Stay Frosty – Performance Front-Mount Intercooler Kit for the 2022+ Subaru WRX

Stay Frosty – Performance Front-Mount Intercooler Kit for the 2022+ Subaru WRX

One of the most common modifications for WRX owners, particularly those who plan to tune for performance, is upgrading to a performance intercooler. Here at Mishimoto, we’ve been making performance intercoolers for the WRX for quite a while. Since we’ve covered the last few generations and already made a top-mount intercooler for the current fifth generation, we figured the next logical step was to produce a front-mounted version for the 2022+ WRX.

 

Let’s take a look at what our engineers had in mind when they got to the drawing board.

 

Design Overview

  • Create an intercooler that performs better than the stock intercooler
  • Minimize the pressure drop normally associated with a front-mount intercooler kit
  • Include replacement bumper bar with a location for the factory tow hook
  • Direct fit kit with minimal trimming required
  • Allow for fitment of aftermarket front strut bars

 

Stock Evaluation

The first step to designing a performance product that aims to outperform its stock counterpart is simple—take a long, hard look at the stock version.

 

The stock intercooler of the fifth-generation WRX is top-mounted and fed cool air through the hood scoop and ducting. The benefit of top-mounted intercooler systems is that there’s a short path from the turbo to the throttle body, which minimizes pressure drop and gives a quick response when the driver puts the pedal down. The downsides to this style of intercooler are the risk of heat soak and comparatively less airflow. This is because it’s mounted on top of the engine, which also means the core size must be smaller because of limited space.

 

Situated behind the grille and in front of the radiator, we knew our front-mount design wouldn’t face those same challenges. Heat soak is much less of a concern since it’s much further from the engine, limited airflow is no longer an issue as the front of the vehicle gets plenty, and the front of the vehicle offers much more room than on top of the engine. However, front-mount intercoolers have a much greater volume and distance for air to travel, meaning there’s more opportunity for pressure drop. Our engineers had to keep this in mind throughout the design process.

 

Design Process

Our engineers started by scanning the WRX with Mishimoto’s Faro 3D laser scanner. Using this data, we determined the most efficient way to route the piping and determine what size core would fit behind the bumper without needing to trim it. This also allowed us to design our replacement bumper bar with a precise location for the tow hook receiver. We then tested two different core configurations with varying internal fin specifications so we could achieve a balance between cooling capacity and pressure drop.

Figure 1 Intercooler inlet and outlet have a matched internal diameter to promote smooth flow.

 

To further minimize pressure drop, we matched the inlet and outlet sizes to the 2.5” inner diameter of the charge pipes, which gave our intercooler uninterrupted flow. This same idea was used at the throttle body adapter, and the 2.5” sizing was used as much as possible throughout the design.

 

One place we didn’t use this sizing was the turbo outlet. Measuring at only 41mm, a jump to the 60mm inner diameter of the 2.5” pipe would’ve restricted flow. To solve this, we used a CNC-machined turbo outlet adapter that gradually transitioned from the 41mm adapter to the 54mm internal diameter of the turbo outlet pipe and then transitioned to 60mm at the first pipe transition. With this adapter, a much smoother flow was achieved.

 

The final core size for our intercooler was 675mm x 308.5mm x 100mm, which boasts approximately a 318% increase in size over stock and a 159% increase in frontal area. To accommodate this larger core, the factory bumper bar had to be removed. In its replacement is our fabricated bumper bar, which maintains the WRX’s structural rigidity and protection in the event of a crash, as well as maintaining the factory location for a tow hook. We also ensured that the inlet and outlet piping was precisely routed to go around the side-front impact bars.

Due to the new front-mounted location, our engineers encountered an issue with the ambient air temperature sensor. This sensor was now located behind the intercooler core, which led to readings much higher than the actual ambient temperature. To solve this, our core includes a bracket that allows the sensor to sit above the core where it could access fresh air and provide accurate measurements.

 

Testing

Next came the fun part—testing.

 

For our testing we used a 2022 Subaru WRX with a 6-speed manual transmission, equipped with a Mishimoto Thermostatic Oil Cooler Kit, a Mishimoto Air Intake System, and a Mishimoto Radiator with Mishimoto hoses. To conduct consistent ramp tests, we used our Dynapack™ dynamometer.

To collect data useful for comparison, we tested the stock Subaru intercooler, our existing top-mounted intercooler, and our new front-mounted intercooler. Pre-intercooler sensors were placed in the turbo outlet charge pipe and post-intercooler sensors were placed right before the throttle body. This setup allowed us to simultaneously collect data for pressure drop and air temperature fluctuation across the three different intercoolers.

 

With an ambient air temperature that ranged from 73-80°F, we idled the WRX until it warmed up to 190°F, and we kept it running in between runs to maintain a consistent coolant temperature. Our engineers conducted dyno runs until multiple consistent runs were recorded. As a final test, six back-to-back dyno runs were done on each intercooler to simulate heat-soak conditions.

 

Temperature

IntercoolerAmbient Air to Peak Outlet Temperature Difference
Stock10°F
Mishimoto Top-Mount7°F
Mishimoto Front-Mount6°F

 

Success! Our new front-mount intercooler cooled the charge air better than our top-mount and significantly better than the stock intercooler on a single pool. At 6000rpm engine speed, our intercooler efficiency was 97%. Not only did our front-mounted intercooler outperform stock, it provided consistent outlet temperatures across all 6 pulls despite the inlet temperature consistently rising, while the stock intercooler comparatively did not.

 

Pressure

IntercoolerPeak Pressure DropAverage Pressure Drop
Stock1.5 psi0.9 psi
Mishimoto Top-Mount1.1 psi0.6 psi
Mishimoto Front-Mount1.5 psi1 psi

 

Once again, we were pleased with these results. When considering the extra volume and distance the air has to travel in a front-mount intercooler, there was almost no increase in pressure drop compared to the stock top-mount system. We had achieved our goal of minimizing the pressure drop typical of front-mount intercoolers.

 

Power

With a peak increase of 8.3 horsepower and max gains of 12 horsepower and 11.8 foot-pounds of torque, we found our power gains to be a notable increase over stock.

Conclusion

The Mishimoto Performance Front-Mount Intercooler Kit for the 2022+ Subaru WRX is an ideal choice for WRX owners seeking the next step in performance. Testing revealed significant improvements over stock, boasting gains that are beneficial on the track, dragstrip, and road. Not only is it safe to run on a stock tune, our intercooler’s ability to prevent heat soak means it won’t pull timing, offering consistent power performance and preventing engine damage. Our kit contains everything needed for a simple and straightforward installation with no cutting of the body or bumper, no bending of the A/C lines, and fits with existing strut bars.

 

Thanks to our engineers’ determination to minimize pressure drop, you can enjoy the cooling efficiency of a front-mount intercooler without sacrificing the responsiveness that a top-mount intercooler offers. Designed for dependable performance and backed by Mishimoto’s Lifetime Warranty, get the most out of your fifth-generation WRX by upgrading today.