Where exactly does the small vent in front of the hood direct air to on a GT3? I was thinking about putting a GT3 bumper on a C4S to complement a rear GT3 spoiler, but don't want it causing any drag coefficient problems by not having the proper underlying duct work or anything. Is there any duct work underneath? Does it just vent to what would normally be the center radiator? Should I add anything else along with the bumper to make it work as designed? Thanks.

 

It is an exit port for air flowing through the center radiator. In a car without the third radiator, it is cosmetic only. But I doubt there is a measurable amount of drag.

 

Thanks a lot, that was exactly the info I was looking for. For some reason, I thought that perhaps it was an intake for brakes. On that note actually, does anyone know where (or even if) there are intakes for the front and rear brakes on a C4S, and if they can be added?

 

But, you can have the third radiator without the vent also...correct?

Jason

 

Yes, the X51 997S and the tiptronics all come standard with the third radiator. With the standard OEM 997 Carrera nose, there is no top vent.

 

There are no intakes per se. But on the stock 997 (including the 4S I believe) there are a small set of air 'diverters' on the lower front a-arms that channel air to the front disks. You can add (and I have) a larger set of diverters to replace the stock set. They come standard on the GT3 and attach at the same points as the stock pieces. Not sure they add a significant amount of cooling air, but they are a bit larger.
Finally, I'm not sure if it's stock with the non-GT-* models or is part of the GT-3 replacement bumper but there seem to be some duct work under the car and just forward of the front suspension, that helps in the airflow to the front wheel wells. Hope this helps.