Mazda Miata (NB) Oil Cooler R&D, Part 2: Oil Cooler Shroud and Duct Development
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In our last segment, we outlined the goals of the project, and we started fabricating mounting brackets to position our heat exchanger under the front of the Miata NB (second generation). We also hinted at the use of shrouding to direct airflow properly through our cooler.
Optimal airflow through a heat exchanger is vital to the efficiency derived from an oil cooler system. In addition, we see value in retaining the stock engine undertray, which aids in the proper regulation of coolant temperatures. We will build our air duct into the undertray, with the goal of a stock-like appearance on the top of our list, right next to optimal airflow.
Air Duct Fabrication
First, we needed to create some space to fit our ducting. We ordered a stock undertray so we could make some cuts for our cooler.
A couple of cuts later, and our cooler was now visible with the tray installed.
Done! Plenty of space for fresh air to enter our cooler. What’s next? We need to tackle some ducting to guide airflow through the core and eliminate any gaps between the cooler and undertray.
Instead of starting with fabrication, we hit the computer and created a 3D model of the components that will attach to this duct. By designing the duct in 3D first, the fabrication process becomes quicker and more precise.
The templates shown below were printed out once we had a final design in Solidworks.
As you can see, the templates map out the cuts, holes, and bends necessary to create this piece. We glued these templates to our steel sheet and start the process of fabrication.
After some time in the shop, we had a completed prototype of the duct for the heat exchanger. Check it out!
Looking good so far! Next, we needed to work out a shroud that mounts to the undertray, which will enclose the duct and reduce the chances of improperly routed airflow.
We hit Solidworks once again and came up with a solution in 3D, which was printed out in template form.
Cuts and bends left us with the result seen below!
Due to the location of the bend shown in the image, we needed to cut out this portion of the shroud, bend the material, and then reweld the piece.
A few more adjustments were made to perfect fitment.
We then attached our shroud directly to the undertray, creating a nice fit between the duct and the shroud. This setup also allows for the undertray to be removed without affecting the heat exchanger.
Awesome! This setup looks great. The shroud and duct will both have a black powder-coat finish, which creates a subtle, stock-appearing setup. It will be interesting to see the temperature drops once testing is conducted.
For some extra protection against damage from road debris, we are planning to add some steel mesh into the design. Check out the mock-up with one of our potential material choices below.
We will also be adjusting the hardware used to attach the shroud to the undertray. More on that coming soon.
We’ve reached the point where we can install our sandwich plate, oil lines, and testing sensors for data collection. Check back next time for our first round of product testing!
Thanks for reading!