2016+ Honda Civic Intercooler – Cast End-tank Design Pt.3

It’s time for another project update on our Performance Intercooler Kit for the 2016+ Honda Civic. As promised in the Honda Civic FMIC Kit Part 2 Blog, we are now going to dig into the design of the cast end-tanks on the 27WON FMIC.


Before we get into flow simulation of the end-tanks we need to quickly talk about general fitment of the intercooler. The front of the Civic has an abundant amount of room for a larger intercooler but with the intent of maximizing this intercooler upgrade; fitment and spatial constraints are still a large concern. The 27WON team went through the process of scanning the OE intercooler and then through multiple design iterations of core size and end-tank designs that were 3D printed and test fit on the vehicle.  Upon doing so we were able to determine the largest intercooler while maintaining an OE style mounting.

As you’ve likely come to notice by now, OE fitment is important to us. It’s important to a hassle-free modification of your car.

With that being said let’s focus on cast end-tank design because that is where the magic happens.

For the CivicX platform, the 27WON intercooler end-tanks have a few key design considerations:

1) Charge/Boost Airflow Control – This is the boosted airflow from the turbocharger and how it distributes into the intercooler core.
2) Mounting – The 27WON design retains the OE style mounting and brackets.
3) Ambient Airflow Control – Unique to the 27WON Design, the end-tanks incorporate ducting fins to helps direct ambient air through the intercooler instead of around it.

In this blog, we are going to focus on point #1. Points #2 & #3 will be covered in the next blog.

Check out these CAD renderings of the intercooler inlet end-tank. These are just a handful of the design iterations that went through flow simulations during the design process.

You might be wondering “What is the purpose of the fins?” That’s a great question! Since this is the intercooler inlet end-tank; this end-tank has the function of dispersing the airflow into the intercooler core. For the intercooler to perform at peak efficiency the airflow through the core must be evenly distributed…this is the function of the fins.


Here you see two very different configurations…”no fin” vs a very unique “airfoil” style fin.  The “no fin” design will allow the air to flow wherever it likes vs the “airfoil” fin will help direct the path of the airflow into the core.  

Let’s look at the flow simulations that follow:

Flow simulation as seen without an internal fin

Flow simulation as seen without an internal fin

No Fin Flow Simulation:

A ‘no fin’ end-tank is standard in the market. This design path will work but it leaves a lot of performance on the table. This lost performance is due to the nature of air (aka Fluids). The airflow through the core will always take the path of least resistance. With no fin to help direct the airflow the air will flow primarily through the center of the intercooler and will decrease in flow as you approach the top and bottom of the intercooler. This drastically reduces the peak performance potential of the intercooler.

Looking at the intercooler core flow simulation you will see a color gradient. Blue is low velocity airflow and green is high velocity airflow. You can see that the center of the core is primarily green and the top/bottom of the core is primarily blue. This tells us airflow is not evenly distributing through the core and thus performance is not going to be maximized. In a nutshell, this design is not effectively utilizing the entire core and therefore it functions as if the intercooler was smaller than it truly is.  

Now let’s look at the “airfoil” style fin.

Flow simulation as seen with 27WON internal fin

Flow simulation as seen with 27WON internal fin

Airfoil Fin Flow Simulation:

After multiple design iterations, the 27WON team came to a unique “airfoil” fin design. Just as in the above analysis, there is a color gradient that represents the airflow velocity through the core. By adding a fin to the inlet end-tanks, we were able to better direct the airflow into the core. You will notice how the color gradient is much more uniform across the full surface of the core. This means we are getting more even airflow through out the entire core which means we are using the full surface area and this will help maximize the peak performance potential of this intercooler design. This design will outperform many larger intercoolers.


Let’s wrap up this installment with the outlet end-tank. Through flow simulations, we’ve found that the outlet end-tank design is not as critical and influential to the overall performance of the intercooler. Controlling the airflow into the core is much more important than controlling how the airflow exits from the core. Our outlet end-tank design went through multiple iterations to find the right balance of volume and airflow control. We found that a fin in the outlet end-tank was not necessary and only complicated the design and manufacturing.

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