Porsche 911 Turbo
From the first Porsche 911 Turbo, this top model has always stood apart from other Porsche 911 models by virtue of functional design differences. Nothing has ev...More »
Porsche 911 Turbo
From the first Porsche 911 Turbo, this top model has always stood apart from other Porsche 911 models by virtue of functional design differences. Nothing has ever been added that didn't serve a purpose, and nothing has ever been tacked on for the sake of appearance. From that purpose-driven design evolved a distinctive "Turbo look," highlighted by widely flared fenders, a widened rear stance, and a distinctive rear spoiler.
That the function-driven design has created the most recognizable supercar shape in the world is just a coincidence.
The New "Turbo Look"
The 2001 911 Turbo continues that tradition and stands apart from the
models with all-new front and rear styling and a wider stance. In front, the Porsche 911 Turbo features unique bi-xenon headlight clusters that use xenon high-intensity discharge headlights for both the low and high beams.
Three large intake grills dominate the lower front fascia and provide cooling air to the car's three radiators. Together, the three radiators provide 50 percent more cooling surface than in the
911 Carrera 4
. Underside guide plates in the middle and on the sides prevent the warm air exiting the radiators from causing axle lift. The front spoiler reduces airflow under the car, helping to reduce axle lift force. Two intakes in the spoiler supply cooling air to the brakes through ducts.
Wider Rear Track
At the rear, Porsche widened the 911 Turbo by 2.6 inches (65 mm) to accommodate the 18-inch alloy wheels and massive 295/30 ZR18 tires. The Turbo-trademark red-painted alloy brake calipers are plainly visible through the wheel spokes. The widened rear quarter panels also place the intercooler intakes into the air stream. Compared to the Carrera 4, the Porsche 911 Turbo rear track is wider by 1.57 inches (40 mm).
Louvers in the lower rear fascia vent air from the engine compartment. A different taillight design from the 911 Carrera 4 further distinguishes the 2001 Porsche 911 Turbo.
The "Whale Tail" Era Closes
Porsche has replaced a fixture of 911 Turbo design since the first model - the "whale tail" spoiler. Used first as an aerodynamic aid and to vent the engine compartment, the wing later grew to help house the engine intercooler. Since the 2001 911 Turbo houses its intercoolers behind the rear wheels, Porsche aerodynamicists designed a more subtle spoiler. The new two-piece rear wing resembles the "ducktail" spoiler first seen on Porsche Carrera models of the early 1970s. The resemblance ends when the upper part automatically raises at speeds above 75 mph (120 km/h) to prevent lift force on the rear axle. The wing retracts when car speed drops below 50 mph (80 km/h). At the car's top track speed of 189 mph (308 km/h), the wing adds 20 pounds (9 kg.) of downforc e .
A smooth underbody design and various underbody panels guide airflow under the car to reduce drag and lift. In front and rear, small, flexible spoiler lips at the front of the wheel arches also help reduce drag and lift. The rear underbody cover guides airflow to the back of the car without impeding heat dissipation or access to the powertrain. Despite the wider stance compared to the 911 Carrera 4, the 2001 Porsche 911 Turbo meets the air with an impressive 0.31 coefficient of drag (Cd), compared to 0.30 for the 911 Carrera 4.
The Bi-xenon headlights that give the 2001 Porsche 911 Turbo such a distinctive look also introduce the world's first use of this high-intensity gas-discharge technology to provide both low and high beams. Other systems, including the Litronic xenon lights on other Porsche models, provide xenon lights for the low beams only.
The bi-xenon lights provide both low and high beams from a single gas-discharge bulb and project light through a 70-mm lens. A moving mask provides the different light distribution required for low/high beams. When raised, the mask allows enough light to pass to create the low beam. Lowering the mask opens a greater path for the light to create a high beam effect while maintaining the bright/dark barrier required by law. The mask moves in a fraction of a second, allowing a high beam flasher function.
The standard headlight washer system uses high-pressure spray nozzles integrated into the headlight clusters. The closeness of the nozzles to the lenses makes the spray more effective than before.
The Porsche 911 Turbo provides 2+2 seating, and the individually folding rear seats provide a versatile space for luggage. The Porsche 911 Turbo shares its basic interior design with the 911 Carrera 4 but adds many enhancements and standard luxury features over and above the standard equipment in that model, including:
full leather interior (front and rear seats, door panels and instrument panel all covered in leather)
power-adjustable seats for the driver and passenger (with driver's side memory)
onboard computer with boost gauge
premium sound system with 10 speakers and six-channel amplifier
three-spoke leather covered steering wheel with Porsche Crest
programmable remote entry and security system with alarm and immobilizer
choice of 12 paint colors (seven metallic, each with no extra charge)
new LED (light emitting diode) interior orientation lights
The ignition key integrates the remote entry control and allows the driver to open the luggage compartment lid and operate the seat memory function. Standard equipment shared with the 911 Carrera 4 includes:
power windows with one-touch up/down
power opening for the luggage compartment lid
heated windshield washer nozzles
heated power sideview mirrors
right sideview mirror with "tilt down" function to aid parking
Tradition Meets Technology
Owners of previous 911 or 911 Turbo models will feel right at home with the ignition switch to the left of the steering wheel and the gas pedal pivoted from the floor. Porsche broke with previous 911 Turbo tradition, however, and suspended the brake and clutch pedals from the dashboard instead of the floor.
The large center instrument pod houses the tachometer, the lower middle portion of which includes the display screen for the standard onboard computer. The dot matrix display shows turbo boost and basic settings including total and trip mileage. In addition, the driver can call up oil level, exterior temperature, fuel consumption and estimated driving range - 35 alerts in all.
The analog speedometer to its left includes a small digital speed readout. The far-left gauge contains a battery gauge. The pod to the right of the tachometer contains the coolant temperature gauge, fuel gauge and oil level indicator. On Tiptronic-equipped cars, this pod also includes the gear indicator. The rightmost pod contains an oil pressure gauge.
LED Orientation Lights
Porsche designers discretely placed light-emitting diode (LED) orientation lights in the cabin to provide soft flood lighting for certain controls. One LED integrated within the main interior light softly lights the entire cockpit and center console. This LED provides just enough light to help the driver more easily find controls at night, but does not distract as the main white light would if turned on. The driver can adjust the light level between two settings.
Another LED housed in the left door handle casts a beam onto the ignition and light switch area. One yellow LED in each door recess helps the driver and passenger easily locate the door handles.
The center console houses the climate control and stereo system. On cars equipped with the optional Porsche Communication Management (PCM) system, the PCM screen and control panel occupy the upper section of the console, and the climate control system occupies the lower section. The PCM integrates Global Positioning Satellite (GPS) navigation and the climate control system.
For precise navigation, the PCM uses navigation maps on CD-ROM discs (produced by Navigation Technologies) and a GPS antenna mounted in the dashboard, wheel speed sensors and a gyroscope. The system reads directions aloud and displays the car's pro g ress via onscreen maps. The driver or passenger can enter specific addresses or various points of interest.
Like a house, a car is only as strong as the foundation on which it is built. Commonly called a "chassis," the foundation really encompasses the car's body structure, front and rear suspension and brake systems. Just as a solid foundation provides the basic integrity and strength in a house, a car's foundation largely defines its handling responsiveness, passive safety capability, ride comfort, and long-term durability. "The stronger the better" applies equally to the foundations of houses and cars.
Porsche has achieved significant gains in body stiffness over the previous-generation Porsche 911 Turbo, increasing torsional stiffness in the 2001 model by 49 percent and bending stiffness by 82 percent.
The Strength of Steel
The Porsche 911 Turbo unit body incorporates welded box sections and bolt-on front fenders. Steel makes up the entire unit body structure, including high-strength low-alloy (HSLA) steel and boron steel for high-load and safety-critical areas.
Aluminum accounts for about 20 percent of the car's weight. However, Porsche uses aluminum mainly for the mechanical systems, including the engine, the transmission case, suspension components, brake calipers, and wheels. The automaker believes steel provides the best combination of strength, safety, weight, and repairability for the unit body and exterior body panels.
Porsche builds a small percentage of the Porsche 911 Turbo structure - the front bulkhead, rear inside sidemembers and rear floor section - using tailored blanks. Offering greater rigidity than large single pressings - especially for complex shapes - t a i l o red blanks start as separate sheet steel pieces made from diff e rent thickness and properties. Laser welding subjects the pieces to little heat, producing one larger distortion-free blank. Deep-drawing the blank produces a tailor-made panel of exceptional strength, yet low weight.
Designed for pure driving pleasure, the new Porsche 911 Turbo also offers extraordinary passenger protection. Advances in passive safety - the ability of the car and its systems to protect the occupants in a collision - include a Porsche-patented design for front and rear impact energy absorption and dissipation, an extremely rigid passenger compartment, and the Porsche Side Impact Protection System.
Because the term "crumple zone" has become commonplace in the auto industry, it's important to describe the Porsche-patented system. In a frontal impact, several defined energy paths direct impact energy toward the high-strength steel bulkhead and sidemembers. Front and rear crumple zones protect the extre m e l y rigid passenger compartment.
Porsche arranged front impact protection in two tiers. The first tier includes the front lateral body shell members. The front longitudinal members and bulkhead crossmembers behind the luggage compartment form the second tier. The front-mounted fuel tank and fuel pipes lie outside the crumple zone. The rear crumple zone dissipates crash energy in a similar way, with the rear bulkhead designed to prevent engine intrusion into the passenger compartment.
Porsche has equipped all its cars with dual airbags as standard equipment since 1989.
In the 2001 911 Turbo - as in the 911 Carrera models - the Porsche Side Impact Protection System includes boron steel door reinforcement beams, energy-absorbing door panels, and door-mounted side airbags. The 30-liter capacity sidebags provide protection for the chest, head and pelvis. Airbags supplement the protection offered by the three-point seatbelts.
At a customer's request, a Porsche dealer can install a system that deactivates the passenger airbags when a Porsche-approved child seat is used. The system features a cross brace with belt lock in front of the passenger seat. Buckling the special child seat into this brace deactivates the airbags. To install the system, the dealer also must reprogram the airbag control module.
GT3 Chassis Parts
The 2001 Porsche 911 Turbo offers a combination of handling response and everyday ride comfort not usually associated with cars of its performance level. The Porsche 911 Turbo is equally adept at commuting as it is at shining at high-performance racetrack driving events. Compared to the previous Porsche 911 Turbo, the new model features a 3.2-inch longer wheelbase to accommodate new crash structures and to improve stability and ride comfort. Although the suspension layout is the same as in the 911 Carrera, the 911 Turbo adopts several parts from the 911 GT3 (a normally aspirated, limited-production model not imported to North America), including mounting points for the car's main systems and the longer rear track control arms.
The Porsche-optimized MacPherson strut design uses aluminum lower control arms, aluminum wheel carriers, an aluminum crossmember, coil springs, twin-tube gas-charged shock absorbers and a 0.95-inch (24 mm) diameter stabilizer bar. The aluminum crossmember carries the lower control arms, diagonal steering arms, and the rack-and-pinion steering.
The MacPherson strut design provides exceptional lateral and longitudinal rigidity with low unsprung weight. Negative steering offset helps stabilize the car under varying braking forces, including ABS intervention. The suspension geometry reduces brake dive.
The Porsche 911 Turbo models feature a refined version of the multilink suspension introduced on the previous-generation Porsche 911 Turbo. The suspension components mount to an aluminum subframe, which itself provides lateral reinforcement and noise isolation for the unit body.
Five aluminum control arms locate each wheel - three lower control arms (toe control arm, transverse arm and diagonal strut) and two upper control arms. Conically shaped, progressive rear springs mount non-concentrically around monotube shock absorbers (versus twin-tube shocks in the front). As in the front, spring and shock absorber tuning are tighter than in the 911 Carrera 4. A 0.87-inch (22 mm) stabilizer bar completes the setup. Suspension geometry reduces squat during acceleration.
Longer rear track control arms from the racecar-based 911 GT3 widen the rear track of the Porsche 911 Turbo by 1.57 in. (40 mm) over the 911 Carrera 4.
The rear suspension features the "Weissach axle" toe-control concept - so named for its development at Porsche's Weissach, Germany Research and Development Center. During cornering, the toe control arms effect slight toe-out on the outside wheel and slight toe-in on the inside wheel. This self-steering response helps generate stable, neutral handling in the Porsche 911 Turbo.
Derived from the Porsche GT1 racecar (and also used on the 911 GT3 and 911 Carrera models), the 911 Turbo four-wheel vented disc brakes use innovative one-piece ("monoblock") brake calipers that contribute to quick brake release for reduced heat and optimal brake pedal travel and feel. The monoblock design reduces unsprung weight because it does not require the connection bolts of a two-piece caliper. The four pistons in each caliper vary in diameter to help prevent uneven brake wear, and, compared to the 911 Carrera 4, the 2001 911 Turbo uses larger, reinforced calipers.
The front and rear brake discs from the 911 GT3 measure 13.0 inches in diameter (330 mm), but differ in thickness - 1.34-inch (34 mm) in front and 1.1-inch (28 mm) in the rear. Overall, the larger brakes provide five percent more swept area compared to the previous Porsche 911 Turbo.
The cross-drilled discs dissipate heat to maintain braking performance and brake feel even under hard usage. By comparison, the 300-horsepower 911 Carrera 4 uses the same brake system, but with smaller discs -- 12.5-inch diameter x 1.1-inch thick (318 mm x 28 mm) in front and 11.8-inch diameter x 0.95-inch thick (299 mm x 24 mm) in the rear. Cooling air flows to the front discs through two ducts and through guide spoilers on the longitudinal suspension arms.
World's First Ceramic Brake Discs
The 2001 Porsche 911 Turbo introduces the first ceramic composite brake discs on a production car. The Porsche Ceramic Composite Brake (PCCB), available as an option, will set new standards for brake response, fade resistance, and service life. Porsche dealers can retrofit the discs to 2001 911 Turbos originally ordered without the option.
While about the same size as the standard cast iron brake discs, the PCCB weighs 11 pounds less per wheel - a 50 percent weight reduction. The lower weight reduces unsprung mass and improves suspension response. The PCCB provides optimal braking performance even under extreme conditions, on dry or wet roads.
An extremely hard disc surface together with immunity from salt corrosion will give the PCCB a long service life. Combined with new composite metal brake pads, the discs provide more consistent friction than iron discs during hard, repeated braking. The new composite pads absorb less water than conventional brake pads, improving braking performance in wet driving conditions. In addition, the new pads should last twice as long as conventional pads.
Super-Wide Wheels and Tires
Commensurate with its massive power, the 2001 Porsche 911 Turbo rides on massive wheels and super wide, low-profile performance tires. The 18-inch diameter wheels of the 2001 Porsche 911 Turbo are unique to this model and measure eight inches wide in front and 11 inches wide in the rear. The front wheels mount 225/40 ZR18 tires, and the rears use 295/30 ZR18 tires.
The Heart of A Le Mans Winner
The all-new fourth-generation Porsche 911 Turbo makes a drastic departure in engine philosophy from its predecessors. Previous models used turbocharged versions of air-cooled Carrera engines in 3.0, 3.3, and 3.6-liter form. However, the engine in the 2001 911 Turbo is not a turbocharged version of the engine from the current 911 Carrera models. Instead, Porsche derived the 3.6-liter, horizontally opposed six-cylinder engine in the 2001 911 Turbo from the Porsche GT1 racecar, which won the 24 Hours of Le Mans in 1998.
Liquid cooling, used for the first time in a Porsche 911 Turbo, allowed significant increases in both compression ratio and turbo boost pressure. The new Porsche 911 Turbo engine uses a 9.4-to-1 compression ratio, compared to 8.0-to-1 for the previous air-cooled Porsche 911 Turbo. (The first 911 Turbo, by further comparison, used a 6.5-to-1 compression ratio!)
415 Horsepower and Optional Tiptronic S
The Porsche 911 Turbo engine produces 415 horsepower (309 kW) @ 6,000 rpm and sustains 415 lb.-ft. (560 Nm) of peak torque from 2,700 rpm to 4,600 rpm. Power drives through a standard six-speed manual transmission. For the first time in a 911 Turbo, Porsche offers the advanced Tiptronic S five-speed automatic transmission as an option.
With power characteristics of a far larger engine, the 2001 911 Turbo (six-speed) can accelerate from 0-62 mph (0-100 km/h) in just 4.2 seconds. On the test track, the Porsche 911 Turbo will sprint from a standstill to 100 mph (160 km/h) in only 9.2 seconds and can achieve a top track speed of 189 mph (305 km/h).
When equipped with the optional five-speed Tiptronic S automatic transmission, the 2001 Porsche 911 Turbo offers still-staggering performance: 0-62 mph (0-100 km/h) in 4.9 seconds; 0-100 mph (0-160 km/h) in 10.6 seconds and a top track speed of 185 mph (298 km/h).
The Porsche 911 Turbo engine shares the GT1's pressure-cast light-alloy split crankcase, and the crankshaft runs through eight bearings. The stroke measures 3.01 in (76.4 mm) and the cylinder bore measures 3.94 in. (100.0 mm) for a displacement of 3,600 cc (220 cu. in.). Each side of the crankcase (cylinder block) includes a separate cylinder head and camshaft housing, both of which bolt to each crankcase side. In contrast, in the 911 Carrera engine, the cylinder and crankcase sections form one unit. The modular construction reveals the engine's racing heritage - it facilitates displacement changes to comply with ever-changing racing regulations.
The Porsche 911 Turbo does use the same kind of racing-derived crossflow cooling as the 911 Carerra 4 engine. Coolant flows crosswise from the hot to the cold side of the engine, ensuring a consistent temperature curve. The coolant system includes an oil cooler. During engine warm-up, the engine coolant helps heat the oil to bring the engine up to operating temperature quickly.
The front of the Porsche 911 Turbo, with its three large intakes, shows off the cooling capacity required by the twin-turbo engine. The central intake feeds a third radiator, which increases the cooling capacity by 50 percent over the two-radiator 911 Carrera 4. The water pump can flow 4,500 gallons per hour - about 800 more than the 911 Carrera 4.
Twin Turbos, Dual Intercoolers
As on the previous-generation Porsche 911 Turbo, the 2001 model uses dual turbochargers, arranged in parallel. Also like the previous Porsche 911 Turbo, the 2001 model uses dual intercoolers, but they're mounted on each side behind the rear wheels instead of on top of the engine.
Intake air enters through an inlet in the rear spoiler that flows into the air filter housing and then into the turbochargers. The turbos compress the air to a maximum of 26.8 pounds per square inch (1.85 bar) - more than double the boost of the previous 911 Turbo. At about 2,500 rpm, wastegates on the turbochargers open to reduce boost to a maximum of 23.9 psi (1.65 bar). From the turbos, the intake air flows through dual intercoolers and then is merged upstream of the throttle butterfly. Porsche was the first carmaker to employ intercoolers for turbocharged cars. The intercooler reduces the temperature of the compressed charge, boosting power and enhancing component longevity.
The 2001 911 Turbo uses a dry-sump lubrication system like that on the Porsche GT1 and GT3. An external oil tank is attached directly to the engine, and the engine uses eight oil pumps - two in the crankcase (one pressure and one scavenging), a double scavenging pump on each cylinder head and one scavenging pump for each turbocharger. This setup keeps oil level in the tank at maximum even under extreme acceleration, braking, and cornering. A cyclone-shaped oil defoamer in the tank ensures a consistent oil supply for lubrication and operation of the VarioCam Plus valve lift and timing system. (The 911 Carrera and 911 Carrera 4 use an integral dry-sump lubrication system.)
The Porsche 911 Turbo lubrication system holds 11.6 quarts (11 liters) of oil. Porsche replaced the dipstick with an electronic oil level monitor that ties in with the standard onboard computer. The driver can check the oil level on the computer display when the car is running at idle speed at normal operating temperature and resting on an even surface.
The Porsche 911 Turbo engine uses double overhead camshafts (DOHC) and four valves per cylinder, compared to the single overhead cam (SOHC) two-valve layout of the previous Porsche 911 Turbo. The 2001 911 Turbo introduces a new version of the Porsche VarioCam valve timing system. Called VarioCam Plus, the new system provides adjustable valve timing plus two camshaft profiles and two sets of tappets to vary valve lift and duration.
Like Two Sets of Camshafts
In normally aspirated Porsche engines, the VarioCam system alters valve timing by using camshaft chain tension to switch the intake camshaft between two positions. The VarioCam Plus system in the 2001 911 Turbo is much different and is really two systems in one. With VarioCam Plus, axial camshaft adjusters move over helical ramps to offer continuous valve timing adjustment.
The "plus" part of VarioCam Plus affects valve lift and duration according to engine load and speed and gear selection. Each intake camshaft includes two sets of lobes to provide two camshaft profiles - a 3-mm low-lift, short-duration p rofile, and a 10-mm high-lift, long-duration profile. The high-lift "lobe" is actually a pair of lobes, one on each side of the low-lift lobe.
Two Sets of Valve Tappets
Likewise, there are two sets of hydraulic tappets - but in this case, it's a "tappet-within-a tappet." Each tappet cup includes two concentric cups joined by a bolt. At idle and low engine speeds and loads, VarioCam Plus positions the camshaft over the central lifter and with oil pressure raises the center tappet above the outer cup. The low-lift cam profile thus operates the zero-lash center tappet and the outer tappet waits in a stand-by mode. The low-lift, short-duration profile ensures higher velocity of the intake charge and minimizes exhaust gas left over from the previous combustion cycle (low overlap). The 3-mm lift mode reduces fuel consumption and emissions at low speeds.
At higher engine loads, where larger overlap would recirculate exhaust gas and boost torque, VarioCam Plus lowers the center tappet and positions the camshafts so that the two high-lift lobes contact the outer tappet. Dual valve springs ensure reliable, high-performance operation. VarioCam Plus also provides better cold starting.
Low-Emission Vehicle (LEV)
VarioCam Plus accounts for much of the fuel consumption improvement in the 2001 Porsche 911 Turbo. That improvement allowed Porsche to reduce the fuel tank capacity from 18.8 gallons to 16.9 gallons and still maintain the same cruising range as the previous model.
In addition, VarioCam Plus helps reduce emissions, enabling the 2001 Porsche 911 Turbo to meet the Euro Level 3 and U.S. LEV standards.
VarioCam Plus requires precision measuring of engine speed, gas pedal position, engine oil and coolant temperatures, and gear selection. The ME 7.8 engine control module meets these requirements. The driver "requests" a certain level of power by gas pedal pressure. The ME 7.8 unit compares this request to its control maps and decides within milliseconds whether VarioCam Plus must cut in. While VarioCam Plus effects a major difference in engine behavior, the driver will only feel a steady building of power, not an abrupt switch.
Sequential multi-port fuel injection features separate fuel mixture control for each cylinder bank, and a coil-on-plug ("distributorless") ignition system provides quick response and reliable operation. The ME 7.8 engine control module incorporates the E-Gas electronic throttle ("drive by wire"). Instead of the gas pedal pulling a cable attached to the throttle valve, it pulls a short cable connected to a pedal value transmitter in the dashboard. The transmitter uses a potentiometer to convert the pedal travel path and speed into an electronic signal. The control module processes the signal, sending it to an electric motor that operates the throttle valve.
By providing full computer control over air intake at all engine speeds, the electronic throttle control enhances throttle response and helps reduce emissions. The system also reduces parts, since it eliminates the throttle linkage and separate idle speed control.
The exhaust system also contributes to the lower emissions of the 2001 911 Turbo. The short exhaust manifolds use two-layer air-gap construction with minimal pipe length to the turbochargers. The short exhaust route minimizes energy loss before entering the turbos, ensuring minimal turbo "lag" for quick response.
There are four catalytic converters - two per side. A pair of small-volume catalysts positioned close to the engine and immediately downstream of the turbos "light off" quickly to reduce cold start emissions. The main catalysts ensure low emissions once the engine has reached normal operating temperature.
The standard six-speed manual transmission in the 2001 Porsche 911 Turbo shares only a shift lever with the six-speed in the 911 Carrera 4. The 911 Turbo required a new transmission to handle the 60 percent increase in torque over the 911 Carrera 4 (415 lb.-ft. [560 Nm] in the Porsche 911 Turbo vs. 258 lb.-ft. [350 Nm] in the 911 Carrera 4).
The transmission uses a new case, reinforced shift cables, and new gearbox mounts. Inside, instead of shrinking the gears onto the shafts, the pinions run on a ring of support teeth (splines). As in a racecar, this design makes the gears easily interchangeable.
The 1st and 6th gear ratios are the same as in the previous Porsche 911 Turbo, but 2nd through 5th have been lowered slightly to take advantage of the new engine's superior low- and mid-range torque. Like other Porsche manual transmissions, the 911 Turbo six-speed uses a dual-mass flywheel to minimize vibration, especially at low speeds.
Tiptronic S Automatic
For the first time in its 25-year history, the Porsche 911 Turbo offers an optional automatic transmission. The Tiptronic S five-speed automatic transmission system used in the Porsche 911 Turbo is also new, with stronger internal components and a major change in the Tiptronic shift logic. The floorshift selector and steering wheel shift buttons are the same as in other Tiptronic-equipped Porsche models.
The Tiptronic S floor shifter includes positions for P (Park), R (Reverse), N (Neutral), D (Drive) and, to the left of D, M (Manual). When shifted into D, the transmission offers full automatic operation of the five gears, yet with greater intelligence and sophistication than traditional automatic transmissions. For example, Tiptronic S downshifts when the driver brakes into a corner. In manual mode, the driver can shift with the Formula 1 racecar-inspired steering wheel controls.
Intelligent Automatic Mode
The Porsche 911 Turbo introduces a new automatic mode shift control to the Tiptronic S transmission. Instead of using five shift maps (as in the 2000 Porsche models), the new version chooses from an infinite number of shift points to adapt to the driving conditions - and the driver.
The transmission responds to leisurely driving with low shift points for relaxed, quiet cruising. Rapid accelerator pedal movement and frequent changes in acceleration - as one might experience on a twisty stretch of road - trigger a change to higher shift points and a strategy that holds lower gears longer. The Tiptronic S will immediately adjust the shift point strategy to the current driving style.
A continuously engaging torque converter lock-up clutch works in all gears except 1st to optimize efficiency. To ensure smooth shifting, the Motronic engine control unit slightly reduces engine torque during gearchanges by retarding ignition timing for a fraction of a second. The lock-up clutch also ensures quick shift response when using the manual mode. When coasting in overrun, the lock-up clutch minimizes load change responses.
The Tiptronic S transmission even behaves like a manual transmission when cornering. As the driver quickly releases the gas pedal while entering a corner, Tiptronic S holds the current gear. If the driver then applies the brake, Tiptronic S downshifts to provide engine braking going into the turn and acceleration when exiting. The Tiptronic S control module recognizes cornering by comparing speeds of the inner and outer wheels.
Sliding the shift lever into M from D at any time gives the driver instant manual c o n t rol of the Tiptronic S transmission. The car will hold the current gear until the driver upshifts or downshifts using thumb switches on the right or left steering wheel spokes. Pushing the "+" button upshifts, and pushing the button marked "- " downshifts. Tiptronic S also allows the driver to shift manually with the steering wheel switches even when the shift lever is in "D". Manual shifts occur quickly, with no loss of tractive force. That is, shifting up or down does not reduce engine speed, as it does when taking your foot off the gas when shifting a manual transmission.
A short-term manual mode allows the driver to shift with the buttons even when the gear selector is in "D." This mode allows the driver to quickly downshift manually to overtake, for example. The transmission will switch back to automatic mode unless the driver makes another manual shift within eight seconds.
No Mere "Manumatic"
The Porsche Tiptronic S automatic transmission offers far more control than the manual shifting option of so-called "manumatic" transmissions in other cars. Performance benefits include:
an active shift function that immediately moves the shift points into a sporty shift map when the driver presses the gas pedal quickly
preventing upshifting in overrun when the driver suddenly releases the gas pedal - before a tight corner, for example
automatic downshifting to the next lower gear when applying the brakes (to use engine braking)
hill recognition - the transmission will hold a gear as long as possible on an uphill or downhill grade
holding a gear through a bend
automatic upshift when the wheels slip to improve vehicle stability
a warm-up program that prevents the transmission from upshifting too soon, helping the engine and catalytic converters reach normal operating temperature quickly
Driving All Four Wheels
Porsche pioneered the all-wheel drive supercar with the limited production 959 of the mid-1980s. Although not imported to North America, the turbocharged 959 became a Porsche legend and paved the way for the first standard - production all-wheel drive Porsche 911 Turbo, which arrived for 1996.
As in the previous-generation 911 Turbo, the 2001 model uses an all-wheel drive system based on a viscous multi-plate clutch. The previous system located the viscous unit in the rear transaxle. In the new-generation Porsche 911 Turbo, Porsche installed the viscous unit directly behind the front diff e rential, simplifying assembly and maintenance and moving some weight to the front.
The all-wheel drive system directs five-to-40 percent of the torque to the front wheels, depending on available traction and power applied. The viscous unit compensates for differing wheel speeds during cornering. While the Porsche 911 Turbo exhibits superior traction on all road surfaces, Porsche did not intend the all-wheel drive system as an all-weather traction assistant.
Because Porsche increased the bending and torsional stiffness of this platform, the new-generation Porsche 911 Turbo eliminates the structural tube that enclosed the driveshaft on the previous car. The all-wheel drive system adds just 120 pounds (54 kg) to the car.
Porsche Stability Management
The standard Porsche Stability Management system (PSM) gives the Porsche 911 Turbo the highest level of stability in racetrack performance driving and adds another measure of dynamic safety on slippery roads. The PSM system also provides traction control to the rear wheels.
PSM can detect any loss of grip at the front or rear wheels and prevent instability by applying selective braking (braking one wheel) to keep the car on course. On slippery roads, PSM can help keep the Porsche 911 Turbo going in the direction the driver steers. On the racetrack, PSM can lend a "helping hand" through the slalom and fast turns.Hide -