1991 Porsche 911 Carrera

Porsches new Benjamin Dimson designed generation 911, known internally as the 964, making its debut in 1989 and was available in two (Carrera 2) and four-wheel drive (Carrera 4) guises. Its familiar silhouette had a drag coefficient of just 0.32 thanks to its smoother sills, flatter floorpan, high-speed stability, and deeper bumpers. Power came from a re-worked 3.6-liter air-cooled flat-six engine equipped with twin spark plugs per cylinder and a re-mapped Bosch Motronic fuel injection system. The 250 horsepower engine was mated to a five-speed manual gearbox as standard and most variants could race from zero-to-sixty mph in 5.3 seconds with a top speed of over 160 mph.

Although it was patently still a 911, the new 964 was in fact 85 percent different from the outgoing model. It came with a host of mechanical changes, the most significant of which was the availability of four-wheel drive. The road holding, lift, and stability was greatly improved thanks, in part, to the retractable spoiler which automatically extended at speeds above 48 mph. It offered a serious increase in downforce and also doubled the volume of cooling air fed into the engine compartment. The reshaped nose and tail were now fitted with molded thermoplastic bumper covers. The traditional torsion bar front suspension was replaced with coil springs and shocks. The rear suspension retained Porsche's trailing arms and torsion bars. The brakes had large cross-drilled and ventilated rotors at all four corners. The floor pan was revised to accept a new all-wheel-drive system developed in the 959 and 961, however, all of the highest performing versions of the 964 used the rear-wheel-drive configuration.

The revised instrumentation included a large set of warning lights that were linked to the car's central warning system adding to Porsche's reputation for reliability.

911 Turbo
The original Porsche Turbo Carrera was introduced in 1974; the second-generation Turbo arrived in 1991 with a top speed of nearly 170 mph. The M30/69 engine displaced 3,299cc and offered 320 horsepower at 5,750 RPM thanks to a larger intercooler that reduced the temperature of the intake air and improved volumetric efficiency. It used stainless-steel head gaskets for improved sealing and durability, a revised ignition system, and a metallic catalyst in the exhaust system. The rear track was widened to accommodate the 255/40-17 tires

The Porsche Turbo 3.3 was the world's fastest-accelerating production car at the time and could go from zero-to-sixty mph in just over four seconds and reach the quarter-mile in the 12-second range at 108 mph.

674 examples were made for the United States and had a base price of $97,800. Many were fitted with optional equipment which increased the price even further. The list of options included a limited-slip rear differential, a rear window waster, a full leather interior, sports seats with partial power adjustment and heating, and more.

964 Carrera RS NGT
Porsche produced a lightweight, rear-wheel-drive only version of the 964 called the Carrera RS in 1992. It was given a revised version of the standard engine titled M64/03 internally, which developed 265 horsepower. It had a lightweight flywheel coupled to the G50/10 gearbox with closer ratios, steel synchromesh, and asymmetrical Limited Slip Differential.

To transform the 964 into a lightweight version, the interior was stripped of all non-essential materials including the electric windows, rear seats, air conditioning, sound deadening material, and cruise control. The bonnet was formed from aluminum and the chassis was seam welded. The glass was thinner in the rear window and doors. The removal of these materials made the Carrera RS approximately 155 kg lighter than the standard model.

The NGT models went a step further, with the removal of the soundproofing material and the carpets. The front carpets were replaced with plywood footboards, and the seats were Nomex-covered rather than leather. A full welded cage was installed for safety. All NGTs received a long-range fuel tank, fire suppression system, fire extinguisher release, external cut-off, and a relocated DME.

A total of 290 examples of the Porsche 911 (964) Carrera RS NGT were built.

964-based Carrera Cup
In 1990 Porsche replaced the successful 944 Cup Series with the new 964-based Carrera Cup as a single-model 'Spec-racer' championship. The Carrera Cup series was staged nationally, regionally, and then internationally, often running as support events for Formula 1. For 1991, 120 examples were sold to privateer drivers. The following year, 45 Carrera Cup cars were brought into the United States to run a prospective race series to run as support events for CART races. However, the racing series did not come to fruition, and the cars were quietly converted to street-legal form and sold.

Conceived by Helmut Flegl and Roland Kussmaul, the cars were pulled off the regular assembly lined and tuned to optimal performance on the track. The cars received a full welded-in Wilfried Matter roll cage, a single Recaro racing seat with a six-point safety harness, and a fire-suppression system. Mechanical changes were made to the suspension with shorter springs which lowered the car about two inches. Additionally, Bilstein gas-filled competition shock absorbers, and fully adjustable anti-roll bars, were installed with five pickup points in front and three for the rear. The unassisted steering was upgraded with a faster ratio and brakes were sourced from the Turbo. The 17-inch alloy wheels measured 8 inches in the front and 9.5 inches in the rear. The normally aspirated air-cooled six-cylinder engines ran without air filters and the stock dual-mass flywheel was replaced with a single disc. The electronic engine control units were sealed to prevent tampering.

by Daniel Vaughan | Dec 2019