Flow testing intercoolers has been an ongoing effort since shortly after I became an owner of a GTI. Recently I found out another local GTI owner had a CTS intercooler sitting in their garage with no plans to install it and I was able to get it over to my garage to perform a flow test.
For this flow test the bench calibration is checked and then the intercooler is attached using the CTS silicone outlet hose. On the inlet side the CTS hose is used along with a bell-mouth to promote smooth airflow into the intercooler.
The flow bench is operated at a test depression of 28″ of H2O and the airflow through the intercooler is measured at that pressure drop.
The CTS stock location intercooler flows 211 CFM at 28″ of H2O. This is shown on the following chart along with other stock location intercoolers:
The CTS intercooler results are compared with all other intercoolers that have been flow tested in the following chart:
The CTS stock location intercooler flows 211 CFM at 28″ of H2O. This places the CTS IC in the lower middle range of the stock location intercoolers that have been flow tested and in the middle of the range of all intercoolers that have been flow tested.