1999-2001 Porsche 911 Carrera and 911 Carrera 4 Changes
In line with Porsche's cost-saving agenda, the 996-series used essentially a bigger, stronger version of the Boxster's new horizontally opposed six-cylinder engine. Designated M96, this all-aluminum design marked a first for production Porsche powerplants with full liquid cooling and four valves per cylinder, the latter operated by chain from twin overhead camshafts.
For the new Porsche 911s, the 2.5-liter (151-cubic-inch) Boxster engine was bored and stroked from 3.4 x 2.8 inches (85.5 x 72 mm) to 3.78 x 3.07 (96.0 x 78.0 mm), yielding total capacity of 3.4 liters (207 cid). Other upgrades included a forged crankshaft and connecting rods to replace cast components, plus Porsche's Varioram three-stage intake system. The latter was simplified from its 993 application by switching from sliding to fixed intake tubes.
Large or small, the M96 featured VarioCam, the Porsche-patented variable-valve-timing system first seen on the four-cylinder 968 models. In brief, VarioCam used a sliding piston at the timing chain to alter intake-valve closing and overlap as signaled by a Bosch Motronic M 5.2 engine management computer.
The new Porsche 911's engine was basically the Boxster unit upsized to 3.4 liters.
Other shared features included liner-less cylinder walls impregnated with silicon by the new Lokasil process and what Porsche termed "integrated dry sump" lubrication, with the oil reservoir neatly contained within the engine block.
Though smaller than the 993-series' M64 air-cooled six, the wasserboxer was more potent. Horsepower went from 282 at 6,300 rpm to 296 at 6,800, while torque rose from 250 pound-feet at 5,250 rpm to 258 at 4,600. The redline went up, too, from 6,700 to 7,300 rpm, so the M96 was zingier at the top end as well as torquier at lower revs.
And thanks to water cooling, VarioCam, Varioram, and more precise multipoint fuel injection, it rated 10 percent better EPA fuel economy than its predecessor while producing fewer emissions and less noise. A revised exhaust system for year-2000 models liberated an extra four horsepower for an even 300 total, though torque was unaffected.
Matching the new Porsche Carrera engine were two new transmissions, each with an extra cog: a standard six-speed manual, supplied by Getrag, and a five-speed Tiptronic S automatic, from ZF. The latter was newly available for Carrera 4s because Porsche made room for it by moving the power-apportioning viscous coupling from the rear (at the nose of the transmission) to near the front differential. This also slightly improved front/rear weight distribution, from 38/62 percent to 40/60.
Because the 996 bodyshells were so much more rigid than the 993's -- by no less than 45 percent in torsion and a 50 percent in bending -- Porsche could eliminate the torque tube around the driveshaft to the front, saving nine pounds. Engineers were not just cost-conscious with the 996, but weight-watchers, too.
A stiffer platform enables the suspension to work better, and the 996 had a better suspension to take advantage of it. This retained all-round coil springs and modified front MacPherson-strut geometry, but the rear employed a new five-link arrangement, described by Car and Driver as comprising "1 lateral link, 1 trailing link, 2 diagonal links and 1 toe-control link per side." That sounds complex, but it amounted to an evolution of the 993's long/short-arm geometry, again with strut/damper units and provision for stabilizing rear-wheel toe-in during hard cornering.
Further enhancing stability, the rear suspension subframe was now integral with the structure, not separate on rubber mounts, though a discrete front subframe continued. As ever, most suspension components were rendered in weight-saving aluminum.
Predictably for Porsche, the new Carreras boasted larger vented and cross-drilled antilock disc brakes with diameters of 12.5 inches fore, 11.8 aft. These were clamped by new four-piston calipers that created less drag and cost less to make.
The bigger brakes necessitated inch-larger wheels, so the standard alloys were now 7 x 17s fore and 9 x 17s aft; 18s in the same widths were optional. Tires were Z-rated, again in staggered sizes. Standard rubber was 205/50 front, 255/40 rear. The optional 18-inch boots were 225/40 and 265/35, respectively.
Porsche also revised and repositioned the rack-and-pinion steering for better feel, less kickback, and a nearly four-foot tighter turning radius.
Check out the complete story of Porsche cars, including these fabulous models:
|Porsche 356 ||Porsche 911 ||Porsche 914 |
|Porsche 924, 944, 968 ||Porsche 928||Porsche 959|
|Porsche Boxster||Porsche Cayenne||Porsche Cayman|
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