Redirect airflow from center radiator

[The Radium King]

um, i think you folks fail to recall that the base 986 came without a centre rad and spec racers have no issues with brake cooling.

and that when the centre rad was introduced on the 's' model, no additional aero was added. so, from an aero perspective, the addition of the centre rad on the 's' model provided front end lift on a car that previously did not have it - you are taking air approaching the car at a high velocity and redirecting it downwards. this will lift the front. worse, you are introducing air under the car which will lift the entire car.

assuming the 986 spent lots of time in the wind tunnel and was the epitome of porsche aero engineering, the hack addition of the third rad was an aero compromise to address heat management of a large engine in a confined space.

regardless, what is the worst that could happen from redirecting the air upwards? more front traction. worst case - the rear will feel lighter as a result. it will not be lighter, but will feel so comparetively. what to do? change how you drive, get wider rear rubber, whatever. if you are on a quest for performance, it is foolish to compromise one aspect of your car to accomodate inadequacies of another.

otherwise, there will be less air under the car = less lift overall. not a bad thing.

to the op - i think you can use the gt2 duct but would have to trim your side rad ducts a bit. otherwise, you can keep the centre rad in it's oem orientation and just push forward and tilt using threaded rod and spacers. i would like to see the link you are referencing; the one i am aware of is on the 6 speed forum and includes the install of the gt2 front bumper cover which has the taller/narrower side rad openings. and it is hard to copy the gt3 rs install as they didn't use the gt2 duct iirc.

[Robert986]

You are absolutely correct TRK!

When it comes to actual aero performance, I can say that at 150Mph it becomes REALLY light in the front, not very planted I´d say. Besides the top vents I´m also adding a decent splitter, I think it will be just about right. Pics will come when I´m done! :-)

Regarding the other thread I´m referring to, I hope I´m allowed to share links to other forums, if not please let me know. Here is that thread anyway, there is a guy (jimk04) who has made a really neat installation, however I believe that it´s a bit too tight behind the rad, so I doubt its optimum from a aero perspective. http://www.planet-9.com/987-cayman-and-boxster-competition/208657-center-radiator-venting-holes-question.html#post2011233


TRK, you are correct, the GT2 duct can be fitted as intended if the side ducts are trimmed, to rough for my taste, wanna keep the side ducts neat and tidy.

Anybody with opinions on the tilted rad? Air bubbles or not?

[jaykay]

Re light front.....what is your ride height? Stock ride height and damping will feel very light and nervous at 150. Lowered on coil overs should help

[Robert986]

Wow, great inputs guys!

I like the J.fro approach to extend the hoses, I feel that a flipped radiator is asking for problems with trapped air in the radiator.

Btw. I Think that the 996 and 997 chimneys are the same parts: 996.575.325.30.
The splitter I´m adding is the 99650598691, actually intended for the 996 Mk2, but I hope I can make it work.

I´ll sure let you know how it turns out, right now I´m busy replacing a side radiator that had a leak. The bumper cover is at the paint shop so soon I hope to have it all put together.

[Robert986]

Originally Posted by jaykay

Re light front.....what is your ride height? Stock ride height and damping will feel very light and nervous at 150. Lowered on coil overs should help

Good point, It´s on my list, however I try to do one thing at a time to trick myself to forget the cost for each step.. ;-) Also want to verify front clearence with the new splitter Before I decide on lowering.