acey81

My 991.2 runs a 991.1 GT3 very close. In fact, due to the drag that the 991.1 GT3 RS makes (especially if you added more wing), it is faster down a long straight. With upgraded brakes MPSC2 N1 tires, it is a very fast. However, to really compete it does need some downforce. Instead of sticking a big wing on it, I wonder if the 911R diffuser, (also used on the 991.2 GT3 Touring), might somehow work? I know that Suncoast states that it doesn't fit, but maybe the 991.2 GT3 version will? Or with some modifications? Any thought?

Will any of the 991.2 GT3 brake cooling work? The car needs bigger discs on tracks heavy on brakes, but the stock rotors could work with better cooling together with better pads and fluids.

Any other suggestions for brake cooling or downforce would be appreciated!

R_Rated

There is some brake cooling ducts as a part of the X51 kit - I'd start here and either look for these part numbers or get a diagram and build something similar.

With regards to GT3 spoiler - there is a risk with cooling since these cars are not turbo. BBI has an intercooler upgrade kit and there is also a Porsche OEM center radiator that would both help. I also recommend aquamist(made a thread with links but there was never any interest).

A SPASM lip is an easy path to front end downforce but the only way to get more on the rear is a wing.

Lastly - a diffuser could help on the rear. Vorsteiner has one that looks nice but there is no data to support and real increase in practical aero. A legit race shop may be able to help but most offerings are for nothing more than Aesthetics.

stout

I would have to think someone can adapt the .2 GT3 diffuser to a 991.2 Carrera. I'd stay away from aftermarket stuff for anything other than appearances—unless they have verifiable wind-tunnel data to back up their claims. Is your car an S? A base? Or? If no Sport PASM, next steps would include a Sport PASM front lip and the rear spoiler setup/settings from the Carrera T (which may be like or the same as the Cabriolet). A Gurney flap from the GT3 Touring would be my last consideration. Apparently, it is quite effective.

If you're on base brakes, I doubt cooling, pads, and fluid will be enough. They might be a good first step, but you likely need better/bigger rotors. Sounds like AP Racing may be working on a package.

spdracerut

My guess is the 911R diffuser would not be an easy bolt-on to the 991.2.

This article has pictures of putting the 991R diffuser on a 991.1 GT3RS:
http://www.motoiq.com/MagazineArticl...-Diffuser.aspx

Notice there are very specific mounting brackets which the diffuser attaches to which the 991.2 does not have. Plus, with the engines being different (oil pans, headers, etc), I think there's too much difference.

I

Valvefloat991

Even if it fits, the diffuser is likely too short to do much good aerodynamically. One of the primary reasons that Porsche switched the RSR to a mid-engine layout was to get the engine our of the way and make room for a large diffuser that could be far more effective. With the engine in the rear, no diffuser is likely to do much aerodynamically--even if it looks cool.

stout

The diffusors used on the 911R and 991.2 GT3/Touring are apparently effective—to the point that they were worth developing and implementing. It's telling that they took something they developed for the 911R and applied it to the new GT3...

Valvefloat991

I'm not saying that the 911R diffuser doesn't do anything, but here's a diffuser that works:

spdracerut

I got a couple pics of the diffuser (among other things) on 911 RSR from the 2016 LA Auto Show. That diffuser has a lot of length and height to it.
http://www.motoiq.com/MagazineArticl...e-911-RSR.aspx

evilfij

acey81

Interesting, that would be a quite simple solution. I am planning on lowering the car with new springs, which should help the front "splitter" to be a little more effective. Does anyone know if the Porsche Turbo S aerokit fits on the 991.2 GTS? Same body, no?

Seems like the R / GT3 T diffuser is a no.

Regarding the additional brake cooling from the X51-pack is already mounted on the GTS, since it has the extra power?