991.2 GT3RS Full Aero Package
What a wild year! With everything going on in the world over the course of 2020, we’ve been working hard here at Dundon Motorsports to get a bunch of new products off the line! Hopefully you’ve seen our 718 GT4 headers (<-- click here if you haven’t). We introduced the Swan Neck wing for the 991 GT3RS platform a couple weeks ago, now we are pleased to present the complete Aero Package from Dundon Motorsports. This kit combines the swan neck wing with a set of dual dive planes and a front splitter to balance the downforce across the front and rear of the car. We've been working on this kit for over a year, and are very excited to share it! Watch the video overview and continue reading below for more information on the Complete Aero Package.
When improving downforce on a platform, balance is critical. Too much downforce at the front and the rear will be all over the place. Too much at the rear and the front won’t grip. The package was developed using Computational Fluid Dynamics (verified in a wind tunnel) to achieve the right balance for the GT3RS.
We start with dual dive planes (sometimes called canards). Our dive planes come in gloss carbon fiber and accomplish a couple of things. First, they shift the aero balance forward. This serves to further balance the downforce generated by the wing, and improve front grip. The second thing the dive planes do is control and shape of the airflow over the car. With aerodynamics, disturbed or “dirty” air is the enemy.
The wheel and suspension assembly do a great job acting like an egg beater to the air flowing around and through them, creating a lot of dirty air. The dive planes serve to feed air up and over the front wheel, AND they create a vortex (like a tornado) on the outer edge of the front wheel. Dual dive planes like ours create a stronger vortex. These vortices create a low pressure area along the front wheel arch alongside the car to pull the turbulent air out of the wheel arch, further reducing lift and adding downforce.
The Carbon Splitter serves to bring even more downforce to the front axle to balance the big Swan Neck Wing. A splitter works to reduce lift at the front by separating and stalling some of the air on top of the splitter (standing on it if you will) and by speeding up the air under it thereby reducing the pressure, “lift” on the underside of the car. Since this is a street car we couldn’t have 6” of splitter sticking out front to use much of the “stand on it air”, so we chose to maximize the speeding up of the air under the front by making it smooth and including two large diffusers! The diffusers work to further speed up the air and facilitate an even greater decrease in pressure under the car.
The front lip of any track car is going to take a ton of abuse. For that reason, the splitter is constructed from a carbon fiber, and is completely reversible.
The swan neck rear wing generates a massive amount of downforce with only a small increase in drag. The majority of the downforce generated by a wing comes from the bottom surface of the wing element. The swan-neck mount leaves the under-side of the wing smooth and allows the air to pass over it relatively undisturbed. The element is adjustable from -1 degrees to 14 degrees angle of attack, allowing you to tailor the downforce to your experience, driving style and circuit design. When compared to a stock RS wing set at maximum attack (11*), the Swan neck wing at only 6* generates an additional 325lbs of downforce at 120mph. At 160mph the increased downforce is nearly 600lbs over stock!
One challenge we uncovered was with the factory engine cover hinges from Porsche. They are made of carbon fiber and designed to be lightweight, but when you increase the downward and rearward force on them to the degree that we have, they will fail. To combat this Dundon developed the “chassis lock”; a system that ensures that all forces are transferred directly to the chassis, not the decklid hinges.
With all of this added downforce (the kit adds an additional 900lbs of downforce at 160mph over stock) you will need to consider your suspension carefully to fully maximize the benefit of the kit. You can certainly add the wing and dive planes while running the wing at lower angles of attack and see great benefit, but if you’re planning to go full bore, and do the Dundon Complete Aero Package, then we recommend swapping out to our Motion Control Suspension 3-way damper kit. We have solutions for cars with and without aero and options to retain Front-Axle Lift for cars with Pneumatic and Hydraulic systems. At a minimum, consider upgrading your springs to ensure the front of the car doesn’t bottom out under braking.
As always, we try to have quantifiable results when building parts for a platform. For engine parts, we have dyno graphs. For this kit we have CFD data to prove the downforce, and we have graphs from track sessions. The graphs below are from two 991.2 GT3RS's that are identically equipped, with the only difference being the Ventus 3 aero kit with the wing at 9* (out of 14*). They were driven by the same pro driver in similar weather conditions and similar times of day, on the same Dunlop tires. This test took place at The Ridge Motorsports Park on ~60* days and these laps were run in the afternoon. Both cars feature our full D3 Power Kit, Motion Control 3-way suspension, and AP Radi-Cal brake kits.
The blue trace is with aero, red is without.
The first thing to note is the minimum corner speed on the aero-equipped car is noticeably higher. This speed transfers immediately to an exponential increase in speed on the subsequent straightaways (more to come on this in a future blog). The aero-equipped GT3RS also takes advantage of the extra grip at high speed by braking later than the non-aero car. Another important distinction is that the aero car doesn't appear to suffer from a drop in straight-line speed, as the drag increase for this kit is marginal.
The ultimate lap times for the two cars:
Ventus V3 Aero-Equipped 991.2 GT3RS: 1:44.98
Non-aero 991.2 GT3RS: 1:47.41
Anecdotally, our driver reported a marked increase in stability and confidence with the increased downforce. He shared that the aero made it "easy to drive the car fast", where the non-aero car required much more attention and felt "busier to manage." With additional downforce and a limited increase in drag, drivers of any experience level can benefit from the Ventus 3 kit when looking to improve lap times.
As we’ve said in the past, we do try to take a purposeful, holistic approach when developing a platform. When you start with an already capable machine like the 991.2 GT3RS, the car is so good you need to be careful and deliberate with everything you touch. We’ve curated our offerings to work in concert to do one thing: improve performance. That said, aero doesn’t make the car faster, the driver makes the car faster. Improved aerodynamics gives you options by making the performance envelope larger. The increased grip gives the driver the confidence to carry more speed, and therefore reduces lap times. We encourage a methodical approach when making changes of this magnitude. Work your way up to higher speeds and learn to adjust your approach with the increased traction.
When you’re ready to experience how easy it is to go fast on track, in the mountains or any favorite section of tarmac, give us a shout for a well engineered setup that keeps your car stuck and your smile wide.