Strength of Heart - Transmission Cooler R&D, Part 3: Production

This 2015-2018 Dodge RAM 6.7L Cummins Transmission Cooler is now on sale! Click here to check it out!

When we last saw our 2015-2018 RAM 6.7L Cummins performance transmission cooler, it was an aluminum box with 3D prints for ports. In this post, however, we'll be taking that box and turning it into a fully functional transmission cooler. But first, we need to recap how we got here and perform one more test.

In our last post, we finalized our design for our 2015-2018 RAM Cummins transmission cooler. Our performance cooler will use a tube-and-fin core like the stock unit, but to add cooling capacity, we'll be making our core 60% thicker than stock with a 112% larger core volume. We'll be improving the internal structure of the cooler by adding fins to the inside of the fluid tubes.  These fins make the cooler more efficient by adding surface area to the core. The more surface area, the more efficient the core can be. The fins also help move the fluid within the tube, ensuring more of it contacts the cooling surface.

The final step in the design process was to test fit our prototype to ensure it fits without interfering with other components in the cooling stack. Jason once again removed the stock transmission cooler and installed our prototype. Thanks to Jason's spot-on measurements, the prototype fit like a glove - the ports even aligned well enough to install the lines.

With our prototype test fit completed successfully, we were ready to bring our transmission cooler to life. We finalized our drawings and sent them to production to begin building a sample that we could use for a final test fit and performance testing. In a few short weeks, we had our sample in the shop.

Before we moved on to performance testing, we needed to make sure the production sample fit as well as our prototype. So, we brought our volunteer vehicle back into the shop and removed the stock transmission cooler. Jason then slid the Mishimoto transmission cooler in its place and bolted it down. Just like the prototype, our production sample fit perfectly. Jason verified that the lines fit without any issues, then removed the sample for performance testing.

You may be wondering why we removed the transmission cooler for performance testing. Performance testing for our transmission coolers looks a little different than many of our other parts. Instead of installing our transmission cooler and loading the vehicle on the dyno or sending it our for a road test, we use a bench test rig. Our bench test rig allows us to control variables that we otherwise could not account for during a road test. We can control ambient temperature in the shop, airflow through the cooler with our dyno fan, the temperature of the transmission fluid, and its flow rate. Keeping all of these variables constant allows us to compare two coolers accurately, without having to worry about traffic or weather skewing our results. Bench testing also allows us to stress the cooler to its limit, without stressing a volunteer vehicle.

We began our bench test with the stock transmission cooler. Our engineer, Jason, heated the fluid to just over 200°F before turning on the pump and allowing the fluid to flow through the cooler. The dyno fan pushed air through the cooler at a steady 20mph (the average speed of air behind the grille at highway speed). Jason watched as the temperature of the fluid at the cooler's outlet dropped. When the fluid reached a steady temperature, we knew the stock cooler was at its maximum cooling capacity. We then repeated the test with the Mishimoto cooler under the same conditions and compared the results.

Given its massive increase in core volume and overall size, the Mishimoto transmission cooler easily outperformed the stock unit. The Mishimoto transmission cooler was able to bring the fluid temperature down to about 115°F at the outlet, where the stock cooler was only able to manage about 135°F. Inlet temperatures also dropped significantly compared to stock.

With all of our performance and fitment testing completed successfully, we're confident our 2015-2018 RAM 6.7L Cummins transmission cooler will give the heart of your RAM the cooling it needs. We're so confident that we're kicking off production and the discounted pre-sale. So, head over to our website for more details and to keep your RAM's transmission cool, and as always, let us know what you think!

Thanks for reading!
-Steve