Hood Louvers - Design and Theory
There is a lot of misconception about the purpose of hood louvers, and where to place them on your car for the best results. Unfortunately we see a lot of people placing their louvers in a location that will actually suck air into the engine bay, causing over heating and front end lift. The purpose of these hood louvers is to vent hot air out of the engine bay to help avoid over heating your car at the track.
Venting the hot air out makes your heat ex-changers more effective(radiator, intercooler, oil cooler) by allowing more air to be pulled through them. As an added bonus it will increase the downforce on your front end, win/win. It's important to note that the louvers need to face towards the back of the car to let hot air out, and they should run perpendicular to the air flow. You can run vents at an angle if needed, but it's not ideal.
In order to find the best location on your hood, you must analyze the high and low pressure zones. Your goal is to place the vents in the lowest pressure areas if you are trying to vent the hot air out. High pressure pushes air in, which again is the opposite of what we want. To analyze the pressure, you can use a Magnahelic gauge, but we won't go to far into what that takes to do. For the simplest understanding, just remember:
High Pressure = Air going in
Low Pressure = Air going out
With all of that in mind, hood louvers are a very simple but effective addition to any car that's driven hard.
Check out this short video, you can see by the direction of the yarn that the air is in fact flowing out of the engine bay. This video was slow speed, we only accelerated to ~40mph