986 aero & cooling mods

[BYprodriver]

Anyone consider doing what Porsche did to cool the muffler & install a 03-04 rear bumper cover?

[j.fro]

Originally Posted by BYprodriver

Anyone consider doing what Porsche did to cool the muffler & install a 03-04 rear bumper cover?

Are you talking about the lower treatments here? I thought that was cosmetic.

[BYprodriver]

2003 press info listed the rear bumper redesigned to enhance muffler cooling.

[KRAM36]

Originally Posted by j.fro

Are you talking about the lower treatments here? I thought that was cosmetic.

Unless someone makes a bumper like that tailored to a 2002 and older Boxster, you would need to change out the rear spoiler too.

[woodsman]

Originally Posted by j.fro

Moving on up the car...
Who's had those little air dams in front of the wheels get taken out? Maybe a better question is, who's still got 'em intact?
Here's my mod, fabbed from a special Porsche Tequipment landscape edging:

JFRO haven't you got an old pick-up your workin' on?

[The Radium King]

well, I went to school for such engineering, but even an application of "where does the air go?" works here. quickly, where does the air go from the side radiators? down. where does the air go from the centre radiator? down. we are taking a whole mess of air hitting the front of our car at, say, 100 mph, and deflecting it downwards. think harrier jet. what effect does this have on the driving experience? understeer. from a litigation point of view (ie, after their experience with the 930 and having to remove it from the us market) would Porsche rather have understeer or oversteer? honestly, you want as little air under your car as possible - this is why cars have front spoilers and side skirts. rear diffusers are there to turn what little air does get under the car into downforce.

now then, what does Porsche to with the gt3, gt3rs, gt2? side radiators vent into the wheel wells or out the side of the bumper cover. centre radiator vents upwards. why on these porsches and not all porsches? one is an entry level street car for the unwashed masses, the other is a dedicated track weapon.

I think the fro's comment about the airflow path on his centre radiator is regarding the path the air follows from the outflow of the radiator to the top vent. the gt3rs and gt2 use a duct that requires a bunch of other changes to make it work (spacing out the front bumper, revised side rad ducts to accommodate the fact that the centre rad is moved forward, etc.); without this the flow is a bit more convoluted. however, this would only affect cooling and not aero; less flow through the centre rad is better than a lot of downward flow through the centre rad.

[j.fro]

I'm not an aeronautical engineer, but I was hoping to hear from some. (Thanks, TRK!) My purpose with this thread was to generate some discussion, share what I've done, and see what others are doing. Although I keep insurance, tags, and state inspection on my 986, it's not exactly a street car. It's built to compete in SCCA F Prepared and PCA Improved autocross classes. Winning and losing often comes down to hundredths of a second, so I'm game to try things out to see what works. In a way, it's my hobbyist racer test lab, so if someone can make suggestions, improvements, or point out fatal flaws, I want to know about it.

By the way, I have moved the center radiator out towards the front of the car, and I added ducting to channel air through it and upwards. I don't have data on the aero, but when the car gets moving, the temps drop fast. On hots days at autocross, that's important.

[KRAM36]

Originally Posted by j.fro

I'm not an aeronautical engineer, but I was hoping to hear from some. (Thanks, TRK!) My purpose with this thread was to generate some discussion, share what I've done, and see what others are doing. Although I keep insurance, tags, and state inspection on my 986, it's not exactly a street car. It's built to compete in SCCA F Prepared and PCA Improved autocross classes. Winning and losing often comes down to hundredths of a second, so I'm game to try things out to see what works. In a way, it's my hobbyist racer test lab, so if someone can make suggestions, improvements, or point out fatal flaws, I want to know about it.

By the way, I have moved the center radiator out towards the front of the car, and I added ducting to channel air through it and upwards. I don't have data on the aero, but when the car gets moving, the temps drop fast. On hots days at autocross, that's important.

You are hitting it hard! That sounds sweet. When I finally pick out a front bumper for my car, I'm going to look at doing this. I like the sound of a cooler running car and ducting the air. Very nice!

[The Radium King]

996 gt2, 996 tt and 997 all vent into the fender. if you look behind your rad and in front of your fender liner there isn't actually that much of an opening for the air to flow into the fender given the orientation of the rad.

[jaykay]

Originally Posted by The Radium King

996 gt2, 996 tt and 997 all vent into the fender. if you look behind your rad and in front of your fender liner there isn't actually that much of an opening for the air to flow into the fender given the orientation of the rad.

Yes...and remember in the thread I started on liner vents and how to exhaust into the wheel well and when I said okay how about slots/lovers facing outboard? Had a look at 981 the other day and guess what I saw?

[woodsman]

Originally Posted by jaykay

Yes...and remember in the thread I started on liner vents and how to exhaust into the wheel well and when I said okay how about slots/lovers facing outboard? Had a look at 981 the other day and guess what I saw?

That's what I was thinking, vent it out of the wheel well altogether. The tire wouldn't conflict. The shield at the back of the rad ducts it that way already and there will be no increase in dirt/water reaching the rad.

[woodsman]

The leading edge of this topic would seem to be utilizing airflow THROUGH the body to IMPROVE performance- Ferrari F12(??), BMW etc. And then there's active aero- I'd love to alter airflow to the outer vents based on coolant temps...

[Stroked & Blown]

Anyone have pics of the GT2 or GT3 Cup liners?
I came across this DIY that makes reference to them, but I'd like to see the originals for myself.
http://www.specr53.com/blog/2015/01/08/996-front-brake-ducts-radiator-cleaning/

[The Radium King]

i'd done some research into this previously with the intent to use oem parts on the car. oem would be cool, especially because the part that blocks the airflow out the bottom is also part of the fender liner, so I was hoping that one part would (a) direct the flow into the wheel well, and (b) block flow out the bottom of the bumper cover negating the need for all those flaps that tear-off every 15 seconds).

as noted, the 996 GT2 and TT both have vented fender liners (as does the 997). the problem is, I don't *think* they work on the 986/996 because they are wide-bodied cars so the front end is different (unlike the 986 and narrow-bodied 996 compatibility). at one point I thought that i'd found some GT3 part #s that worked, but I think I was wrong. easiest (and cheapest) is to do what the gt3 guys (and jfro) did - drill some holes. given that the fender liners are a relatively soft plastic, you could most likely press vents into them to get some directional flow if you so desired.

as far as the centre vent goes, i'm going to check to see if I can get it to vent into the wheel well as well - there is a channel that the coolant pipes run in that would allow air to pass from the back of the third rad direct onto the brake rotors with a few artfully placed openings - you would just need to make it follow that path by blocking the front bumper cover bottom openings.

[woodsman]

That's a neat idea but that area is already full of rads, hoses and brackets. Have you had a corner rad out of the car?

[jaykay]

Since the 986 and the 996 have a great deal of commonality, I have wanted to try fitting 996T liners for a while now (I would image GT2's would be far to expensive). I believe the T part number is: 99650412400 (one side). Will they fit??

I believe the GT2 bumper actually sealed the bottom rad exhausts and the 996T had open bottom rad vents, while both had liner vents. So you would likely have still make bottom panels to seal the bottom (provided cooling is adequate).

Here are some visuals:







997:



Maybe those that are not in the frozen north can give this a try after a trip to the local dismantler!

[The Radium King]

i recall now why i didn't do the mod - cost. the standard 996 wheel well liner post -02 is vented:

Linings 02- For Wheel Housing

since they don't have different part #s for the c2 (narrow body) and c4 (wide body, similar to gt3, tt, gt2) then the standard 996 part should work fine. problem is, they are two piece liners, one at $136 and the other at $189; you are looking at $650 for both sides. better just a hole saw. ps, looking at the 996 liner, it vents two ways - into the wheel well as well as down.

[jaykay]

Ouch...I feared as much. I would just use the important front piece .....hope it does not interfere with the rest

[The Radium King]

well well well ...

Pelican Porsche Tech Article - Modifying Your Wheelwell Liners - Porsche 911 Carrera & Boxster - Porsche 996 Carrera (1998-2005)

[The Radium King]

and there's this interesting little graphic courtesy porsche itself: