How Performance Testing is Conducted at the Nürburgring Nordschleife

You might have heard about an urban legend that some driving virtuosos are skilled at perfectly turning a corner. They probably know their line should have a smooth, spiral shape from the edge of the track to the apex. One more thing that I clearly know is that these specialists always and seriously consider some testing aspects. Which test will they take to find out what they think is important to make their cars faster and handle more precisely? Before I talk about these technical terms, let me start with some background on what has been happening here.

The Nürburgring Nordschleife has been one of the primary testing grounds. The track's layout keeps drivers on the edge of their seats. It is incredibly difficult to conquer, making it a nail-biting experience. However, this tricky road helps many people fine-tune aspects like handling, aerodynamics, and durability. The reason why it's an ideal location for some tests is because of the track's unique characteristics that help push the limits of performance and engineering. The Nordschleife stretches 20.8 kilometers (12.9 miles) and includes over 150 corners, from tight hairpins to fast sweepers and more. The track has major elevation changes, with about 300 meters (984 feet) of difference, making it a tough challenge for many drivers. The track surface has different types of asphalt that can significantly affect grip levels. Weather conditions in the Eifel Mountains can change rapidly. That's why people suddenly face track conditions that keep changing, even within a single lap.

Handling

What is widely known is the Nordschleife’s high-speed corners, tight bends, and elevation changes. Engineers use them to test a car’s handling characteristics under extreme conditions. They also assess how the car behaves in different types of corners and how it responds to steering inputs at various speeds.

In high-speed corners, keeping cars steady in the air is super important. To make sure a car remains stable and predictable at high speeds, engineers monitor its aerodynamic performance through corners like Schwedenkreuz, assessing downforce, drag, and airflow over the car's body and checking some stability and grip. Talking about which data to collect, what helps analyze the car's behavior is the high-speed telemetry data, including speed, lateral G-forces, and aerodynamic pressure sensors. To evaluate the car’s responsiveness and precision when making quick steering inputs at high speeds, Engineers use sections like the high-speed sweepers (race tracks where drivers have to maintain high speeds while passing through gentle to moderately sharp curves) in Kesselchen. Here, they test how the car responds to fast steering inputs and transitions. From this repetitive process, they can refine the steering ratio and power steering assistance levels.

Also, steering angle sensors and yaw rate sensors are crucial for understanding the car’s handling dynamics. Steering Angle Sensors measure the angle of the steering wheel. It provides data on the driver’s input and the direction in which the car is being steered. Yaw Rate Sensors measure the rate at which the car is rotating around its vertical axis. It's good for detecting oversteer or understeer conditions and assessing the stability and control of the vehicle. There might be some parts that these sensors can't detect. Then, we need driver feedback to check some issues.

In Tight Bends, engineers utilize corners like the Karussell, where the car’s suspension, chassis balance, and weight distribution are thoroughly tested so that the car can handle sharp turns without losing grip or stability and achieve a balance between understeer and oversteer in tight, low-speed corners. Data from suspension travel sensors, tire slip angle sensors, and load sensors can help engineers adjust suspension settings and weight distribution.

It will be no use if they don't test a car’s braking efficiency and stability under heavy braking conditions. Tight bends that need heavy braking, such as Aremberg corner, are used to assess brake fade, pedal feel, and ABS (Anti-lock Braking System) performance. Brake fade is the reduction in stopping power after repeated or sustained brake use, especially in high load or high-speed conditions. When this happens, stopping distances increase, the car becomes harder to control, components overheat, and drivers become fatigued. They also use brake temperature sensors, brake pressure sensors, and deceleration rates to evaluate and improve braking systems.

For the suspension system to deal with sudden changes in elevation without compromising comfort or control, sections like Fuchsröhre, steep downhill sections followed by compressions, can be used to test the suspension’s ability to maintain tire contact and absorb shocks. Suspension travel data, damper velocity sensors, and accelerometers give some valuable insights into how the suspension responds to elevation changes. To evaluate the car’s power delivery and traction control systems on varying gradients, they utilize Uphill sections like the climb after Bergwerk to test the engine’s power delivery and the effectiveness of traction control systems in maintaining grip. They put a continuous load on the engine, requiring it to produce consistent power to overcome gravity. So the transmission must effectively transfer power from the engine to the wheels without significant losses, especially on steep inclines. We might encounter traction conditions like wet, dry, or mixed surfaces from which they can test the effectiveness of the traction control system in preventing wheel spin and maintaining optimal grip. Engine performance data, traction control system feedback, and wheel slip sensors are also analyzed to optimize power delivery and traction.

Aerodynamics

High-speed sections like Döttinger Höhe allow for testing aerodynamic efficiency and stability at high velocities. Downforce levels can be fine-tuned to ensure the car remains stable and controllable, even at top speeds. To evaluate and optimize the car’s aerodynamic properties, reducing drag while maximizing downforce, cars are driven at high speeds along Döttinger Höhe, with engineers measuring aerodynamic drag and lift forces. Computational Fluid Dynamics (CFD) simulations are often validated with real-world data from this section. Based on the specific data, they adjust some components like spoilers, diffusers, and canards to enhance aerodynamic efficiency.

Cars are loaded with all kinds of digital sensors and data-logging equipment to measure key stuff like aerodynamic drag, lift, downforce, yaw, pitch, and roll. These sensors include things like pitot tubes, pressure sensors, and load cells. Engineers first gather baseline data without tweaking anything to set a reference point.

During high-speed runs, they push the car to its limits on the Döttinger Höhe straight, one of the longest and fastest parts of the Nürburgring Nordschleife. Drivers keep the pedal to the metal to simulate some real-world high-speed conditions. While doing this, they collect real-time data on aerodynamic forces (drag and lift), vehicle stability (side winds, pitch, and yaw), and other dynamic responses. High-speed cameras and telemetry systems record everything about the car’s behavior.

Then come the Computational Fluid Dynamics (CFD) simulations. Engineers use these simulations to model airflow around the car and predict aerodynamic forces. They can help them spot potential issues and areas for improvement. The real-world data from the high-speed runs is used to validate and fine-tune the CFD models so that the simulations match up with real-world conditions.

Engineers then check the collected data again to spot any aerodynamic inefficiencies or stability issues. They analyze drag coefficients, downforce levels, and the car's dynamic responses. They show some specific areas where aerodynamic performance can be improved. For instance, common focus areas are excessive drag at high speeds, insufficient downforce, or instability due to lift.

Adjusting the angle of attack, size, and shape of the rear and front spoilers can significantly affect downforce and drag. It's because these changes alter how air flows over and under the car, which impacts its aerodynamic efficiency and stability. Engineers may change spoiler settings to get the balance they hope for between downforce and drag and improve the car's stability and performance at high speeds. A rear diffuser manages the airflow under the car to create downforce. For example, the Ferrari 488 GTB has a slick rear diffuser that speeds up the air flowing underneath, which cuts pressure and boosts downforce. This makes the car grip the road better, especially at high speeds. Tweaking the diffuser’s angle and shape can boost its effectiveness by improving airflow under the car, cutting turbulence, and upping downforce.

Canards are small aerodynamic surfaces placed on the front bumper. They are small aerodynamic surfaces on the front bumper that can be adjusted to improve front-end downforce and reduce lift. Smoothing the underbody and adding venturi tunnels can also reduce drag and increase downforce. After making these changes, the car goes through another series of high-speed runs on Döttinger Höhe. Engineers keep tweaking and testing until they achieve optimal aerodynamic performance, using the new data to make further adjustments.

Make it more durable and reliable.

As I said before, the track puts significant stress on all vehicle components, from the engine and transmission to the brakes and suspension. Continuous laps at high speeds help identify any potential weaknesses or failure points. From this, they can figure out how the car can withstand prolonged stress and high-performance driving. Models like the 911 also undergo rigorous testing here to meet high performance and reliability standards.

They get some feedback from each other.

Professional drivers and engineers work together during testing sessions. They provide continuous feedback to improve the car’s performance and handling. Each driver offers their take on how the car behaves, noting things like steering response, stability, braking performance, and overall handling. They point out where the car feels unstable or unresponsive, whether it's understeer, oversteer, brake fade, or aerodynamic issues.

Engineers then look at the feedback to figure out where the car’s performance is falling short. They use advanced software and simulations to make sense of it all and come up with some solutions. Regular debriefing sessions with the drivers let everyone discuss the data and share their experiences. They sort out the issues by how much they affect performance and safety and decide on what to tackle next.

To improve handling and stability, engineers might adjust spring rates, damping settings, and anti-roll bar stiffness. They also fine-tune throttle response, gear ratios, and traction control settings based on feedback. Then, they take the car back to the track for another series of high-speed runs to keep the testing conditions consistent. Telemetry data is continuously monitored, and drivers provide real-time feedback on the changes. Based on this new data and feedback, they make further tweaks to aerodynamic elements, suspension settings, or engine calibration. Each round of changes is validated through multiple test runs to ensure they achieve the desired effect.

Benchmarking and Lap Records

The Nürburgring lap times are often used as benchmarks for performance. Achieving a fast lap time shows off a car’s capabilities and engineering excellence. Porsche, for example, frequently uses these benchmarks to measure their models against competitors and previous versions.

Porsche has set multiple lap records at the Nürburgring. The Porsche 911 GT2 RS holds the record for the fastest lap by a production car, completing the circuit in just 6 minutes and 47.3 seconds in 2017. The Porsche 918 Spyder, a hybrid supercar, also set a record in 2013 with a lap time of 6 minutes and 57 seconds.

Finalizing my article

Testing at the Nürburgring Nordschleife is more than just a series of laps around a challenging track; it requires close cooperation between drivers and engineers to push both cars and drivers to their limits. Even though continuous feedback loops can be frustrating, they never stop working because they know the satisfaction that comes when every aspect of a vehicle's performance is optimized. With their hard effort, cars are perfectly tuned to get what they want. So next time you see a car boasting about its Nürburgring credentials, you’ll know the dedication and expertise that went into earning that badge of honor.