Guide: Porsche 911 Turbo & Turbo S (996)
Background
Having been among the most consistent advocates of turbo technology for approaching three decades, by the late 1990s Porsche had produced forced induction 911s on a trio of different platforms: the 930, 964 and 993.
With his in mind, there was no question the firm would create a turbocharged variant of the heavily revised 996 that had been launched in September 1997.
For several reasons the 996 was perhaps the most significantly revamped 911 yet. Famously, it utilised a bigger bodyshell and a water instead of air-cooled engine (both firsts for the 911). Just as importantly, the 996 shared many of its components with the entry-level 986 Boxster that had arrived a year earlier.
While the technical progress represented by the Boxster and 996 were essential in order to comply with the latest global safety and emissions legislation, the two cars also took a massive leap forward in terms of manufacturing efficiency.
Prior to their arrival, Porsche’s production methods had been stuck in the dark ages. To address the situation, Toyota were consulted and Just in Time manufacturing techniques adopted for what were the firm’s first clean sheet models in around two decades.
To further save money, a common parts strategy was adopted between the 996 and Boxster; the two cars shared engine and suspension components, the same front chassis and an array of exterior and interior equipment.
Following the successful roll out of the rear-drive 996 Carrera Coupe in late 1997 (for the 1998 model year), Porsche went on to add a Cabriolet in early 1998 and an all-wheel drive Carrera 4 around the middle of that year.
A hot GT3 was subsequently introduced at the Geneva Motor Show in March 1999; the GT3 was a rear-drive Coupe conceived as a modern day successor to the legendary Carrera RS line and served to homologate the most extreme normally aspirated 911 possible for GT racing.
Six months after the GT3 broke cover, Porsche introduced their highly anticipated 996-based Turbo at the Frankfurt Motor Show in September 1999.
As per its 993 predecessor, this fourth generation 911 Turbo would come with twin blowers and full-time four-wheel drive. Its engine was based on the GT1-derived motor from the 996 GT3.
Deliveries began in May 2000 with the Turbo initially offered as a Coupe only. For the first time on a forced induction 911, customers could now specify a Tiptronic gearbox.
A Cabriolet version followed three years later following its launch at the Frankfurt Motor Show in September 2002.
Chassis
The starting point for each 911 Turbo was the fully galvanised and reinforced 996 Carrera 4 Coupe-type steel bodyshell. As a consequence of its longer wheelbase and wider track than the outgoing 993, cockpit space was much-improved.
Front suspension was via MacPherson struts while the back end used a multi-link arrangement. Lightweight alloy control arms were fitted along with coil sprung Bilstein dampers and anti-roll bars at either end.
Compared to a standard 996, the Turbo ran a 10mm lower ride height with re-calibrated springs and dampers. Thicker anti-roll bars were also installed.
The 911 Turbo’s brake system was imported directly from the GT3. It comprised 330mm diameter cross-drilled and ventilated discs all round plus four-piston aluminium monobloc Brembo calipers finished in high gloss red paint. ABS software was the latest Bosch M5.3.
As per all four-wheel drive 996-type 911s, Porsche Stability Management (PSM) came fitted as standard. PSM was a sophisticated anti-skid control system that oversaw the ABS (anti-lock brakes), ASR (traction control), ABD (automatic brake differential) and EBV (electronic brake-force distribution). The PSM system was programmed to recognise when the limits of adhesion had been passed by taking inputs from individual wheel speeds, acceleration and deceleration.
New 18-inch diameter five-spoke wheels were 8-inches wide up front and 11-inches wide at the back. They were originally shod with Michelin Pilot Sport tyres.
As per non GT3-type 996 variants, a 64-litre fuel tank was fitted underneath the front lid.
Engine / Gearbox
Instead of the M96/20 engine found in the regular 996, the new 911 Turbo’s motor was based on the GT3’s M96/76 unit which was in turn derived from the Hans Mezger-designed GT1 lump.
Like the GT3 engine, the Type M96/70 Flat 6 fitted in the 911 Turbo featured the same long Mezger block and low friction valve train plus lightweight forged pistons and a nitride-hardened lightweight crankshaft. It did not, however, come with the GT3’s expensive titanium connecting rods.
Displacement was an unchanged 3600cc thanks to a bore and stroke of 100mm and 76.4mm respectively.
Porsche added a pair of intercooled KKK K64 turbochargers which were conservatively set at 0.8 bar. As a consequence of this reserved boost pressure, the M96/70 engine was able to run a comparatively high compression ratio of 9.4:1 (down from 11.7:1 on the GT3).
The Bosch Motronic ME 7.8 digital engine management was custom mapped for this latest application.
As per the rest of the 996 range, the Turbo engine was a water-cooled all-alloy Flat 6 with dual overhead camshafts and four valves per cylinder. In order to accommodate the long block Mezger engine in the 996 engine bay, Porsche Motorsport devised a new dry-sump lubrication system with the oil tank mounted on the engine block.
A unique feature of the M96/70 motor was its VarioCam Plus system which added variable lift as well via variable hydraulic tappets to the original VarioCam system (which featured phase-shifting variable valve timing on the intake valves).
Peak output was 414bhp at 6000rpm and 413lb-ft at between 2700rpm and 4600rpm.
For comparison, the GT3 motor pumped out 360bhp at 7200rpm and 273lb-ft at 5000rpm.
Transmission was through a Getrag G96 six-speed manual gearbox, a reinforced clutch and viscous clutch four-wheel drive system that sent 5-40% of the torque to the front axle depending on conditions.
As a no cost option, the new 911 Turbo could be ordered with a Tiptronic gearbox. The five-speed Tiptronic S unit available on the 996 Turbo offered the choice of either fully automatic shifts or gear changes via steering wheel-mounted actuators.
Bodywork
In a fashion typical of Porsche’s Turbo flagships, this latest forced induction model came with a variety of visual tweaks.
At the front of the car was a new bumper assembly that housed a trio of large intakes to feed the brakes and radiator. Underneath was a satin black wraparound chin spoiler complete with a brace of additional ducts. Located further up were re-shaped Bi-Xenon headlight clusters with clear indicator lenses.
Down each flank were subtly flared fenders: at 1830mm the Turbo was 65mm wider than a regular 996 Carrera. Deep side skirts lent a sporty appearance and were given a two-tone body colour and satin black finish to match the front bumper. To feed the side-mounted intercoolers, Porsche carved a vertical duct from each of the rear fenders.
The back end featured a unique Ducktail rear spoiler complete with active upper plane that extended into the airflow above 70mph (120kmh). There was also a custom rear valance with large cooling vents behind the wheels and semi-elliptical cutaways for the re-shaped twin-pipe exhaust system.
Body panels were fabricated from steel with the exception of the deformable plastic bumpers.
Interior
Inside, the new 911 Turbo imported all its fixtures and fittings from the regular 996.
Behind the three-spoke steering wheel was a traditional five-gauge dash with a centrally mounted 8000rpm rev counter (instead of the 7000rpm item fitted to regular 996 variants). Off to the left was a speedometer and voltmeter while on the right was a combined oil temperature / fuel gauge and an oil pressure dial. Digital read outs at the base of the three main instruments provided the driver with all manner of additional information.
The rest of the switchgear was mounted on the central console along with the ventilation controls and audio system.
Electric windows, electric heated mirrors, leather upholstery and air conditioning were standard for all markets.
As a consequence of the bigger 996 bodyshell, cockpit space was much-improved. A happy by-product of the new water-cooled engine was that Porsche were finally able to install a decent heating system.
Options
The new 911 Turbo became the first series production road car to be offered with carbon ceramic brake discs. In addition to increased stopping capacity, carbon discs represented a 50% weight-saving over the cast-iron items fitted as standard.
Other performance upgrades included adjustable suspension, hard-backed sports seats (available with painted backs), a short shifter and sports exhaust.
Wheel centres and brake calipers could be specified in any colour. Body coloured intake vanes were also available along with highly polished wheels.
To add an extra touch of luxury and personalisation inside, Porsche offered extended leather, two-tone upholstery, heated memory seats, Porsche crested headrests, draped leather, coloured seatbelts, coloured instrument faces, an electric sunroof, a choice of audio systems, an in-car telephone (or telephone preparation) and a choice of wood, aluminium or carbonfibre inserts (to include for the steering wheel, gear knob and handbrake lever).
For added practicality there was the aforementioned Tiptronic gearbox, Porsche Communication Management with GPS and a roof rack.
Given suitably deep pockets, practically any level of customisation could be requested through Porsche’s Exclusive department.
Weight / Performance
At 1540kg the 911 Turbo weighed 95kg more than a standard Carrera 4 Coupe.
Top speed was 190mph and 0-62mph took 4.2 seconds.
The Tiptronic-equipped variant was 45kg heavier (1585kg) and was seven tenths slower to 62mph (4.9 seconds). Top speed dropped to 185mph.
2002 Model Year
For the 2002 model year (production of which got underway in September 2001), Porsche added an X50 power upgrade to the options list.
The X50 kit comprised turbochargers with their boost pressure hiked from from 0.8 to 0.9 bar, larger intercoolers, re-mapped engine management, a free-flow exhaust and a reinforced gearbox.
Peak output was 444bhp at 5700rpm and 457lb-ft between 3500rpm and 4500rpm.
For comparison, the standard Turbo produced 414bhp at 6000rpm and 413lb-ft at between 2700rpm and 4600rpm.
With a 0-62mph time of 4.1 seconds and 193mph top speed, the X50 Turbo bridged the gap to the substantially more expensive rear-wheel drive GT2 that had been unveiled at the Detroit Motor Show back in January 2001.
Another new option was an Aero Kit that featured a fixed dual-plane rear spoiler. When the Aero Kit was specified, the existing chin spoiler and side skirts became entirely body coloured.
A Bose stereo and rain-sensing wipers were added to the list of extras.
Changes made to the base specification included a modified glovebox, new centre-mounted cup holders and a different central air-conditioning vent.
2003 Model Year
At the Frankfurt Motor Show in September 2002 Porsche unveiled a production-ready 911 Turbo Cabriolet.
It was the first time a turbocharged 911 had officially been offered in Cabriolet trim since the old 930 was discontinued in 1989.
The 996 Turbo Cabriolet featured a beefed up bodyshell with reinforced sills and B-pillars.
It could be specified with an aluminium hardtop as an optional extra.
The manual version weighed 1660kg. It had a top speed of 190mph and 0-62mph time of 4.3 seconds.
The Tiptronic version weighed 1700kg. It had a top speed of 185mph and 0-62mph time of 4.9 seconds.
Five-spoke Sport Techno design wheels were a new addition to the options list.
All 911 Turbos now came with a 16 bit microprocessor upgrade.
2004 Model Year
No major changes are believed to have been made for the 2004 model year.
2005 Model Year - Turbo S
The 2005 model year (production of which began in September 2004) was the last for the 996 Turbo.
To give the ageing model a commercial boost in the face of the normally aspirated 997’s arrival, Porsche began to fit the X50 Power Kit and Carbon Ceramic Brakes as standard. To reflect their higher specification, these cars were re-branded as Turbo S variants with appropriate script added to the door entry plates and engine cover.
Those customers that ordered a Turbo S Cabriolet automatically received an aluminium hardtop.
End of Production
996 Turbo production ended in August 2005 by which time 21,954 had been completed.
This figure comprised 16,965 examples of the Turbo Coupe, 3426 examples of the Turbo Cabriolet, 600 examples of the Turbo S Coupe and 963 examples of the Turbo S Cabriolet.
The replacement 997 Turbo was subsequently unveiled at the Geneva Motor Show in February 2006.
Text copyright: Supercar Nostalgia
Photo copyright: Porsche - https://www.porsche.com
