT Transmission Cooler

Mishimoto CVT test vehicle

An automatic Subaru WRX … what has this world come to? We’ve read your comments on the forums and social media regarding our purchase of a CVT-equipped 2015 WRX for new product development. Why would anyone want this vehicle? Who would purchase it, and for what reason? Is this even an enthusiast’s vehicle anymore? All great questions. We’ve responded to these comments that we are developing products for both the 6-speed and CVT models. Our primary target/reasoning for the CVT purchase is to develop a transmission cooler, but the majority of our staff had a similar attitude as our followers: It just didn’t seem right. After spending some time with the vehicle and behind the wheel, however, most of our production team members are sold on the CVT. Of the ten vehicles I have owned, only one was an automatic, and it was sold for that specific reason. As I age gracefully, I have found an appreciation for automatics, especially for multiple drivers and multiple uses. Modern automatics are quite different compared to those from five or ten years ago. They are no longer considered as downgraded, less enjoyable vehicles, but more as an alternative. For those who are still skeptical, go to your local Subaru dealership and request a test drive; I bet you will be impressed.

I think these cars will become serious competitors in autocross in the coming years, especially since we recently uncovered the incredible power gains possible with a few minor bolt-on modifications. Anyway, let’s return to the project.

CVT transmissions do not utilize the internal components that previous standard autotragics used. Despite this, CVT transmissions still require fluid temperature regulation just like any other transmission. Fluid temperature is vital for component longevity and reliability.

We needed a way to regulate the temperature and assist the stock system. Subaru utilizes a liquid-to-liquid cooler for heat transfer. Engine coolant and transmission fluid flow through a cooler, working together to regulate fluids. These liquid-to-liquid coolers are generally quite efficient. This particular system has been designed for the stock 210 whp (or so) and does a decent job at keeping temperatures at bay under normal conditions. So what happens when you add around 100 whp? Engine and underhood temperatures are sure to rise in normal driving conditions as well as with track/aggressive driving. Reaching 300 whp is an exhaust, intake, and tune away, which are commonly the first modifications for the basic enthusiast. Check out this image of the stock cooler!

WRX stock liquid-to-liquid CVT cooler WRX stock liquid-to-liquid CVT cooler

The lines are  rubber with a sheathing to protect them from any rubbing. This unit mounts to the side of the engine block on the passenger side. After evaluating the stock unit, our team decided to design a product to assist the stock unit. The stock setup also functions as a fluid warmer, which will help bring the fluid up to operating temperature, and then our supplemental cooler will help retain optimal temperatures. Check out our test vehicle below!

Mishimoto CVT test vehicle Mishimoto CVT test vehicle

So we had everything we needed to start the project: a team of engineers, an office full of car enthusiasts, a 2015 WRX, testing equipment, and a shop full of fabrication equipment. First, we set a few simple goals to follow to obtain the results we wanted.

Project Goals

  1. Kit must be easy to install and require no vehicle modification.
  2. Cooling performance gains must be proven through real-world testing.
  3. Cooler must supplement the stock liquid-to-liquid cooler.

With these simple goals in mind, our engineering team began to envision and create the best-performing product possible A quick breakdown of these goals is detailed below.

Easy Install

We pride ourselves in developing products that are easy to install and bolt on to your stock vehicle. Our goal is to provide efficient, accurate instructions for our products, which can be installed with common hand tools. The WRX is a brand new vehicle. I am not sure that many folks would want to hack into their new vehicles. This kit will feature a completely reversible installation so if you choose to remove it, there will be no signs that it was installed. We too are consumers of the performance aftermarket world, and we can appreciate a product that installs perfectly and looks like stock equipment.

Cool It

The primary focus for this project is cooling performance. We want to reduce temperatures as efficiently as possible so you can drive your car in any way you choose, whether tackling those back roads you have been eying, or that weekend autocross. Our goal is to provide efficient cooling so you can truly enjoy your new WRX!

A Helping Hand

As mentioned before, our cooler would not replace the stock cooler; instead it would be supplementing the stock unit. This system is also rather efficient for engine oil cooling, as we found when testing our 2015 WRX oil cooler kit.

That’s all for our first installment of the build. Check back next time for the development of our first prototype design!


Interested in purchasing our WRX transmission cooler? Check out our product page for more information!

Mishimoto Subaru WRX CVT Transmission Cooler