Next Generation Porsche 911 Cabriolet - In Detail

Press Release

Porsche Active Suspension Management

Standard on the 2005 Porsche Carrera S Cabriolet and optional on the 2005 Porsche Carrera Cabriolet is the new Porsche Active Suspension Management System (PASM), which uses active damping technology to provide two suspension systems in one – one designed for an athletic yet comfortable ride, the other for performance driving situations.

By pressing a button on the center console, the driver can switch from PASM “Normal� to PASM “Sport.� Even in normal mode, the PASM suspension lowers the car by 0.39 inches (10 mm) compared to the standard 911 Carrera suspension setup. When switched into its sport setting, PASM activates a firmer damper control map to provide extreme agility and dynamic control that minimizes body roll.

There are advantages to PASM even when left in its normal setting because it automatically adjusts to changes in driving style, gradually becoming firmer to respond to greater dynamic forces.

The PASM system combines continuously adjustable shock absorbers, a pair of accelerometers – one in the front right damper dome, the other in the left rear – that determine vertical movements of the car’s body and an electronic control unit that also has access to steering angle, road speed, brake pressure and engine torque figures and thus can provide optimum damper control for each wheel through the active dampers that have a similar structure as standard shocks, providing damping with oil pressure, but that also have a bypass valve that opens and closes to increase or reduce the oil flow as needed. (Should the system fail, the bypass valve automatically closes, putting PASM into its hardest position to assure the safety dynamic driving mode.)

Settings for any driving situation

PASM is equipped with five special software modules – lane change, vertical control, lateral acceleration, brake and load change – to provide optimum settings for any driving condition: Lane change module: In response to rapid movements of the steering wheel in a sudden maneuver, the system instantaneously increases damper forces on both axles, reducing any tendency toward sway or rocking.

Vertical control module: In the normal program, damper forces increase whenever vertical movement of the car’s body exceed a threshold, for example, when driving on a bumpy surface. This prevents any risk of the body starting to rock. However, when in the sport program, the system reduces the damping effect to maintain wheel contact with a rough surface, preventing the risk of the car “jumping� around. Lateral acceleration module: In the normal program, damping varies through a curve, adjust with road speed and lateral acceleration.

Brake module: As soon as the driver applies the brakes, PASM firms damping to reduce body dive, ensuring faster transmission of brake forces to the road. Then, at a certain point in the braking process, the system switches to softer damping, with different forces applied in the front and rear of the car. This ensures better surface contact and shortens stopping distances, even on rough roads.

Load change module: In all-out acceleration, with the driver lifting off the accelerator while shifting gears, the control maps are adjusted for the front and rear axles. In the normal mode, harder damping is used briefly to prevent too much squat. In the sports mode, a softer damper response is used to improve traction, for example, on a rough road surface.

No spare tire

Because of improved tire technology, and to reduce the weight of a spare, jack and tools (some 22 pounds or 10 kg.), the 2005 Porsche 911 Carrera Cabriolet and 2005 Porsche 911 Carrera S Cabriolet dispense with those accessories and replace them with tire sealant and an electrical air compressor, allowing emergency repair of a small puncture and the ability to drive at speeds of up to 50 mph (80 km/h) without damaging the wheel.

Optional for the first time on both cabriolets is a tire pressure control (TPC) system that monitors the pressure within each tire as well as tire temperatures and warns the driver through a signal on the instrument cluster if there is inadequate pressure or a gradual or sudden lost of pressure.

Reinforced brakes on Carrera S

The 2005 Porsche 911 Carrera Cabriolet and the 2005 Porsche 911 Carrera S Cabriolet stop with the sort of braking authority that characterizes the dynamics of all Porsche vehicles. The 911 Carrera Cabriolet has 12.53-inch (318 m) front rotors and 11.77-inch (299 mm) rear rotors, all cross-drilled and inner-vented with black-colored, monoblock, four-piston calipers. Compared to the former model, the brake servo has been increased by 17 percent to 4.5:1, reducing the force needed on the pedal and providing more spontaneous braking response. Braking cooling also improves for 2005, thanks to the new front axle pivot mounts and enhanced under-vehicle airflow.

The 2005 Porsche 911 Carrera S Cabriolet has even larger brakes: reinforced four-piston monoblock red-painted fixed calipers front and rear with 12.99-inch (330 mm) front and rear discs and larger brake pads.

Porsche Ceramic Composite Brakes

Porsche Ceramic Composite Brakes are available on the Cabriolets. Instead of metal, the 13.78-inch (350 mm) brake discs are a ceramic material that provides high and consistent levels of friction during application. They also weight approximately 50 percent less than metal discs and thus reduce unsprung masses, by 34.4 pounds (15.6 kg).

For 2005, the Porsche Ceramic Composite Brakes are more rigid, yet include more interior cooling ducts. Fiber reinforcement on the friction surface is increased, significantly enhancing resistance to abrasion under high loads.

New variable-ratio steering

For the first time, the 911 Cabriolet now comes with standard variable-ratio steering that enhances the car’s agility on winding roads while retaining exceptional stability at higher speeds. When the steering wheel is turned with 30 degrees of its centered position, the steering ratio remains similar to that on the previous generation 911. This assures a smooth and calm driving experience, even on rough surfaces on which a driver might have a tendency to steer too much.

However, when the steering wheel angle exceeds 15 degrees from center in either direction, the steering ratio becomes more direct, reducing the lock-to-lock ratio from its usual 2.98 to only 2.62. This gives the driver better control both on fast, winding roads and in slow-speed parking maneuvers.

In addition to the new variable ratio technology, the Cabriolets have steering columns that both tilt and telescope to better fit each driver. The wheel can be adjusted by 1.57 inches (40 mm) both in height and reach. The steering system also includes a new electric steering wheel lock integrated into the car’s anti-theft immobilizer system.

Improved aerodynamics

The Cabriolets’ design evolution features a new, oval-shaped headlamp set into an arching front fender with separate turn indicator and fog lamps set horizontally into the curving edges of the front bumper above redesigned air inlets.

Smoothing the surfaces and enhancing the design of transitional areas beneath the front of the cars to create a low-pressure area that increases downforces on the front axle also help grip. The section radii of the front end and wheel wells also controls airflow to reduce lift. Special air ducts on the vehicle’s new, longer and smoother under-floor cover helps to direct cooling flow to the brake discs, transmission and differential. The cover itself significantly reduces air resistance and lift.

Wheel spoilers are used to reduce drag by guiding air around the wheels. Optimized brake air spoilers and pivot bearings ensure effective air around the discs, reducing brake disc temperatures by some 10 percent.

The new design also includes new double-arm rearview mirrors. The mirrors, similar in design to those on the Porsche Carrera GT supercar, guide air along the side of the car toward the rear spoiler, thus reducing turbulence that might otherwise result in wind noise inside the vehicle’s cabin. At the same time, the design of the mirrors helps to keep dirt and moisture off the side windows. The mirror casing and double-arm design increases downforce on the front axle and, by channeling air toward the rear spoiler, increases positive forces on the rear axle as well.

The flow of air used to provide engine cooling improves by some 20 percent. Air leaving the front radiator flows sideways into the wheel arch rather than downward in front of the wheels. This reduces losses in the airflow ducts and minimizes lift effects on the front axle.

Special ram-air flaps around the engine fan also boost cooling airflow without having to enlarge the air scoop openings. At low speeds, the flaps remain closed and air is drawn only through the heat exchanger, but at around 45 mph (70 km./h), the flaps open under ram pressure and provide enhanced cooling.

Taut, tones styling cues

From a side view, fenders are more muscular and wheel arches are more accentuated and doors are inset with more pronounced lower sills. Improved sealing allows a slimmer cross-section for windshield, side and rear window elements and enhances the overall appearance of the greenhouse detailing.

The rear view of the car features flared wheel wells and wide, brilliantly lit, red and silver tail lamps on either side of the engine cover. Distinctive air scoops built into the rear spoiler and higher mounting of the third brake light emphasize the enhanced power of the rear-mounted boxer engines.

Tail pipes are distinctive

To distinguish the 2005 911 Carrera Cabriolet and the 2005 911 Carrera S Cabriolet from behind, the S model has twin round tailpipes on either side while the Carrera has a pair of oval-shaped exhaust pipes.

The tail pipes are part of an all-new exhaust and catalyst system designed to make the convertibles even cleaner in their exhaust emissions. The Carrera S Cabriolet is equipped with an exhaust manifold with much shorter individual pipes designed to lower cold-start emissions from the more powerful engine. Both cars use the same two-stage “cascade� style catalyst designed to reach operating temperature more quickly and efficiently.

The new exhaust system makes the cars some 15 percent cleaner than on previous models.

More powerful 3.6-liter engine

While the 3.6-liter engine in the 2005 Porsche 911 Carrera Cabriolet is familiar, fine-tuning, especially of the air filter, has increased output by five horsepower. Torque remains at 273 pound-feet (370 Newton meters) at 4,250 rpm.

Crucial to the engine’s performance is Porsche’s patented VarioCam® Plus valve management technology that combines camshaft control on the intake side with variable valve lift. VarioCam Plus adjusts camshaft position to provide continuously adjustable valve timing and also incorporates two camshaft profiles and two sets of tappets to vary valve lift and duration. This system helps to both “fatten� and smooth the torque curve while reducing emissions. To provide optimum oil flow through the alloy engine block and cylinder heads, Porsche uses integrated dry sump lubrication and three oil pumps – one in the crankcase and additional pumps within each cylinder head, thus assuring proper lubrication despite the forces of hard acceleration, braking or cornering.

For 2005, the oil pump on the 4-5-6 cylinder head is combined with a pneumatic vane-cell pump to provide necessary vacuum for the brake servo as well as the engine and transmission control systems. This technology greatly reduces hydrocarbon emissions following a cold start and engine warm-up.

3.8-liter engine for Carrera S

To create the more powerful 3.8-liter engine that provides 355 horsepower for the 2005 Porsche 911 Carrera S Cabriolet, engineers did more than simply increase the bore diameter by 0.12 inches (three mm). They also changed the intake manifold and modified the intake camshaft lift pattern. Injector angles have been changed, assuring that more fuel goes to the center of the combustion chamber in the intake stroke. This means an even better fuel/air mixture, reduces exhaust emissions (even after a cold start) and produces more torque than the 3.6-liter throughout the power curve.

The entire intake system was redesigned and provides smoother flow with less resistance.

A Helmholtz resonator is used to refine acoustics. This provides more than 18 cubic inches (0.3 liters) of additional resonance volume between the hot-film air mass meter and the throttle butterfly and is activated between 5,000 and 6,000 rpm to reduce oscillations in intake sounds. Porsche has applied for a patent for this technology that provides a deep, throaty sound without aggressive peaks.

Higher combustion forces produce more power but also more torsional crankshaft vibration, so Porsche engineers have integrated a vibration damper in the pulley at the end of the crankshaft. Conventional vibration dampers are made of cast iron but Porsche engineers devised an aluminum damper that reduces weight by some 3.3 pounds (1.5 kg) while controlling vibrations to a level even lower than the 3.6-liter engine.

Amazingly, the 3.8-liter engine weighs no more than the 3.6-liter unit thanks to its lighter intake manifold and weight optimization within the cylinder head.

While the 3.8-liter engine uses twin radiators like the 3.6-liter powerplant, it has a higher performingcooling pump and an oil/water heat exchanger with two additional cooling layers.

New six-speed manual transmission

To deal with the new engine’s 295 pound-feet of torque, Porsche developed a new six-speed manual gearbox that is used on both the 2005 Porsche 911 Carrera Cabriolet and the 2005 Porsche 911 Carrera S Cabriolet.

The transmission has thicker shafts and wider gears but weighs no more than the previous manual. Extra-thin aluminum used for oil chamber walls save weight and also reduce splash effect and flow losses and thus increase the efficiency of the gearbox.

Even though gear ratios have been reduced by around five percent, the use of larger rear wheels results in achieving top speed in sixth gear just before maximum engine speed is achieved.

While brass synchronizing rings were formerly used, the new transmission has steel rings in all gears and thus can handle higher power loads. For the first time, Porsche uses wear-resistant carboncoated first, second and third-gear synchronizing rings, and boosts from double to triple synchronizing for first and second gears and from single to double for third gear, retaining single synchronizing for gears four, five and six.

The driver will notice this change in the reduced forces and shorter travel needed to change gears. Shifter travel is reduced by some 15 percent. Shifting also is smoother and more precise because of relocation of the shift lever pivot point and lower-friction shift cables.

Porsche’s single-disc dry clutch with lead-free pads is retained for the 2005 Porsche 911 Carrera Cabriolet while the 2005 Porsche 911 Carrera S Cabriolet gets a new self-adjusting clutch.

Enhanced Tiptronic S available

Tiptronic S is Porsche’s optional automatic transmission system that allows manual gear selection via switches on the steering wheel. The five-speed unit allows the driver to use the thumb switches to change gear momentarily, for example, for passing or to downshift for a curve, even while the floor lever remains in its automatic position.

Several modifications have been made to Tiptronic S in conjunction with the increased torque produced by the 3.8-liter engine in the 2005 Porsche 911 Carrera S Cabriolet.

Now, instead of making the first-second shift at 6,900 rpm under full power acceleration, Tiptronic S holds first gear until the engine achieves 7,200 rpm.

In addition, the oil pressure build-up has been fine-tuned and clutch plates modified to allow the Tiptronic S to shift more smoothly.

Throttle tip-in mimics enthusiast’s driving technique

To mimic the way an enthusiast driver manipulates the accelerator, brake and clutch, changes to the engine management software now produce a slight boost in engine speed during aggressive downshifting, such as that done while applying the brakes. This shortens shift time and enhances gearshift mesh.

The PSM OFF function also has been modified so that when the Tiptronic S selector lever is in its manual mode and the PSM OFF switch is activated, the transmission will not shift up even when the engine reaches its rev limit. This allows the enthusiast driver to drive with the engine near its rev limit while maintaining the selected gear.

As with the six-speed manual transmission, a shorter spur gear ratio works in conjunction with the larger standard rear wheels to achieve maximum top speed in the top (fifth) gear.

To keep the enhanced Tiptronic S operating at proper temperatures, the gearbox is equipped with an additional oil/water heat exchanger with two additional cooling layers and with a more powerful coolant pump.