Whether Coupe or Cabriolet, the 2004 Porsche
911 Turbo draws its power and its name from its 3.6-liter horizontally
opposed “boxer” engine, which provides 415 horsepower (SAE) and 415
lb.-ft. of torque.
But for 911 Turbo Coupe drivers who want
even more power under their control, an optional factory-installed X50
engine enhancement performance package boosts the turbochargers’
pressure to generate 444 horsepower (SAE) and 457 lb.-ft. of torque.
Porsche began using turbochargers in the
famed Porsche 917 racecar in the early 1970s and introduced its first
911 Turbo production model in 1974. The 911 Turbo arrived in the United
States for model-year 1976, and with its 234-horsepower (SAE) engine
could achieve 0-62 miles per hour (0-100 km/h) in 5.5 seconds.
Porsche also pioneered innovations that
increased turbocharging reliability, including the exhaust wastegate to
regulate boost pressure and intercoolers to reduce the temperature of
the compressed intake air.
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 in the United States for 1996.
From the beginning, Porsche designed the
911 Turbo as a fully equipped grand touring car with a high level of
standard luxury features. For 2004, the Porsche 911 Turbo is offered in
two new colors – Atlas Gray metallic and Carmon Red metallic. It also
comes with a special new Turbo tachometer and with two new options:
18-inch SportTechno wheels and 18-inch GT3 wheels.
A racecar-derived 3.6-liter, twin-turbo
six-cylinder engine gives the 911 Turbo staggering performance
capabilities. The engine produces 415 horsepower (SAE) @ 6,000 rpm and
sustains 415 lb.-ft. of peak torque from 2,700 to 4,600 rpm. Power
drives through a standard six-speed manual transmission, with the
advanced Tiptronic® S five-speed automatic transmission as an option.
With power characteristics of a far larger engine, the 911 Turbo Coupe
can accelerate from 0 to 62 mph (0 to 100 km/h) in just 4.2 seconds. On
the test track, the 911 Turbo sprints from a standstill to 99 mph (160
km/h) in only 9.3 seconds and can achieve a top track speed of 189 mph
(305 km/h).
The 911 Turbo engine is based directly on the 3.6-liter engine from the
GT1 racecar that won the 24 Hours of Le Mans in 1998. (The engine is not
a turbocharged version of the 3.6-liter unit used in the 2004 911
Carrera models.) To accommodate the high boost pressure produced by its
dual turbochargers, the engine features a 9.4-to-1-compression ratio,
compared to 11.3-to-1 for the 911 Carrera models. Intake air enters
through louvers in the engine lid, flows into a joint air filter housing
and then into the turbochargers. The turbos compress the air to a
maximum of 11.76 psi (0.8 bar over atmosphere). From the turbos, the
intake air flows through dual intercoolers (one mounted in each rear
fender) and then into the induction system.
Like all current Porsche engines, the 911 Turbo features double overhead
camshafts and four valves per cylinder. The new-generation 911 Turbo
introduced a new version of the Porsche VarioCam® valve timing system.
Called VarioCam Plus, the new system provides continuously adjustable
intake valve timing. The system helps boost low-end and mid-range
torque. Dual valve springs ensure reliable,
high-performance operation. 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. In place of a conventional throttle cable
setup, E-Gas electronically transmits pedal position to the engine
control unit. The new system provides even sharper throttle response and
ensures low emissions.
The 911 Turbo also offers an optional X50 engine enhancement performance
package that increases horsepower to 444 (SAE) @ 5,700 rpm and sustains
457 lb.-ft of peak torque from 3,500 to 4,500 rpm. The new package
includes modifications to the turbocharger, air intake cooler,
electronic control unit,
exhaust system, as well as a strengthened transmission. The X50 package
is only available as an option from the Porsche factory.
The 911 Turbo offers a choice between a precise-shifting standard
six-speed manual transmission and the optional Tiptronic S five-speed
automatic transmission. The six-speed manual features a dual-mass
flywheel for low vibration and a hydraulic clutch for consistent
performance.
With the advanced Tiptronic S, the driver
can place the shift lever into “D”, or Drive, and let the transmission
do the shifting, or shift into “M”, Manual, and control gearshifts with
steering wheel-mounted thumb switches. In automatic mode, Tiptronic S
uses infinitely variable shift points to respond to the driving
circumstances and the driving style. During leisurely driving, Tiptronic
S up shifts early to provide a quiet ride and the best fuel efficiency.
With quicker gas pedal action, the transmission responds by raising
shift points to hold each gear longer for crisp response and power.
The Tiptronic S transmission draws from among 250 different shift maps
to provide optimal performance. Even while in automatic mode, the
computer-controlled Tiptronic S responds like a driver working a manual
transmission, downshifting or holding lower gears when cornering and
driving on hills. Tiptronic S allows the driver to select manual mode by
pressing an up- or downshift button, even with the shift lever in the
“D” position.
The 911 Turbo uses an all-wheel drive
system based on a viscous multi-plate clutch located directly behind the
front differential. Weighing only 120 pounds (54 kg), the all-wheel
drive system in the 911 Turbo qualifies as one of the lightest such
systems in the industry.
The all-wheel drive system directs torque
to the front wheels at a rate of five to 40 percent, depending on
available traction and power applied. The viscous unit compensates for
differing wheel speeds during cornering. The 911 Turbo exhibits
outstanding traction on all road surfaces. However, Porsche did not
originally intend the all-wheel drive system as an all-weather traction
assistant.
Porsche equips the 2004 911 Turbo with
the Porsche Stability Management system (PSM), an innovation the
automaker first introduced on the 1999 911 Carrera 4. Using data from
several sensor inputs, PSM can detect a loss of grip at the front or
rear and reduce instability by applying braking to individual wheels
and, if necessary, altering engine power. PSM can help keep the 911
Turbo going in the direction the driver steers, especially on slippery
roads.
The PSM system operates so quickly that most drivers likely will not
feel it making corrections, and, if activated, the system operates
whether or not the driver is using the brakes. The driver can disengage
PSM with a dashboard switch, but, for safety, PSM will engage under
braking and then disengage when the driver lifts off the brake.
