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Cooler Than Winterfell – Intercooler R&D, Part 1: Stock System Review

George R.R. Martin isn’t the only author who can write some gripping stuff about the cold. That’s right, brace yourselves, winter is coming; and we are jumping into the frigid waters which we know well – improved intercooler performance. The patient going underneath our scalpel for R&D is the 2013+ Ford Focus ST, but per our usual process, let’s first take a brief second to examine the stock system.

Our Ford Focus ST intercooler on our surgical table
Our Ford Focus ST intercooler getting inspected

Ford decided to use tube-and-fin construction for this intercooler instead of bar and plate. The difference between the two is pretty simple. Tube-and-fin intercoolers are more commonplace amongst stock applications. They are lighter and promote greater airflow through the core exterior. The trade-offs to these qualities are less heat transfer and more susceptibility to road damage.

Bar-and-plate intercoolers, however, have increased cooling efficiency over a tube-and-fin design. They are physically a stronger intercooler, meaning they can withstand more direct damage. The drawback here is weight. The greatest strength over tube-and-fin is a blessing and a curse in the sense that it has more thermal mass to work with, but it is a heavier item, adding some front end weight to your ride. Also, although it has a thicker core, this means more resistance to airflow than a tube-and-fin design. The core choice depends on which application the design is for, but those are the facts.

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Ford Focus intercooler pipe inlet

Back to the intercooler at hand. This unit has a height of 6 inches, and a width of 2.5 inches. From end tank to end tank, the length measures at 26 inches. Speaking of end tanks, these are constructed of plastic and we intend to fix that. As we all know, these end tanks are in a constant state of flux between hot and cold. This doesn’t bode well for the plastic because it can weaken over time, causing cracks in the surface, which would lead to – you guessed it – boost leaks. No one likes a boost leak. So we plan to incorporate aluminum end tanks to prevent this from ever happening.

Look closely, you can see the details of the tube-and-fin design
Look closely, you can see the details of the tube-and-fin design

Upon inspection, our engineer has also noticed that this intercooler has a fairly loose core construction. This means that fins inside the core are spaced relatively far apart. This is often the case with factory intercoolers, and there isn’t anything fundamentally wrong with that. We are just going to improve it with a tighter core construction to allow for more heat transfer.

What’s Next?

Something is missing here!
Something is missing here!

The intercooler is out, so we will get to work on some design ideas. We are going to sample a few different designs and sizes to find the best balance of heat transfer, pressure drop and improved airflow. I’ll dive deeper into these aspects of the design in the next update. Thanks for reading and stay tuned!

-Diamaan

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