Testing Plans

As mentioned in the previous segment, we will test four different coolers.

• Stock intercooler
• Mishimoto bar-and-plate prototype 1 (larger internal bar height)
• Mishimoto bar-and-plate prototype 2 (smaller internal bar height)
• Mishimoto tube-and-fin prototype

For each cooler we will be collecting data for temperature, pressure, and power output. Each cooler will be tested repeatedly until we have three consistent runs producing data as accurate as possible.

Below is a look at the three different core types that will be tested.

To collect temperature and pressure data, we installed two sensor bungs in each intercooler boot. This will allow us to evaluate these numbers pre-intercooler and post-intercooler for an accurate comparison.

Time For Testing

Once we had a plan for the testing process, we set the Fiesta up on our Dynapack™ and prepared our intercoolers.

Swapping coolers was a relatively quick process for our team, as we have become adept at bumper removal.

Pictures can show only so much. How about a video showing a couple pulls?

Initial Testing Data

Time to review our findings. Now, our first measure of heat exchanger performance is heat transfer. This will be a comparison of intercooler inlet and outlet temperatures for our four tested intercoolers.

These data points immediately reveal the inefficiency of the stock intercooler. Inlet temperatures for the stock cooler begin at around 160°F and rise to 225°F. Outlet temperatures at the start of the pull are ambient (62°F) and quickly rise to around 80°F at the end of the run. This is not a massive inefficiency but can certainly be improved.

Now let’s take a look at our prototype coolers. Inlet temperatures sit at around 5–10°F below the stock cooler. The big change here is in outlet temperatures. Despite the rising inlet temperatures during the runs, we recorded ambient outlet temperatures for all three prototype cores. Although this would not be considered a torture test of the coolers, the results do show a big improvement over the stock cooler.

As we’ve noted previously, heat transfer is directly related to internal core flow. Our prototype cores are more restrictive than the stock core, which is how we achieved the temperature drops. We recorded pressure at both the inlets and outlets to compare these values as well.

This is the plot that will have the biggest impact on our decision. The stock intercooler is rather unrestrictive and free flowing. From one side of the cooler to the other, a maximum drop of 0.9 psi was recorded. Again, this explains why the heat transfer is not efficient.

Our very dense bar-and-plate prototype 2 was a serious outlier in this test. Pressure drop numbers exceeded 3 psi, which is quite high for this tiny turbocharger. This particular core was eliminated.

One bar-and-plate prototype and one tube-and-fin unit remained. These cores feature a similar internal fin density despite being different core types. They produced a similar pressure drop, right around 2.5 psi.

In addition to our pressure and temperature data, we also collected our power output data for each core.

Our plots showed gains in the top end of around 5–10 whp and wtq with each of our prototypes. These gains occurred possibly because of the lower intake temperatures.

Coming Up – New Prototype Testing

We are not exactly satisfied with these results. Temperature and power data are great, but we are not pleased with the pressure drop numbers. We are planning to design two more cores with varying internal fins that we hope will produce a better compromise between temperature and pressure.

Our goal is to bring pressure drop closer to the stock cooler while still maintaining efficient heat transfer.

Keep an eye on our blog for other updates on awesome new Fiesta ST performance parts!

Prototype Ford Fiesta ST Intercooler Fabrication

Timing is a bit of a concern for us at this time. This project has been lengthy, but it will be worth the effort and time when we know our best efforts have been captured in our final product.

Our final version of this intercooler will likely feature a tube-and-fin core. The benefits of weight and airflow are too important to ignore, not to mention the temperature drops we are seeing with a strategically designed internal core.

For our team, the creation of a bar-and-plate cooler is a much quicker process. We’ve found that pressure drop between the two core types is similar if fin style, density, or both are the same. So for this test, we are using two bar-and-plate cores to determine our final fin design that will produce improved internal airflow.

Check out our two cores!

Both cores are less dense than the previously tested units, so they should produce a lower pressure drop. They also utilize different fin styles. Check out the internal structures below.

The core on the left has a loose fin composition and uses standard straight fins. The core on the right uses offset fins, meaning the rows are offset to provide greater contact surface area. Offset fins also result in a slightly higher restriction.

To conduct testing for these cores, we needed to attach our end tanks. With time constraints in place, we decided to use the end tanks from our rejected prototypes.

Once separated, the powder coat was removed so we had a clean surface for welding.

Our talented fabrication team then laid down some impressive welds to finish the prototype fabrication.

Coming Up – Additional Testing

Next time we will be testing these two new prototype intercoolers on our Fiesta. Based on the data we collect; we should be able to start producing our first batch of coolers soon.

Keep an eye on our blog for additional updates on upcoming Fiesta ST performance parts.

New prototypes were constructed, and we were ready to make some dyno runs.

These dyno runs included two prototype cores, which were compared to the stock intercooler. Although both cores are of the bar-and-plate style, we intend to use this data to finalize our tube-and-fin intercooler. We saw higher pressure drops with our previous round of testing, so with this testing, we hope to determine the optimal core density that will provide an ideal compromise between pressure drop and heat transfer.

Pressure Drop Data

First, let’s take a look at the pressure drop numbers from each of the cores we tested during the development of this cooler.

This plot is a bit much to take in at once. Below is a quick chart showing the average pressure drop for each cooler we tested.

As you can see, prototypes from our first round of testing showed far too much pressure drop. Although this translated into massive temperature drops, we wanted to see if we could provide a better blend. Our second set of prototype cores showed much more promising pressure drop data that hovered right around the average of the stock cooler.

Temperature Data

The data collected above show very promising pressure drop numbers from our third and fourth prototype cores. As long as these coolers provide improved cooling benefits, we can consider them for our final core selections. Let’s jump right to the temperature data.

The chart above clearly depicts a serious difference in cooling ability between the tested cores. The stock unit performed worst among the three cores. The fourth prototype core improved slightly over stock, while the third prototype design showed very impressive heat rejection.

The data above are summarized in the chart below.

One of the key columns of this chart shows the rise in outlet temperatures. Our fourth prototype is a slight improvement over stock; however, the third prototype is essentially unaffected by the pull. We see barely any temperature change during the test.

Can you guess which core we selected?

Our third prototype provides a 20-degree drop in outlet temperatures while resulting in only a 0.2 psi difference in average pressure drop during a pull. This prototype will be a tube-and-fin cooler in its final design. It will be a lightweight cooler that still allows ample airflow to the radiator for engine cooling.