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Old 08-22-2014, 02:28 PM   #1
Mishimoto
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Member#: 207954
Join Date: Apr 2009
Default Mishimoto 2015 WRX Aluminum Radiator Build Thread

Hey guys,

We have been working towards finalizing our aluminum radiator design for the 2015 Subaru WRX. Check out our build-thread either on our engineering blog or posted below!

Engineering Blog: Mishimoto 2015 Subaru WRX Performance Aluminum Radiator Product Development

Mishimoto 2015 Subaru WRX Performance Aluminum Radiator, Part 1: Product Introduction and Stock Radiator Overview

The new 2015 WRX is a great toy for both daily use and as a weekend track warrior. The introduction of the FA20DIT into the WRX chassis has been well received, and from the reviews thus far, Subaru has done a great job with the new model. Although some might disagree with the styling, overall the car handles and performs very well. As for value, the 2015 model is a pretty decent bang for your buck. For those looking to track their brand new vehicle, a few bolt-on modifications will raise power levels significantly. A simple intake and tune will raise power to 275+ whp, which is a huge increase over the 210 whp we saw from a completely stock vehicle. Reaching 300 whp is potentially obtainable with a few additional exhaust modifications. We are currently in the process of testing our prototype J-pipe to confirm this!

With improved power comes the need to monitor and regulate fluid temperatures. Oil and coolant are the lifeline of your engine. Keeping these fluids properly regulated will extend the life of your FA and make your track days more enjoyable. Mishimoto already took care of oil issues with our direct-fit oil cooler kit for the 2015 WRX, which lowered temperatures by 25+°F. This is a huge drop in temperatures and will also make an impact on coolant temperatures for your Rex. For CVT users we developed a direct-fit CVT cooler that dropped temperatures by +15°F. The next component we want to bulletproof is the radiator; this is our most well-known product segment. Our GD and GR WRX/STi radiators are well received in the enthusiast world and are a fantastic replacement for the failure-prone stock unit.

Before diving into product design, we removed the stock unit to evaluate any changes made from the previous WRX generation. Take a look at the stock radiator after we removed it!


Stock 2015 WRX radiator removed

Once removed from the vehicle, we disconnected the hoses and the fans and inspected the radiator.


Stock 2015 WRX radiator removed


Stock 2015 WRX radiator removed

Although some features and dimensions differ, this radiator is similar to the previous generation. It features a fill neck and cap, fan shroud mounts, and similar inlet/outlet locations.

The key portion of this component that relates to performance is the core itself. Radiators on vehicles released in the past few years have been equipped with very thin yet extremely dense cores. This allows for greater fin surface area and a greater number of coolant tubes, which results in better heat transfer. Manufacturers can reduce the radiator size to create a more compact engine compartment. Every millimeter helps. Check out a few shots of the stock core!


Stock 2015 WRX radiator core


Stock 2015 WRX radiator core


Stock 2015 WRX radiator core

As you can see, Subaru equipped this vehicle with an extremely dense core. It features a single-row core with straight external fins. Take a quick look at the thickness of the factory core.


Stock 2015 WRX radiator core thickness

The stock radiator is paper thin, measuring only 16 mm in thickness. This is an area where we can certainly improve.

Using the dimensions from the stock unit and our existing GR WRX radiator, we designed a prototype unit for the 2015 model. This first prototype would have a dual-row core with aluminum end tanks. We would be increasing the overall thickness of the radiator and evaluating the fitment once our prototype was complete. Check back next time for the fitting of our initial prototype.

Thanks for reading!
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Old 08-22-2014, 06:43 PM   #2
Redeemed77
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Old 08-25-2014, 10:19 AM   #3
Mishimoto
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Thanks! We have an update coming this afternoon!
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Old 08-25-2014, 02:28 PM   #4
Mishimoto
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Part 2 of this build is up! Check it out.

Mishimoto 2015 Subaru WRX Performance Aluminum Radiator, Part 2: Evaluation of First Prototype Radiator

Now that we had our first prototype unit in, it was time to evaluate fitment and determine if any changes were necessary when compared to the stock unit. First, we swapped the shrouds to see if any fitment issues existed because of the added size of the Mishimoto unit.


Mishimoto prototype 1 (right) fan shroud fitment


Mishimoto prototype 1 (top) fan shroud fitment

Both the stock and Mishimoto plug-n-play aluminum fan shrouds fit perfectly with the mounting points on our prototype radiator. After verifying this fitment, we installed the prototype in the vehicle to ensure that all other fitment points were spec’d correctly.


Mishimoto prototype 1 installed


Mishimoto prototype 1 installed


Mishimoto prototype 1 installed


Mishimoto prototype 1 installed

The prototype unit fit quite nicely! We had some minor adjustments to make with a few end-tank features, but for the most part, mounting points were spot on. The core we designed for this prototype is 42 mm thick, more than two times the thickness of the stock unit. Core fin density in this prototype was similar to the stock unit. After a discussion with our team we determined that the core on our first prototype would need a few modifications. First, we would reduce the thickness of the core. The FA20DIT front-mounted turbocharger setup would likely present some potential fitment concerns. We decided to allow for future turbocharger and charge pipe upgrades by providing some additional clearance for upgraded components in this area. By decreasing the core thickness to 35 mm, our radiator would still be double the thickness of the stock unit and would provide a nice increase in fluid capacity.

A second modification to our prototype core will be in the fin and tube composition. Instead of simply matching the density of the stock unit, we would be improving upon it. Our radiator will utilize shorter fins, which allow for more overall rows and a greater surface area. A greater fin surface area provides more heat-transfer contact points, which then result in lower fluid temperatures. This core would be a two-row design, providing greater fluid capacity.

Once we had a plan for our second prototype, we set to work putting together the models and drawings. Check back next time for the introduction and evaluation of our second prototype unit!

Thanks!
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Old 08-26-2014, 11:25 AM   #5
Mishimoto
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Check out the evaluation of our second prototype unit in part 3 below!

Mishimoto 2015 Subaru WRX Performance Aluminum Radiator, Part 3: Second Prototype Evaluation

No need for an introduction, let’s check out our second prototype!


Mishimoto prototype 2 radiator


Mishimoto prototype 2 radiator


Mishimoto prototype 2 radiator

So what can we tell from these images? The unit as a whole is very precise, and the TIG-welding is straight and accurate. All mounting points and adjustments to the previous version should make this a drop-in fit. One major difference you will notice from the GR radiator is the lack of an overflow port on the passenger top tank. On the previous generation, this line would run to the expansion tank located on the intake manifold. The FA20 does not utilize such a reservoir, so this port is removed.

Let’s take a closer look at the core of this prototype!


Mishimoto prototype 2 radiator core evaluation


Mishimoto prototype 2 radiator core evaluation

The fin height is a touch shorter than the stock core, allowing us to fit more tubes into the radiator itself.

A quick measurement of the prototype core thickness reveals the 35mm core we designed!


Mishimoto prototype 2 radiator core thickness

Here are a couple shots of this prototype next to the stock radiator.


Mishimoto prototype 2 radiator (right) and stock radiator (left)


Mishimoto prototype 2 radiator (bottom) and stock radiator (top)


Mishimoto prototype 2 radiator (bottom) and stock radiator (top)

The Mishimoto prototype unit dwarfs the factory radiator! This increase in size will have a substantial effect on cooling performance, something we plan to test very soon! After verifying that this unit fit perfectly in the vehicle, we set a plan to collect data so we could compare the cooling efficiency with the stock radiator. Check back next time for a full rundown on the testing process and our results!

Thanks
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Old 08-27-2014, 01:02 PM   #6
Mishimoto
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This project is complete! Check out our testing results in part 4 below!

Mishimoto 2015 Subaru WRX Performance Aluminum Radiator, Part 4: Prototype Radiator Performance Testing and Project Completion

Now that we had a finalized prototype, it was time to test this component to ensure that our improvements over the stock unit resulted in real-world advantages for our customers. An aluminum radiator provides the instantaneous benefit of increased reliability over the stock plastic unit. Despite this, cooling performance is always our primary goal with a heat exchanger.

Prior to actual road testing, our engineering team put together a few charts illustrating the improvements over the stock radiator.


Comparison of coolant surface area in Mishimoto and stock radiators

Coolant surface area refers to the space occupied by the tubes in the radiator. The amount of coolant surface area affects both fluid capacity and overall heat transfer contact points. A larger coolant surface area results in greater heat transfer and lower temperature. The Mishimoto prototype features a 42% increase in coolant surface area compared to the stock radiator.


Comparison of air surface area in Mishimoto and stock radiators

The next improvement is seen in air surface area, represented by external fin surface area in the chart above. Airflow passes through the fins to transfer heat from the coolant tubes. Once again, a larger surface area will result in greater heat transfer. The Mishimoto prototype unit increases air surface area by 34% compared to the stock radiator.

With the additional thickness of the Mishimoto radiator and its dual-row core, the fluid capacity is increased significantly. The stock radiator’s fluid capacity is 0.39 gal, while the Mishimoto radiator’s fluid capacity is 0.84 gal. This amounts to a 117% increase in capacity of the Mishimoto radiator over stock.

Now to the road testing! First we installed our temperature sensors on the radiator hoses and prepared our data collection tools.


Mishimoto radiator with temperature sensors installed

Our test vehicle would be the Mishimoto 2015 WRX CVT-equipped shop vehicle. All data points were collected on the highway and compiled on the same day. The vehicle was driven at 60 mph cruising speeds for 5 minutes, for each particular setup. Special attention was given to the traffic in front of the WRX to ensure that a fresh stream of airflow was supplied to the radiator. We used 100% distilled water in the cooling system. Check out the temperature results below!


Comparison of radiator outlet temperatures in Mishimoto and stock radiators

During our controlled test, the Mishimoto radiator showed an average reduction in coolant temperatures of 15°F–20°F compared to the stock radiator. You will notice that the temperatures seem to fluctuate and spike at similar times on each plot. This occurs because uphill portions of the highway require greater engine loads and invariably produce hotter temperatures.

Radiator efficiency is based on the same data collected in the previous plot, but efficiency is based on a comparison of the radiator inlet and outlet temperature differences. The efficiency number tells us how effective the radiator is at transferring heat (lowering temperatures).


Comparison of radiator efficiency in Mishimoto and stock radiators

The Mishimoto radiator provides a 15% increase in radiator efficiency. This number is a performance value given to represent how well the radiator rejects heat. This efficiency improvement will provide a huge benefit under track and aggressive driving situations.

I would call this project a complete success! Let’s go through the benefits this radiator can provide to your 2015 WRX.

Aluminum Construction
As a standard, Mishimoto radiators are crafted from 100% aluminum. We braze the core to the end tanks so there are no effects from epoxy or glue. Each radiator is TIG-welded and leak tested to ensure a durable and reliable life of service. The use of aluminum provides increased durability compared to stock plastic end tanks. Stock tanks are normally crimped to the stock core and utilize a rubber gasket to seal. Common failures can stem from this seam failing between the core and tanks, or from a cracked end tank caused by repeated temperature variations that weaken the plastic. Additionally, the use of aluminum provides improved heat dissipation compared to the plastic units. This means quicker temperature recovery from high temperatures.

Greater Capacity
The Mishimoto radiator provides more than double the coolant capacity compared to the stock radiator. This increase in capacity has a direct impact on cooling performance, as we saw during our testing. Our engineers designed a specifically sized core to account for space around the turbocharger and the charge pipe for the intercooler.

Dense Core Composition
Following the lead of the stock radiator core design, our engineering team constructed an extremely dense core that features shorter fin height to allow for more coolant tubes. Our radiator features a dual-row design that provides great gains in coolant surface area.

Air Surface Area: 34% increase

Coolant Surface Area: 42% increase


These two increases in surface area result in improved heat transfer that translates into lower fluid temperatures.

Proven Temperature Reduction
Our road testing showed average temperature decreases of 15°F–20°F and radiator efficiency increases of 15%. These are huge gains from our radiator, and we anticipate even greater improvements during track and aggressive driving situations. These efficiency improvements are the primary benefits of upgrading your cooling system, especially if you intend to track your 2015 WRX.

With all of our testing complete, and a very solid product designed, we were ready to enter mass production and close the book on this particular project. We could now move on to additional 2015 WRX projects, including downpipe and cat-back exhaust development.

Swing by the blog for updates on our future projects. Thanks for reading!

http://engineering.mishimoto.com/
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Old 09-05-2014, 07:41 PM   #7
AkRsWagon
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Any testing to see how this affects other systems? Such as any reduction in oil or CVT temps?
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Old 09-06-2014, 02:27 AM   #8
fknkev
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Originally Posted by AkRsWagon View Post
Any testing to see how this affects other systems? Such as any reduction in oil or CVT temps?
I am curious about this as well.
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Old 09-09-2014, 01:43 PM   #9
Mishimoto
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Quote:
Originally Posted by AkRsWagon View Post
Any testing to see how this affects other systems? Such as any reduction in oil or CVT temps?
Quote:
Originally Posted by fknkev View Post
I am curious about this as well.
Great question! We have yet to test the impact of this radiator on the temperature of CVT/engine oil. Being that engine coolant works to transfer heat from these fluids on the FA20, we can assume it is making some impact on overall system temperatures. This is certainly some data we would like to collect in the future.

Thanks!
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Old 09-09-2014, 03:06 PM   #10
AkRsWagon
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Thanks for the answer. I think hard numbers would be awesome to see. I would also assume that it would reduce the temp of these systems. If 15-20 degree cooler fluid is flowing into them, should reduce temps a few degrees at least. Keep up the great work and look forward to seeing the data one day!
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Old 09-09-2014, 04:21 PM   #11
Mishimoto
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Quote:
Originally Posted by AkRsWagon View Post
Thanks for the answer. I think hard numbers would be awesome to see. I would also assume that it would reduce the temp of these systems. If 15-20 degree cooler fluid is flowing into them, should reduce temps a few degrees at least. Keep up the great work and look forward to seeing the data one day!
Thanks for the kind words!
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Old 09-09-2014, 04:30 PM   #12
Mishimoto
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This radiator is now available on our site and through any of our vendors! Check out the details below.



Subaru WRX Performance Aluminum Radiator, 2015+


Product Specs
  • Direct fit for 2015+ Subaru WRX
  • Reduces coolant temperatures by 20+°F (11+°C)
  • 117% increase in coolant capacity
  • 42% increase in coolant surface area (tubes)
  • 34% increase in air surface area (fins)
  • 15% more efficient than stock
  • 100% brazed aluminum core
  • TIG-welded to perfection
  • Included High-Pressure 1.3 Bar Radiator Cap raises the boiling point of engine coolant to provide a safer and more efficient system
  • Includes Magnetic Drain Plug
  • Mishimoto Lifetime Warranty

Tech Specs


Features & Benefits Video

Build-Log
http://engineering.mishimoto.com/?cat=135

Engineering Report
http://lib.store.yahoo.net/lib/yhst-...ringReport.pdf

Images






Feel free to follow-up with any questions or comments!

Thanks
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Old 09-10-2014, 12:41 AM   #13
pbawesome
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Quote:
Originally Posted by Mishimoto View Post

Mishimoto prototype 2 radiator core thickness
Nice Carrera calipers My favorite, such a great deal on amazon.
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