How does Dundon make a GT3 compete with the new 992 GT3RS?

The engine and gearbox are very similar between the GT3 and the GT3RS. The major differentiators for the RS are (in order) Aerodynamics and Suspension. We have detailed our suspension upgrade for the 992 GT3 in previous articles, and we are finally ready to share our full aerodynamic package. This package gives the standard GT3 a serious boost in downforce with the addition of our Valkyrie carbon swan neck wing, carbon dual dive planes, and a full carbon splitter.

Working in conjunction with Zebulon MSC (run by two IMSA/WEC race/performance engineers, the Neff brothers), we left no stone unturned. The overall goal of this development project was to create the best-performing options available for the Porsche 911.  An iterative design process was undertaken to determine these designs. Flow fields around the most popular “GT” versions of the 911 were simulated and analyzed in factory configurations to generate baseline data for each vehicle. Comparative benchmarks were derived through more CFD simulations of other solutions that parallel what is currently on the market. This baseline and benchmark analysis drives the direction of the development process. All simulations were run using a 100-mph free stream flow field and included full mesh adaptation and refinement. 

We know that every driver has different goals, so we approached the 992 GT3's aero upgrades in a multi-tiered approach. To start, we have the dual dive planes and gurney flap for the stock rear wing.

Front dive planes use the high-speed air flowing around the edges of the front bumper to create both a pressure differential across the component, as well as a vortex that travels down the side of the vehicle. These vortices are low pressure, therefore helping extract air from the front fender well while also helping control the air as it flows down the side of the vehicle. The flow field around the bumper is used to create a baseline design, which is then incrementally changed to meet the set expectations. It was found that different designs for each location (high & low) created the best results due to approaching flow field variance. This allowed for very efficient and effective downforce production.  

 The highlighted green is low pressure area created by the shape of the dive planes.

Gurney flaps operate through the modification of the flow field around an airfoil (i.e: the stock rear wing). Generally, these devices increase the magnitude of the pressure differential between the top and bottom of the airfoil (lift). They also help control boundary layer separation on the suction side of the airfoil, allowing a slightly higher angle of attack to be used. The height of the flap is defined by the boundary layer thickness at the trailing edge of the airfoil’s pressure side. While gurney flaps help increase downforce, they do increase drag as well. As such, a gurney flap is only recommended to enhance the stock wing’s performance but was not included in the new proprietary wing design.

The second stage upgrade pairs our dual dive planes with our Valkyrie swan neck wing. The Valkyrie wing is extremely efficient at low angles of attack (less than 4-5* typically), which means adding the dual dive planes provides enough grip to keep the car balanced. 

The rear wing element and endplate package was developed to work in harmony with the flow around the car and was benchmarked against several high-end wing options that are available. The airfoil profile is a bespoke anhedral 3D high L/D design that is extremely efficient at low to medium Angles of Attack (AoA) and will also produce significant downforce numbers at higher AoA with a gentle flow separation characteristic. The endplate design utilizes a specialized profile to reduce drag and is modified at every edge to reduce yaw separation, control upper and lower edge vortices, and increase the overall efficiency of the wing markedly compared to a normal flat endplate. 

The 992 GT3 does very well with the dive planes and upgraded rear wing. However, our goal was to really allow the GT3 to punch above it's weight. To help reach this goal, the team developed a very trick carbon front splitter. This piece is more akin to something you would see on an IMSA race car rather than a road going car.

The blue color shows low pressure zones, whereas the red areas are high pressure. The goal is more low pressure on the underside and more high pressure on the top.

Stock Porsches rely on a type of air dam or bumper lip to generate front aerodynamic loads. A true splitter uses smooth flow to generate a low-pressure zone from the high speed, free flowing air in front of and under the car. This leads some people to call these splitters “under wings”.  A well-designed splitter will also reduce drag compared to an air dam, adding to the car’s overall L/D (lift/drag) ratio.

One important feature of the Dundon splitter is more efficient when in roll and yaw (that is, it makes more downforce while the car is turning than it does in a straight line). This will help drivers make the most of the car at apex, shifting the Center of Pressure forward allowing drivers to load the front tires more where it really matters most.  Additional features like swappable end fences and replaceable rub blocks make the splitter highly functional for many situations, including top level competitive motorsport.

So now you know the background and ethos behind the creation of this package. Here's where the rubber meets the road:

The Complete Valkyrie Aero Package gives over 1500lbs of downforce at 160mph, almost 1000lbs more than a stock 992 GT3 at maximum settings. All this at mild settings of 90mm ride height and 5* wing angle. 

Absolute numbers are great, but the performance of the package at 80-120mph is really where it counts. This is generally the speed you are trying to turn the car and want your 911's aerodynamics to really help you.  

Our package really shines in this range, creating 885lbs of downforce at 120mph, 550lbs more than stock at maximum settings. That is where you will find the confidence to go faster and truly give the 992 GT3RS a run for it's money.