Porsche and BMW M3/M4 on the Nordschleife
A look back at 24 years of development
Why is there no Supertest in this issue? It’s not my fault, because one of the hottest supertests of the 2021 season is lying dormant on my hard drive. Last September, I drove the Porsche 992 GT3 around the Nordschleife – but we can’t publish the supertest until April. No amount of begging and pleading with the GT fathers Walliser and Preuninger helped-it’s the Porsche press department that has the final say.
And now? Using the faithful Supertest companions BMW M3/M4 and Porsche 911 GT3 as examples, we analyze the fascinating development of Nordschleife lap times from the beginning of the Supertest to the present day.
Who better to explain this subject than the makers behind the automotive Ring heroes? We therefore welcome Dirk Häcker (Head of Development BMW M GmbH) and Jörg Weidinger (Test Engineer in the chassis test BMW M GmbH) as well as – last, but not least – Andy Preuninger (Model Series Manager GT vehicles Porsche) to a small but very competent round of talks.
First super test in issue 3/1997
In 1997, the M3 E36 with SMG and 321 hp took part in the first super test. Lap time at that time: 8.35 min.
We’ll let our M colleagues from Garching go first. After all, it was the M3 E36 that took part in the first super test in sport auto 3/1997. Nordschleife in 8.35 minutes. At 7.37 minutes, the F82 GTS circled the Ring in the 9/2016 Supertest as the fastest representative of the M3/M4 range to date, almost a minute faster.
What factors have had the greatest influence on Nordschleife lap times in M3/M4 development over the years? Dirk Häcker: “Key levers are the optimization of wheel loads – both stationary and dynamic – and maximum potential for power transmission. The wheel loads on the M3 are always based on the base vehicle, so we are fixed in the wheelbase compared with the base model. But what we have always looked at very intensively in recent years was: with what maximum track widths can we still find ourselves in the various M3/M4 generations, or what is still feasible to generate a larger tuning or downforce basis with adjustments to body perimeters in the basic concept?”
Another important point was the further development of damper technology. Dirk Häcker: “We started out with conventional dampers, which of course have also evolved, but have now switched to adjustable damper systems in the last few generations. We are currently using a system that is not only found in the M3 and M4, but also in other vehicles. With this system, we have taken an extremely big step forward, especially in the context of dynamic wheel load changes. The system now manages this trade-off between wheel and body damping in a very balanced way, which in this context naturally pays off in terms of minimizing wheel load fluctuations and good wheel loads.”
Aerodynamics is an enduring theme. The fastest representative of the M3/M4 range to date, the M4 F82 GTS, generates 52 kilograms of total downforce at 200 km/h.
While an M3 E36 recorded 40 kilos of lift at 200 km/h on the rear axle alone (in the early years of the Super Test, aero values were only determined on the rear axle), the M4 F82 GTS generated 52 kilos of downforce on both axles combined. Dirk Häcker: “The subject of aerodynamics is interesting because you also have wheel load changes due to driving speed. Even though we usually didn’t use extreme aids in aerodynamics in the M3/M4 generations, we naturally made sure we achieved a harmonious balance in this interaction as well. In this respect, the downforce coefficients at the front compared to the rear are extremely important factors that also help in wheel load considerations.”
Häcker continues: “If we now have the wheel loads on the road in principle, then the question is: How do we get the power transmission right in the longitudinal and lateral directions? Of course, tire dimensions also play an important role here. Of course, tire technology has also evolved – in the 35 years since the M3 was launched. It is also important to have axle kinematics and elastokinematics that are adapted to the wheels/tires. What has proven to be a very effective tool in recent years is the question: how do you specifically – stiff where it’s needed, not stiff where it’s not needed – tie the chassis to the body? On this point, the cars have made significant gains in performance over the last few generations.”
For all its cult character, an M3 E36 accordingly feels soft compared to a modern M3/M4 generation. Says Jörg Weidinger: “You feel at least 100 percent stiffer than in the E36. That doesn’t just come from the current chassis components; it also comes from the tires. Tire stiffnesses had to go up because tire designs got better. The tire designs got better because we wanted to make the grip better. Of course, the body stiffness also went up, because no stiff chassis helps if the power transfer fizzles out in the body.”
M3 CSL: God, legend, hero
“Linear handling that is reproducible and predictable right up to the limit – that’s our philosophy,” Dirk Häcker, Head of Development BMW M GmbH, Jörg Weidinger, Test Engineer in the BMW M GmbH chassis test department (pictured right).
Why a standard M3 E36 today would certainly not only give pleasure at the limit on the Nordschleife? The subject of brake technology. Dirk Häcker: “There has been a great deal of development in the last few generations – not only in brake dimensions, but also in ABS performance in particular. Especially in the E36 times, when ABS systems hadn’t been around that long either, the ABS reached its limits on bumps or crests.”
Since the beginning of the Super Test, drivability has been the most elementary key to a fast Nordschleife lap time. Dirk Häcker: “Driving precision and accuracy as linear, neutral handling that is reproducible and predictable right up to the limit – that’s a very important philosophy for us. We also want drivers who don’t drive as much as we do to feel comfortable in the car after a short time and then relatively quickly reach the limits of what is finally feasible with the car. If a test driver who is not so familiar with the car can get within four to five seconds within a few laps, then we’ve almost achieved more with that than with the absolute lap time.”
Jörg Weidinger: “The M3 CSL was the point where it simply became clear that driving performance is one thing, but drivability is another. That has become an insanely important point in the meantime: How can you generate a lot of power, and how do you get that feeling of confidence in the car at the same time?”
The idolized M3: At 1,421 kilograms, the CSL will probably forever remain the lightest M3 in the super test.
Speaking of the M3 E46 CSL. God, legend, hero – to this day, the über-M3 from 2003 is rightly idolized. For BMW M, it was also the starting signal for a new era. Dirk Häcker: “The E36 M3 was of course also intensively tested on the Nordschleife, but lap times on the Nordschleife only really came into focus with the E46 CSL. With aero, lightweight construction and Cup tires – the first time an M3 had Cup tires – the M3 CSL naturally had the task of showing what it could do compared to the base model. Today, we now also simulate lap times on the Nordschleife using a corresponding tool.”
Looking back at the CSL, however, always puts a finger in a wound. At 1,421 kilograms, it will probably forever remain the lightest M3 in the super test. Dirk Häcker’s honest answer on the subject of weight: “It’s true that the cars have not only become bigger, but also heavier due to increased dimensions, additional technologies and new emission requirements. That’s the way it is – we can’t argue against it at this point either.”
Even though the weight increase annoys us sports drivers and is becoming an issue again with the current M3/M4 generation G80/G82, the M makers are wrestling with the kilos. Jörg Weidinger: “I can say one thing from the horse’s mouth: I don’t know anyone like Dirk who is so extremely concerned about weight. I’m just going to blurt that out now, because I know how precisely he has every kilo explained to him – whether it’s cars that are still in the future or cars that are already out now. We’re both weight fetishists – but in most cases, our hands are tied.”
45 seconds separate the 996.1 GT3 and the 991.2 GT3 on the Nordschleife – a time advantage that is not only due to the extra 140 hp.
Now it’s time to look at a weight fetishist who likes to fight in the gram range – welcome again, Andy Preuninger. But the Porsche 911 GT3 has also seen its weight spiral upward from the 996.1 to the 991.2. In addition to the aforementioned thumbscrews due to legal requirements, the 911 in general and the GT3 in particular have also undergone a growth in size.
In Flacht, however, they are fighting doggedly against the kilos – with a respectable success. The sensational news: The 992 GT3 test car, which will hopefully soon go through the super test, weighs 1,483 kilos less (!) than its 1,492-kilo 991.2 predecessor. Andy Preuninger: “Weight plays a big role at the Ring. The many fast changes of direction reward low inertias and protect tires and brakes. Especially over longer distances, not just for the one fast lap. That has to go all day and on the following ones as well. No wonder most ‘Ringtaxis’ are now GT cars.”
45 seconds separate the 996.1 GT3 and the 991.2 GT3 on the Nordschleife – a time advantage that is not only due to the extra 140 hp between the two generations, but to numerous factors. Andy Preuninger: “It was definitely improvements in many small to medium steps with contributors from the entire vehicle, be it powertrain, chassis or bodywork, i.e. aero. Leap-fixed variables, of course, are already the tires. Great progress has been made here, especially in the last ten years. The first UHP tires, in the GT3 from the 997 Gen I onward, were already a gamechanger in dry performance. Of course, the now excellent control system quality also makes a massive contribution. Features such as PDK with shift times like in Formula 1 and intelligent differential lock or rear-axle steering are components that make the car faster and add to the drivability account.”
“It’s really intense what the cars can do today. A few years ago, that was reserved for slick racing cars,” says Andreas Preuninger, model series manager for Porsche GT vehicles.
The subject of drivability enjoys a particularly high priority in GT3 development. Andy Preuninger: “If the car doesn’t make it easy and controllable to call up the performance, you can’t call up the potential without having ‘wet hands’ all the time. And then the fun quickly falls by the wayside. For us, achieving the perfect balance is more important than anything else. Driving fast on a circuit is a bit like ballet; everything has to be perfectly synchronized and give the driver clear feedback. The harmonious interaction of the front and rear axles plays a very big role here.”
Preuninger goes on to explain, “The rear axle must react just as quickly as the front axle to steering inputs from the driver. A phase delay must be absolutely avoided. That brings unrest into the car and slows down the driver’s confidence. The spring/damper setup must also be right – hard doesn’t necessarily mean fast. Above all, the damper must react quickly so that the car can iron away bumps as ‘smoothly’ as possible and the excitation is not transmitted to the body.”
996 GT3: Walter plus Stoppuhr
“Walter fixed his old stopwatch to the steering wheel with Velcro and hit the track in 7.56 min at the first go. The time was so incredible for a car with a license plate back then.”
In the younger GT3 series, the lap time improvements are significantly greater than in the early generations. Andy Preuninger: “With the 991, a number of things came on board almost simultaneously that moved the car forward significantly. PDK, variable diff, rear-axle steering, wider track, more wheelbase, aero, more extreme tires.”
At the same time, factory lap times came to the forefront specifically in the last decade. Preuninger: “The communicative focus on the Ring and the times that can be achieved there has increased significantly. In the past, we were almost alone there and mentioned the lap time in passing. That made sense, since the Ring has always been one of our main test tracks. In the case of the 996 Gen I, the communication of the Nordschleife time actually came about rather by chance. Roland Kussmaul, the technical director of the ‘original GT3’ at the time, asked Walter Röhrl to support him during the evaluation and acceptance tests, and Röhrl didn’t have to be asked twice. He fixed his old stopwatch to the steering wheel with Velcro and immediately clocked 7.56 minutes. The time was so incredible for a car with a license plate back then.”
Preuninger: “There was no serious competition. Then the M3 CSL came along and rushed around the Ring in just 7.50 min. A drumbeat that kept us busy. For me, this supertest was the start of the burgeoning interest and the works wrestling for the prestigious fastest lap. Fortunately, we had developed the first GT3 RS to market maturity almost in parallel with the M3 CSL. In the 997 generation, we then had the fast Nordschleife lap in mind right from the start of the project. The super test was established and has since been highly regarded by experts and customers alike. It’s no wonder that the 997 GT3 I only started with UHP tires as standard and that the tuning laps on the Ring increased quite significantly. We also wanted to match or even top the time of the 996 RS with the new ‘normal’ GT3, that was the declared goal. If you look closely at the history of GT cars, you’ll see that this strategy is still being lived out successfully today.”