3D Printing an Oil Cooler Duct With BD Engineering

Now the duct is ready for paint.  It needs a few coats of primer-surfacer and more sanding before the base and clear coat can be applied.  We went to Bells Autosport in Huntinton Beach California to help us with that.  The guys at Bells are total gearheads and they get what needs to be done on unusual projects like ours.  They are not afraid of custom work like many production body shops and you can see that they have many times the business of the other body shops on the same street!

We got our part back from Bells with a beautiful paint job.  If the paint doesn’t quite match the OEM part in the pictures, it is because the OEM part has yellowed PPF on it from a few years back!  Bells matched the paint on the noncovered edges of the OEM part.

Here is our new oil cooler duct compared to the OEM STI foglight cover.  The duct even has the same styling features.

The duct is very unobtrusive on the front of the car and looks like a factory part which matches our car’s sleeper theme.

In a close-up view, you can see the perfect fit of the duct.  It snaps in place with authority, not like the stock part which feels like it could fall out.


  1. The trouble with the Aesub spray is it is pretty pricey at $40 a can. Back when I last did a scanning project a couple years ago it was closer to $60. I ended up using Magnaflux SDK-S2 developer which was a little better at a little under $30 a can, but still expensive. It doesn’t evaporate on its own, but leaves behind a chalky residue that is easy to clean up.

    That said, it seems the real budget option is to go for talc, corn starch or baby powder mixed with rubbing alcohol. I haven’t had a chance to try this myself, but plan to use it at the next opportunity.

    1. The disappearing feature is pretty good for me and worth the price to me especially when doing stuff like suspension, brakes and inside of the the core support, the cleanup would take a long time.

  2. That’s really cool, what a great use of 3D scanning and printing. I’m really glad you guys showed how much work goes into finishing a printed part to an OEM level finish. The finished part turned out great!

  3. > This is really cool and we will probably have to run the stock cover for winter driving to avoid overcooling the oil!

    Is there reason not to run an oil thermostat sandwich to the cooler to avoid overcooling?

    Great article!

    1. I don’t like them as they can restrict flow, however, the Greddy cooler uses one. I am not sure what temperature it opens at.

    2. On Project S2000, I had to cover up some of the front bumper airflow opening in winter taking the highway to the track to reduce airflow to the oil cooler. Even though I had a Mocal thermostatic sandwich plate, it still always flows some oil. If the oil in the oil cooler were completely cut off, then it would be very cold when the thermostat opened up and could thermally shock hot components it comes in touch with.

  4. What polymer was the component printed from? Fantastic work on getting the fitment and then surface finish so good.

Leave a Reply

Your email address will not be published. Required fields are marked *