Almost a decade ago we implemented airflow splitters in our 8th & 9th Gen Civic Si turbo kit intercoolers to help evenly distribute airflow across the intercooler core. Over the past few years we’ve been asked why this same concept wasn’t integrated into our intercooler upgrades for the newer Hondas. CFD analysis allows us to accurately show and explain why we chose to leave dividers out of our newer designs.
Tight spacing constraints of the 8th & 9th Gen Civic bumpers forced us to utilize a relatively tall, 22x11x3” intercooler core to allow for 600+ horsepower airflow capability. Even airflow distribution throughout the “tall” core would be critical in terms of performance, especially at higher power levels. Newer Honda models such as the 1.5T Civic, Turbocharged Accords and FK8 Civic Type-R have a bit more room to fit 3.5 – 4.0” thick intercooler cores (at approximately 7” in height), so we are no longer forced to accommodate core volume with height to allow for similar airflow capabilities. Our engineers put together a CFD analysis of our 2017+ Honda Civic Type-R FK8 Intercooler upgrade with a velocity boundary condition of 100 m/s and a pressure boundary condition of 103 kPa to simulate approximately 15 PSI of boost. After inspecting the flow streamlines, it can be seen that flow distribution is extremely uniform and very laminar. Under close examination, it can be seen that there is a marginal amount of turbulence between the flow channels in the intercooler core. This minimal turbulence does not disrupt airflow in any way, nor does it amount to a measurable difference in horsepower. Our billet end tanks promote a much more laminar streamline profile due to our machining process, as well as a more uniform flow distribution than other competitors that may or may not include airfoil-shaped flow splitters inside of the internal end tank geometry. The end tanks used in our 10th Gen Civic and Accord platforms feature a more compact, yet robust design, which evenly distributes the compressed air entering the core flow channels. We have concluded that flow splitters inhibit uniform laminar flow in smaller/shorter end tank designs.