nwGTS

I came about a pair of 997 GT3 front brake spoiler ducts and decided to swap out the ducts on my GTS for MOAR POWER.

After taking the wheel off I noticed the GTS's brake duct looked... substantial. After unhooking it and removing it I laid it down side by side with the GT3 ducts and found this:

GTS duct on top. GT3 duct on bottom.


The GTS's duct is almost twice the size of the GT3. Granted the GT3 has a few vanes to direct the air a bit more precisely but the GTS's duct looks like it would funnel 70-80% more air.

Here's they are laid over one another:




It's very clear. Based on this discovery, I elected to keep the GTS's original brake ducts and instead spent the time inspecting suspension and brake components, cleaning and tidying things up behind the wheel wells.

So, there's a lesson here. 'Upgrades' aren't always that.

IslandS52

Since my Carerra S is lacking even these smaller ducts, I'll take the Gt3s off your hands.

NAM VET

as owner of a GT3, our cars are substantially lower, and cannot fit a much deeper front brake duct.

all the best.....

mdrums

As I've said sooooo....many times before on this forum...A Carrera based car and a GT3 based car funnel air differently in the front. Also the only brake duct upgrade is the GT2 brake ducts and those are $250.

nwGTS

After speaking with an engineering friend of mine we think that may also be a possibility as to why it is smaller, but still doesn't explain the smaller surface area of the GT3 ducts above the floor pan. We actually think they are smaller because there is simply less air moving underneath a GT3. So, what is there, needs vanes to direct it. Whereas, the GTS has much more air flowing underneath the car allowing it the option to route that greater volume of air more effectively. Otherwise, we're clueless.

bml376

I have 996 cup car ducts on my 997.2. Prior to this I had the GT3 ducts shown in previous posts. I don't have a very scientific way to measure airflow between the two I've tried, but the cup car ducts have a much bigger surface area and extend much more (closer to the ground) compared to the GT3 ducts. With these ducts and so far no other brake mods I don't feel as much brake fade on track. But like I said its not scientific and could also be due to changes in my driving style.

Here are how the cup car ducts look when installed on my car.

nwGTS

It's interesting you say your first point because in fact after looking at a 997.2 GT3 car later today I saw the front undertray (between the front bumper cover and mid-undertray) of the GT3 and my GTS are identical. They both have an identically shaped tunnel on either side of this undertray that lead to the brake spoiler duct.

So, in fact, the front splitter on the GT3 is the only different piece if looking at the car from the underside.

Here's an undertray shot of fellow Rennlister Edgy01's CS:



Here's a shot of the undertray of a 997 GT3:



They were identical on the car I saw today too.

Very interesting.

scorcherjf

This is the exact same thing I saw with mine when I compared the GT3 ducts to the GTS.

Porsche balanced the GT3 as a whole package so perhaps they simply need less air flow to the brakes because they're bigger and can cool via surface area rather than just relying on massive airflow. Also, having smaller ducts creates less disruption in the air travelling underneath the car which might balance out the aerodynamics better with the GT3's front lip and wing. So perhaps they thought they simply didn't need that much cooling via ducts so they could minimize aero drag and turbulence?

floatingkiwi

I have a 997.1 C2S with aerokit (different car I know), but I changed to Gt3 ducts on my car and caliper temp stickers subsequently told the story of much better braking balance front to back. Instead of being a large heat difference between front (v hot) and back (not hot), they became more equal. In fact so much so that I think I now have too much front cooling for road work. using PFC 08.

Carmichael

Hmm, I wonder if the GT3s will work on my car ...

AWay

I went through this same thought process a few months ago regarding the ducts.

Bottom line is the GT3 has different front fender liners (which I've upgraded to) and already direct much more air in the top area where the GTS ducts have more surface area. See photo of my liners (GT3) attached and note the large top duct directing air from the radiator. These top ducts are of course absent on the 'regular' Carrera's as they vent their radiator air to the outside of the wheel housing.

GTS ducts would not fit on a GT3.

nwGTS

The GTS ducts would fit on a GT3 just looking at your picture and what I saw on the GT3 I examined. The GTS duct would fit around the trailing arm and the steering tie rod end would go through the hole on the top part of GTS duct. In fact, they would probably close off that entire open area around the steering tie rod end. However, that may be a bit redundant or even unnecessary given the directional guidance of the radiator air from the outlet duct the GT3s have. I didn't think those upper ducts would be used for brake cooling since the air coming from the radiators was... well.. hot. It looked like it just helped it escape the wheel well more efficiently eliminating turbulence and drag.

AWay

I would politely disagree that the GTS ducts would fit with GT3 fender liners. There just isn't much room between the air scoop and the lower brake duct to accommodate the larger GTS top section. I uploaded a clearer photo and maybe it will help depict the spacing better. Realistically though, not many folks are going to have these GT3 fender liners installed, so no great worry either way.

If I were only replacing the factory lower ducts I would probably use GTS parts versus the typical GT3 people tend to do. The GTS are a bit more expensive than GT3 if I recall when I looked into it, but certainly cheaper than doing the whole liner.

Upper ducts are certainly for cooling. The radiators airflow, hot as it may be over ambient, is still well cooler than the rotor/hub area of a car on track.

alexb76

lol, you guys are too funny trying to wind tunnel this thing! The GT3 vanes are more directed to flow the air to the brakes better, but it's marginal vs. Carrera.

As Mike said, the real and noticable improvement is with GT2 ducts.

nwGTS

See that header up top that says 'technical discussion'? That's what we're doing here. Adding value and critical analysis to what otherwise would be a devolution into 6speedesque diatribe on taped splitters and stretched chrome three pieces. It might be arm chair in approach but this is an amateur blog and that's to be expected. At least I'm taking measurements and not just positing something is 'better' because it's bigger, smaller, wider, fill-in-the-blank.

I will never apologize for unbiased technical exploration. Furthermore, as a scientist, I'll happily bow to more thoroughly proven information over my own such as user AWay provided.

Not all of us have access to a race or tuning shops experience or equipment but some of us understand engineering principles and theories and beat try to pass on that information via technical analysis such as this one.

So, I sincerely hope it helped explain something new, something more thorough or both.

The mocking isn't helpful or appreciated here.