The idea of replacing the foglights with some type of duct is something I have thought about for a while, but the task of making a suitable part for this seemed to be fairly difficult and I put the project on the shelf.
Production and Install:
This implementation of the concept is well done and even though I missed out on the latest revision to the design, I have version 4 and version 5 is the current design, the part fits with some coaxing and the addition of a new hole to secure it in place.
The idea of the duct is to utilize these openings in the front bumper cover to direct air to a brake cooling system or an intake.
My goal is to gauge if there is positive pressure inside the duct that can be leveraged to increase airflow to an intake. To measure the static pressure inside the duct I made a cap to seal the discharge opening and placed an averaging flow sensor (AVS) inside the duct that is configured to measure statice pressure.
A pair of zip-ties worked well to hold the cap in place completing the duct installation to the bumper cover.
Once the bumper cover was reinstalled on the GTI a pressure line from a differential pressure sensor was attached to the AFS.
The pressure transmitter is wired into a DATAQ DI-149 data logger to measure the inches of water of static pressure inside the duct while driving the GTI.
With the bumper cover back in place the AFS installation is inspected.
The first test was made with a fan and a standalone differential pressure device.
Without any airflow, the gauge shows right around zero (0). There’s a minor fluctuation of about +/- 0.01″ of H2O. With the fan on the highest speed and placed up against the bumper the static pressure increases to 0.1″ of H2O.
The amount of pressure increase was less than I was hoping for, but a drive on the street would provide more meaningful results.
Pressure readings on the street were higher than with the fan.
A foglight duct was made and then installed on my GTI along with a pressure sensor to determine the amount of static pressure inside the duct during street driving.
Measurements show a small increase in the static pressure inside the duct. This pressure increases with an increase in the vehicle speed.