Pedigreed Power – Performance Intercooler for 2019+ RAM 6.7L Cummins
After reading an article in a trade journal claiming the diesel engine would never be successful on the road, Clessie Cummins, founder of Cummins Engine Co., decided to take that statement as a challenge. In a used Packard limousine with a Cummins engine swap, Clessie and his chief engineer departed Indianapolis for the 1930 Automobile Show in New York City. They faced hundreds of miles of rough roads and terrible winter weather but arrived on time and with a fuel cost of just $1.38, only to be barred from entering the show because Cummins hadn’t registered in advance.
Stock Evaluation
To determine where improvements could be made, Ye, our engineer, started with a careful evaluation of the stock intercooler. Mounted at an angle in front of the condenser, the stock intercooler is 25” x 17” x 5.3” with a 25-row tube-and-fin core. It seals against the lower bumper fascia and the radiator and uses plastic deflectors on each side to force air through the opening on the bumper.
Design Process
Ye’s first step in designing a superior intercooler was to opt for a bar-and-plate style core. A bar-and-plate core uses solid aluminum bars and plates stacked together to form the internal and external air passages, as opposed to thin extruded aluminum tubes. There’s a few benefits to this style of core, namely the ability to support much higher boost pressures and increased durability against damage from debris and repeated heat cycles.
However, the bar-and-plate core presented a problem that the stock intercooler didn’t—increased weight. To resolve this issue while maintaining the factory mounting points, Ye included two heavy-duty rubber isolators to replace their stock counterparts and ensure a secure, direct-fit installation process.
To distribute airflow evenly across the intercooler core, Ye incorporated two internal air diverter plates inside the intercooler end tanks. In addition to evenly guiding charged air across the core, these diverters also reduce turbulence within the end tank, ultimately reducing pressure loss.
With our larger core size, the gap between the intercooler and the bumper was smaller than stock, meaning the stock deflectors no longer fit. Ye successfully redesigned these pieces to retain coverage of the gap and optimize airflow.
To maximize flow and durability, Ye also included hot-side and cold-side powder-coated aluminum piping with Mishimoto Silicone Boots and Constant-Tension T-bolt Clamps. Not only do these complement the overall aesthetic of this intercooler setup, but they provide superior heat resistance for a longer overall lifetime.
Testing
Unlike Clessie Cummins, our testing process didn’t involve shoving our intercooler into a Packard limousine and driving halfway across the country. Instead, Ye turned to our DynoJet dynamometer to put our intercooler to the test.
Once our RAM was mounted to the dyno and warmed to proper operating temperature, Ye gathered data on both the stock and Mishimoto intercooler using two temperature sensors and four pressure sensors. Multiple runs were conducted on each intercooler to perform heat soak testing.
To perform each test, a cluster of five to six RPM sweeps were conducted back to back, leaving each intercooler no time to cool down. These conditions simulate a heat-saturated environment that push the intercoolers to their limit, typically far beyond the conditions observed during heavy towing or off-roading.
During these tests, similar inlet temperatures were maintained for both intercoolers. Ye found that our intercooler demonstrated a 20°F lower outlet temperature compared to stock, indicating that the Mishimoto intercooler successfully outperformed the stock unit.
Next, Ye took a look at the pressure data between the two intercoolers. Data revealed that our intercooler reduced pressure drop by 1.6psi compared to the stock system. This lower level of pressure drop is due to the reduced airflow restriction of our design, which is a result of the widened internal flow path of the core and oversized piping.
The reduced airflow restriction was further demonstrated when Ye performed flow bench testing. This test was important to conduct in addition to our dyno testing as it removed air density change as a factor and allowed us to confirm our intercooler’s superior flow. This test revealed that the Mishimoto system demonstrated 44.7% less restriction than stock.
Ye’s next step was to take the data gathered from the heat soak testing and run two mathematical computations to get an even better sense of how our intercooler performed.
The first computation was to determine intercooler efficiency, which is a measure of how effectively an intercooler cools the air passing through it. Instead of simply comparing the outlet temperatures, intercooler efficiency accounts for both the inlet temperature and the ambient temperature when testing was conducted. By plotting intercooler efficiency throughout the entire testing process, a more accurate picture of cooling performance is revealed. The chart below shows the results of this computation and demonstrates that our intercooler not only performs better than stock, but it also performs better for longer.
The second computation was to determine charged air density change. This measures the intercooler system’s ability to cool charged air, which directly translates to engine performance. In other words, the denser the air, the more oxygen that’s delivered to the combustion chamber to burn—resulting in more power. This is calculated with temperature and pressure data at the turbo outlet and intake elbow. From this computation, Ye was able to determine that our intercooler increased charged air density by a maximum of 237% compared to the stock system’s 162.6%, further demonstrating the superior performance of the Mishimoto system.
By and large, testing revealed that our intercooler greatly outperformed its stock counterpart. That’s in line with what we’re determined about here at Mishimoto—taking something good and turning it into something great. With a robust bar-and-plate construction, increased core volume, and demonstrated cooling properties, the Performance Intercooler Kit for the 2019+ RAM 6.7L Cummins is the ideal upgrade for those looking to take their truck up a notch. Whether you’re determined to tow heavy loads, tackle the trails off-road, or simply make your RAM the best it can be, this kit is ready to help you take the next step.
