2015 - 2021 Subaru WRX STI
Mishimoto recommends that this intercooler kit is not used with the stock ECU programming. It is highly recommended that the customer is able to retune the vehicle’s ECU after installing the intercooler kit. Power gains will vary depending on the size of the turbo, exhaust system, fuel system, and type of ECU tune that is applied to the vehicle.This kit is rated for approximately 600 whp, or 30 psi of turbo boost. Exceeding these horsepower or pressure limits may require a custom-sized front-mount intercooler.
THIS FRONT-MOUNT INTERCOOLER KIT WILL NOT FIT WITH THE MISHIMOTO 2015+ STI OIL COOLER KIT
Here at Mishimoto, we've decided to expand our line of 2015–2019 Subaru WRX STI products. Designed for applications that demand the greatest airflow and cooling capabilities, the Mishimoto 2015–2019 Subaru WRX STI Front-Mount Intercooler will provide your 2015–2019 Subaru WRX STI with the ability to make the most horsepower and torque possible.
This 2015–2019 Subaru WRX STI intercooler kit was designed with the same 28" intercooler as our 2015–2019 Subaru WRX STI front-mount intercooler kit. The massive 3.5" thick core will support up to 600 whp or 30 psi of boost pressure! Smooth cast end tanks make for uninterrupted airflow through the cooler. This results in an intercooler that provides the best airflow and cooling capabilities without excessive pressure drops. Your fully built rally car will have no problem keeping a dense, cold, intake charge with this highly engineered 2015–2019 Subaru WRX STI intercooler kit.
The Mishimoto 2015–2019 Subaru STI Front Mount Intercooler is available in black, silver, and gold to add some style to your upgraded intercooler. This intercooler is also covered by the Mishimoto Lifetime Warranty for a worry-free installation that keeps you going.
- Direct fit for the 2015-2019 Subaru WRX STI
- 3.5" thick intercooler design optimized for maximum flow and rated to 600 whp
- No modification to front bumper and retains stock fog lights
- Includes black powder-coated steel crash bar
- Available in silver, black, or gold
- Mishimoto Lifetime Warranty
|FITS||2015–2021 Subaru WRX/STI
|INSTALLATION TORQUE SPECS||27 in-lbs (3N*M) recommended for all t-bolt and constant tension t-bolt clamps. These clamps have an operating range of 18-35 in-lbs (2-4N*M). Do not exceed the maximum torque rating of 35 in-lbs (4N*M).
22 in-lbs (2.5N*M) recommended for all worm-gear clamps. These clamps have an operating range of 18-27 in-lbs 2-3N*M. Do not exceed the maximum torque rating of 27 in-lbs (3N*M).
|SILICONE COUPLERS||(1) Turbo to Hot Pipe Coupler (for stock turbo)
(1) Turbo to Hot Pipe Coupler (for aftermarket turbo)
(1) 2.25" – 2.5" Silicone Transition Hose
(1) 2.5" – 2.75" Transition Coupler
(1) 2.75" Straight Coupler
|PIPE DIAMETER||2.5" – 2.75" Intercooler to Pipe Hoses
|CONSTANT TENSION T-BOLT CLAMPS SPECS||(2) 1.5" T-Bolt Clamps
(1) 2.00" T-Bolt Clamp
(2) 2.5" T-Bolt Clamps
(4) 2.75" T-Bolt Clamps
(5) 3" T-Bolt Clamps
|HOT-SIDE INTERCOOLER PIPE SPECS||Made from polished mandrel-bent aluminum
|CRASH BAR SPECS||– Tubular Steel construction with black powdercoat
– Application-specific mounting holes
– 6.5 lbs
|INTERCOOLER/THROTTLE BODY COUPLER SPECS||– 3.25" length
– 2.75" I.D.
– 3.00" O.D.
– 4mm thick
|STI BPV HOSE SPECS||– Application-Specific Bend for this Kit
– 1.25" I.D.
– 1.50" O.D.
– 4mm thick
|TANK WALL THICKNESS||3.5 mm
|MAX REC. PSI||30 psi|
|CORE SIZE||28" x 8.05" x 3.5"
|MAX REC HP||600|
(1) Performance Intercooler
(1) Steel Crash Bar
Mishimoto Lifetime Warranty
COOL YOUR CHARGE! THE 2015 WRX FRONT-MOUNT INTERCOOLER BUILD, PART 3: PIPE ROUTING AND FABRICATION
Crash Beam Fabrication
After an unsuccessful test fit of our existing bumper beam on the 15’, we started from scratch to create a beam specific for the 15’ chassis. First we hacked off the end tanks of our cooler so we were left with a bare core. This would provide some freedom to design our crash beam and later work on the end tank direction. Next we cut out some new mounting plates and fit them into position.
Next we fabricated a beam for mounting the cooler. The beam would run parallel across the front of the vehicle and attach to each mounting plate.
We then added the connector legs to attach this beam to the mounting plates. After a few tweaks, this guy was in position and ready to rock!
Intercooler End Tank Fabrication
Now that our crash beam was in place, we turned our attention to the end tank design for this kit. As noted earlier, the existing end tanks for this cooler were far too long; we would need shorter tanks to allow space for pipe routing on the 15’.
We started by modeling these tanks in a foam material. This material is easier to modify compared to aluminum, and we can mold it to our preferred shape and size.
Next, we pulled out the TIG and got to work replicating these tanks in aluminum, as we needed to test this kit once complete.
First, the component was printed in a flat-pack drawing, which indicates the cutout and bends needed to create this tank from a flat sheet of aluminum.
This piece was then cut out and bent to position!
We then handed the torch to Dan (literally) and set him to work welding the end tank. A pipe end was also welded to complete the construction. Here is the finished tank next to our original foam prototype.
And finally we fully welded this tank to our core.
Keep in mind this is strictly a prototype for functionality and test fitting. Our final intercooler design will feature the same core combined with cast end tanks in this same shape. Cast tanks provide a more robust construction with far less failure points compared to a sheet metal end tank. Additionally, by casting this component we can create an extremely smooth internal surface that will provide the best possible airflow through the core.
This core is already proven, so as long as our dyno testing gives us positive results, we will be sticking with this very efficient bar-and-plate core. Take a closer look!
COOL YOUR CHARGE! THE 2015 WRX FRONT-MOUNT INTERCOOLER BUILD, PART 4: DYNO TESTING
Time for the fun part of development, product testing! Since this is an intercooler, we would certainly need to put the WRX on the dyno for some pulls and data collection. It would be interesting to see how the installation of a front-mount system has an impact on turbo spool, intake temperatures, and perhaps even power output.
The first step toward data collection is to prepare our sensor bungs and install our pressure and temperature sensors. We installed our bungs within the inlet and outlet intercooler couplers.
Once complete we strapped the WRX to the dyno and started making our pulls! Check out the images and video from our tests!
After making several pulls we compiled our results into a series of charts that should help you make an informed decision regarding your intercooler needs. Do you need a front-mount? Is the stock top-mount going to be sufficient for your needs? These great quandaries of the mind are answered below.
First, a look at outlet temperatures of the stock intercooler setup compared with our front-mount system.
At the start of the pull, the front-mount already shows improvements, displaying a 20°F temperature drop compared to the stock intercooler. As the pull progresses, the top-mount outlet temperatures begin to rise at around 4,300 rpm and eventually peak at around 120°F . The front-mount setup starts at around 70°F and peaks at right around 82°F toward the end of the pull. This reflects a nearly 40°F difference in intake temperatures! Also, keep in mind that our ambient temperature in the shop is right around 65°F, so our front-mount system is keeping temperatures to within 17°F of ambient – pretty impressive! In a nearly identical test with our new 2015 WRX top-mount, we saw peak temperatures around 90°F.
Our next chart shows outlet temperature relative to boost pressure.
This chart shows outlet temperatures during spool. The entire length of this plot data was collected in the short amount of time it takes to increase from 4 psi to peak pressure. As you can see, both plots stay relatively level during this time. Only during sustained high boost does the temperatures begin to rise, and we see a bigger difference between the two intercoolers. That said, we are still seeing about a 20°F drop between the two cooler setups during initial turbo spool.
The next chart is the one folks have been waiting for. Front-mount intercooler setups typically produce greater lag, which is why one might stray from this particular setup on a lower-powered build. To demonstrate this we produced the chart below, which shows PSI/RPM for the stock intercooler system and the Mishimoto front-mount.
We started our pulls at around 3,000 rpm, which showed around 6 psi of pressure for both setups. Through 18 psi we were able to achieve nearly identical pressure per rpm. You will also notice the front-mount peaks at a slightly higher pressure, which is likely due to the lower intake temperatures. Either way, lag with the front-mount was extremely minimal.
After fitting the bumper once again, we decided clearances were a bit tighter than we wanted on the cold side. Instead of having this pipe potentially rub the back of the bumper, we decided to modify the route a bit to provide improved fitment. Both the upper and lower portions of this pipe were modified.
In addition to the new route, we intend to manufacture a portion of this piping out of wire-reinforced silicone. This portion will be passing between the headlamp and the washer reservoir. By using silicone we can ensure that the component will not be damaged from rubbing and will not vibrate or cause noise concerns within the cabin.
Catch Can Use
We do our best to make each of our components compatible with each other, and we were able to do so with a majority of our products, excluding our direct-fit catch can kit. Unfortunately the cold-side piping interfered with our driver’s side catch can mounting bracket. With a bit more space in the rear of the engine compartment, we were able to relocate this unit with a new bracket and revised lines. Check it out!