Cancel

Porsche 911 50 Years

“By widening the front track we can support more rolling forces by the struts, and this allowed us to make the stabilizer a little bit thinner and not so stiff. Simultaneously this avoids understeering. So this new car is much more neutral than the 997. And with this new feature, the PDCC, Porsche Dynamic Chassis Control, it’s completely another world.” Weissach developed PDCC to limit body roll on its larger vehicles, the Cayenne and the Panamera. “I’m honest here,” Achleitner said, laughing, “we had several discussions: PDCC in a sports car? My God, are you serious? We are adapting Cayenne technology to our sports car? Can that be? “It makes a sports car completely different because it avoids any body roll. By avoiding rolling, we can keep the tire in its optimum position to transmit the maximum of forces to the road in every dimension. So this car is 14 seconds faster around the Nurburgring than the 997, but only four of those 14 come from PDCC. The rest is this longer wheelbase and wider track. It is 52 millimeters wider, so about one inch on each side. The structure takes up part of this number because we needed a little more space for the 20-inch wheels—the whole wheel, its diameter, its depth, to allow it full turning capacity.” The Carrera S rode on 20-inch tires, the Carrera on 19s. Those familiar with Porsche’s development process knew the engineers set goals or targets and they expect to encounter conflicts along the way. “The target and the conflict,” Achleitner continued. “One of these. Bigger wheels have a lot of disadvantages. They need more space; they are heavier. When we started the development, our chassis guys came to me and said, ‘We want to install twenty-inch wheels.’ And I said, ‘Well, okay, but first, go home and make a comparison between advantages and disadvantages. Because there are a lot of disadvantages.’ But finally, the number of advantages was bigger than the disadvantages because we can transmit more forces because of the bigger contact patch and we can reduce the tire pressure because the possible tire load is higher with these tires than it is for the smaller tires. This is another small step not only to make the car faster but to make it more comfortable.” Tire, road, and wind noise intruded into the 997 cabin, but it became an issue too late for Achleitner’s development engineers to fully address it at that time. It involved chassis and tire engineers, aerodynamicists and body designers, and the interior group. It was another target conflict that provided an unanticipated opportunity to heighten the driving experience for buyers. “It was not a target from the start,” Thomas Wasserbäch explained. He was general manager for 991 base engine development. “The new car is so much more quiet. Less tire noise, less wind noise. And by reducing these noises there was some space left in our ears for the engine noise we wanted to hear,” he said. That led to the Symposer, a joint development between Porsche and the Mann+Kummel Group in neighboring Ludwigsburg. Their multichamber module transferred acoustic pulses from the air intake through a funnel-like opening that housed a tuned membrane.
A new roofline adhered more closely to the 911 body shape as Michael Mauer’s exterior stylists worked to reduce the difference in appearance between closed and open cars. Convertible top engineers inserted a slim composite panel between cloth layers above the seats to better hold the roofline shape. Porsche Presse
A new roofline adhered more closely to the 911 body shape as Michael Mauer’s exterior stylists worked to reduce the difference in appearance between closed and open cars. Convertible top engineers inserted a slim composite panel between cloth layers above the seats to better hold the roofline shape. Porsche Presse
The Carrera S delivered 400 horsepower from its 3.8-liter engine while the base Carrera developed 350 from 3.4 liters. The Cabriolets began to reach customers in early 2013. Porsche Presse
The Carrera S delivered 400 horsepower from its 3.8-liter engine while the base Carrera developed 350 from 3.4 liters. The Cabriolets began to reach customers in early 2013. Porsche Presse “From there we ran a tube to the steel bulkhead at the rear of the passenger compartment,” Wasserbäch continued. “We developed a new exhaust system that merged the exhaust gas for all cylinders in a new manifold—in the past our Boxer engine sounded like two three-cylinder engines. The new system sounded like there are six cylinders, and we ran a tube from there as well. That steel bulkhead became the subwoofer for our exhaust system. And our sound is mechanical, not synthetic; outside the car you heard exhaust. Inside you heard intake and engine. The sound Symposer brought outside sound in. And incidentally, you could deactivate it if you wanted a quieter ride by pushing a switch on the console.” The 991 represented a fresh start with countless opportunities. With the 997, stylist Grant Larson sketched bigger tires onto his concept drawings and this sent chassis engineers back to their computers to redesign and strengthen rear structure and suspension to handle the additional stresses the larger tires introduced. The 991 emerged differently, and in the end only a few internal pieces of the direct fuel-injection type 9A1 Carrera and Carrera S engines survived the transfer process. “In the structure of the 997 we started with the 996,” August Achleitner said. “Of course we modified it, tire sizes, and so on, into the 997. But the structure basically was the same. Over time we had to reinforce it in several locations, sometimes just to make it suitable for all these crashes that were required. But then the car began to go away from its optimum. You can do it for one generation, maybe for a second one. Maybe. But then it’s over. “You have to throw it away and take a clean sheet of paper,” he went on. “Now you have to make a development for the next six or seven years, as long as you know the requirements for the structure.” Engineers understood there would be 21 variations of this car. Long-term requirements influenced the design and development of the controversial electronic steering. “We looked at every system out there,” Michael Schätzle explained. Schätzle was project manager for the complete 911 product line. “We didn’t like anything we drove. So we started from scratch. And that gave us the freedom to develop our own parameters, to address the way Porsche 911 drivers use their cars.” The new system employed a vehicle status sensor that constantly calculated forces impacting the steering rack-and-pinion from road and steering wheel inputs, such as steering angle and vehicle speed. The sensor interpreted these data and sent a calculation to an electric motor on the steering rack that applied appropriate steering torque by means of toothed belts and a recirculating ball. Steering feedback, crucial information about road surface and driving conditions, came to the driver through the steering wheel. The new 991 benefited profoundly from predevelopment. Dr. Heinz Soja arrived at Porsche in 1999 and helped establish the group that now tackles all things technical for any new vehicle. As each phase of vehicle development reached “freeze,” the moment at which specifications, designs, innovations, the appearance, the options, were set, the new ideas that each engineer and designer had devised went back into their desks to be retrieved when they started considering the successor. For Soja and his team of 70 engineers, these became the technical columns that defined the new car. “We looked intensely at our competition,” Soja said. “In this case, that even was our 997. And we asked ‘What are the mistakes in these cars?’” Porsche’s new motto, “Intelligent Performance,” was more than a catchy phrase. For the engineers at Weissach it was a guiding philosophy they used in reaching the primary target for any new 911: it must be faster than its predecessor. Every target seemed to come with a conflict. To be faster required more horsepower from a larger, heavier engine that used more fuel; better performance required a lighter-weight automobile, perhaps made from more expensive materials. STEERING ELECTRONICALLY Porsche engaged its longtime development driver Walter Röhrl repeatedly in developing the new car. It was Röhrl who posted the 991’s 7:40 Nurburgring lap time. Nowhere was his input more important than with its new E-steering system. “We spent five days developing the steering on the handling course at Nardo in southern Italy,” he said. “Then the engineers went back to Stuttgart and worked on parameters. One test we gave very much attention was driving in snow. Sometimes when you drive fast in snow you need to turn the wheel very rapidly to control the car and the system must keep up but not overcontrol it.” Holding an imaginary steering wheel in his hands, he snapped his arms to opposite lock. “They worked on that. Then we just spent three more days at Nurburgring. That was all it took to make it perfect. One thing the E-steering does is makes driving less fatiguing by filtering out minute road imperfections. “Our biggest challenge with this new system,” Achleitner recalled, returning to the question of long-term development, “was finding a motor that was small enough, light enough, and powerful enough to accommodate forces acting on the front wheels of the 991 GT3 RSR when it bumps the curbing at 200 kilometers an hour.”
As design director Michael Mauer admitted, the harder character line changed the 911. With that emphatic crease, it suddenly became acceptable to introduce subtle (always a watchword with 911 styling) edges in other places. Randy Leffingwell
As design director Michael Mauer admitted, the harder character line changed the 911. With that emphatic crease, it suddenly became acceptable to introduce subtle (always a watchword with 911 styling) edges in other places. Randy Leffingwell “One of our early questions,” Soja explained, “was to determine if aluminum was the lightestweight solution. We built an entire car in aluminum. And we learned it was not lighter and it was more costly. So we settled on the concept of a multimetal car. We had lots of ideas. We calculated and tried every one. The most important ones went to actual hardware. We tested our technical innovations on 997 mules. The skin, to save weight, was 45 percent aluminum. Structure came from a variety of high-strength steels, and where we integrated functions, we designed them so they met on die-cast magnesium. “We knew this car would be raced. Racers need a very stiff car to steer very exactly. But what also is important is extreme light weight. We talked with motorsports often. These considerations became part of our technical columns. They formed the car. The designers shaped the car around the technical columns.” The shape is one of the greatest challenges to creating a new 911. Somewhere in the world, dictionaries must illustrate the word icon with a silhouette of the 911. One definition of the word was “an important or enduring symbol.” “The roofline was inherited from all the 911s that came before,” Matthias Kulla said. Kulla was the general manager for exterior design at Porsche. “The only thing we could do,” he went on, “was to adapt it to the different proportions of the longer wheelbase. We tried to shift the weight point a little further back, not so far forward as the older ones. It started with the windscreen. It was an aerodynamic consideration to have a ‘faster’ windscreen. So we left the end where it was, but we pulled the foot of the windscreen forward 70 millimeters, nearly three inches. I think it was the roundest in the industry.” Working for design chief Michael Mauer, Kulla, and ten studios of designers, clay modelers, computer wizards, and studio engineers, had created the latest Cayenne, Panamera, Boxster, Cayman, the 918, and now the 991. Mauer challenged his entire staff, devising an internal competition for concepts for the new 911. “What happens at first, people have a lot of respect for the car,” Kulla explained. “They say, ‘Oh, it’s the 911. We shouldn’t change it.’” He recited the competition rules: “First, don’t be afraid. Be brave. Second thing, don’t exaggerate. Third, make it modern.” One of the car’s more distinctive new forms was its rear character line. “The back end character line appeared on a single sketch,” Kulla recalled. “And this was where I thought, okay there will be discussions.”
“The roofline is inherited from all the 991s that came before,” Matthias Kulla, exterior styling boss, explained. The longer wheelbase allowed stylists some creative options and a slight edge appeared in headlight lenses. Randy Leffingwell
“The roofline is inherited from all the 991s that came before,” Matthias Kulla, exterior styling boss, explained. The longer wheelbase allowed stylists some creative options and a slight edge appeared in headlight lenses. Randy Leffingwell
As typical with all-wheel-drive 911 models in the past, Weissach engineers widened rear track, by 1.65 inches in this new model, with rear fenders flared 0.87 of an inch beyond normal. The Porsche traction management system, PTM, maintained the balance between front- and rear-wheel drive, making decisions in 0.1 second. Porsche Archiv—Photo by Dieter Landenberger
As typical with all-wheel-drive 911 models in the past, Weissach engineers widened rear track, by 1.65 inches in this new model, with rear fenders flared 0.87 of an inch beyond normal. The Porsche traction management system, PTM, maintained the balance between front- and rear-wheel drive, making decisions in 0.1 second. Porsche Archiv—Photo by Dieter Landenberger “This was very controversial.” Michael Mauer explained recently. “Because it gave the car, how should I say it, a harder character?” Another line, an edge that stirred discussions, was the roofline that started at the A-pillar. It accentuated the roof, made it look longer, and finally it descended to the rear and formed an elegant sweeping crease around the new, smaller taillights. “We had gigantic tail lamps for what, 30 years?” Kulla asked. “So we decided to make them as small as possible, as low as possible. That was actually the reason for the reflector down low. If we had to include that function in this light, it would have made it 10, 15 millimeters taller. It was vertical once, actually. Which was interesting! “Every single surface inside every lamp was done in the studio, not by the engineers, and not by the suppliers. This is design work. Because they don’t know how to handle the surface contours like we do. So we gave them a set of data, they ran tests and the simulations, and they gave us feedback so we can correct our lines. And this took place 20, 30 times. “For the longest time we have had a really soft-sloping rear on the 911,” he continued. “You probably understand that there are not many areas where we can really make a big step. So it’s always in the subtleties.” There was that word again. “Those are the things that turn a nice car into a really good one. We worked very closely with the engineers and the toolmakers. All these little details made this by far the most precise 911 ever in terms of execution,” Kulla added. “I look at this car in beautiful light,” Mauer said, “and I think, ‘Oh, damn. It will be tough to improve on that one.’” What was the toughest improvement for Achleitner and his engineers to make advancing from 997 to 991? “For me, it was quite clear. It was the reduction of weight,” Achleitner admitted. To resolve the conflicts between efficient consumption and performance, he knew they had to reduce the weight. If not, they needed more horsepower, which was in conflict with the targets for consumption. From the start, he had his engineers calculating weights. This was done without the parts on the table but from designs still in a computer. Out of these efforts, they all concluded—no matter how many times they calculated the weight—that the car was heavier. “We did two or three workshops without the parts. And then again a workshop with the parts, the prototypes, and we made many comparisons. Even using motorcycle parts! In the end we found that our colleagues had some ‘reserves.’” At this, he began to laugh: “Everyone had some small ‘reserves.’ “And we put the first car on the weight station, the first car made from the pre-series where the parts are coming from the final tools. . . .” He laughed again. “The car was lighter than we calculated. This was a very, very happy moment. And this was without exotic materials. Only with aluminum. Steel. Some magnesium parts.” Lightweight parts filled the updated engines. These were all new for the 997 and substantially changed for the 991.
Depending on traction that the car’s electronics sensed, power shifted from 100 percent at the rear axle to all at the front. A new system, standard on C4s equipped with PDK, was adaptive cruise control, called Active Safe, which reacted to closing distances suggesting a collision. Porsche Archiv—Photo by Dieter Landenberger
Depending on traction that the car’s electronics sensed, power shifted from 100 percent at the rear axle to all at the front. A new system, standard on C4s equipped with PDK, was adaptive cruise control, called Active Safe, which reacted to closing distances suggesting a collision. Porsche Archiv—Photo by Dieter Landenberger “For the 997 these were the first developments,” Thomas Wasserbäch explained. Like his colleagues, he constantly developed ideas for the next-generation car. With them written down, when that project materializes, everyone knew exactly what they wanted to do. “We wanted to bring the engine speed of the GT cars to the serial production; it was our idea to lift the speed 300 rpm more. But to do that, you have to make it a little lighter in the drivetrain,” he said. “We learned it was better to make some mounted camshafts very exactly, to make the tribology, the interplay of friction and lubrication, better. So the friction goes down. That was another idea,” Wasserbäch added. “This would improve fuel economy and performance. “Our oil pump is a variable oil pump,” he continued. “We saw when we optimized the electronic application, the oil pressure was better; it improved on racetracks. So we retuned our system and we had lower oil pressure on the road when you drove on the highway in normal conditions. And when you went on the racetracks, the oil pressure came up.” Since they had forces of 1.3 or 1.4 G lateral acceleration with the 20-inch wheels, they had to provide a system for the engine to serve those needs as well. “It truly can be a car with two characters. It’s always a special engine for this car. Its optimums you see in the packaging. There is no free space! The engine is optimally configured for this car. “You always must have ideas because it never ends,” Wasserbäch said. “In the next generation you have to look for how you can increase performance again and drop fuel consumption and emissions more. So you need ideas. Our aim is that in the future, Porsche always has flat sixcylinder engines on the market. We know we have to hold onto the flat six.”
Previous Page Page 23 of 32 Next Page