The 911 Carrera 4 combines the 911's legendary performance with the benefits of all-wheel drive (AWD). Much of its drivetrain technology was developed in the exotic, limited-production Porsche 959.

For 1994, the Porsche Carrera 4 is available only in coupe form, with Porsche's 5-speed manual transmission. For the first time, the Carrera 4 incorporates the wider fender flares of the 911 Turbo 3.6 as standard equipment. The Turbo-look body covers suspension and brake components shared with the Turbo 3.6. Like the Carrera 2 and 911 Speedster, the Carrera 4 employs a speed-sensitive rear spoiler, which extends at speeds above 50 mph to provide added aerodynamic stability and extra cooling air for the engine.

ALL-WHEEL DRIVE SYSTEM

Electro-hydraulic differentials control torque split

The Porsche Carrera 4 is based on a sophisticated electro-hydraulically controlled drivetrain, which includes a variable center differential to control the power distribution between the front and rear wheels. In addition, a similar electro-hyrdaulically controlled differential regulates the torque split between the left and right rear wheels. Normally, the engine output is divided 31 percent to the front axle, 69 percent to the rear. This preserves the traditional rear-drive feel which has always been a Porsche hallmark. In the event the system detects wheelspin, the electronic control system modulates hydraulic valves to lock the multi-plate clutches in the center and rear differentials. In this way, engine power is diverted to the wheels with the most grip. The result is improved traction under all conditions, without requiring any special action on the part of the driver. For extreme situations, such as starting up on glare ice or climbing steep snow-covered driveways, the driver of the Porsche Carrera 4 can call up added traction by means of a switch on the center console which temporarily locks both differentials.

Superior traction, wet or dry

AWD offers superior traction under all conditions. Even on dry pavement, AWD offers benefits for a high-powered sports car. Strictly speaking, a car's acceleration is limited by the amount of force which can be transmitted by the tires to the road (in other words, the traction, or grip, of the tres). If one attempts to put more force than the maximum available grip through the area with which the tire contacts the road, the tire will break free of the road surface and spin, providing little or no traction.

But when the engine power is applied to all four wheels, the force is distributed through four tire contact patches instead of two, thus offering superior grip under dry conditions, but especially in wet and slippery conditions. AWD also offers improved stability under straight- line acceleration.

Improved stabilityand higher grip

AWD advantages are not restricted to straight-line acceleration or slippery conditions. In cornering at the limit, the Carrera 4 is ess sensitive to power changes than any two-wheel (front or rear) drive car, resulting in more usable horsepower.

3.6 LITER ENGINE

Legendary flat-6 air-cooled engine

The Carrera 4 is powered by the normally-aspirated version of Porsche's 3.6 liter engine The engine consists of a pressure-cast aluminum alloy crankcase housing a forged steel crankshaft. The connecting rods are made of forged steel, and the pistons are of forged aluminum, concepts proven on the race track for nearly three decades. The aluminum alloy cylinder heads incorporate hemnispherical combustion chambers and utilize two spark plugs per cylinder. The twin plugs grew out of Porsche's experience on the race track as well as technology transfer from high-performance aircraft engines that were in turn based on the roadgoing 911 engine. Twin plugs allow the best of both worlds-higher power output as well as cleaner combustion, with less tendency to knock. The exhaust ports are ceramic- lined to lower engine cylinder head temperatures and increase the effectiveness of the catalytic converter. Each cylinder contains a single chain-driven overhead cam, which activates the valves through solid liters.

Resonance induction

Air enters the engine through a resonance induction system, which assures optimum cylinder filling across a broad range of engine loads and speeds, and provides a wide, usable torque band.

Dry sump lubrication

The Porsche 911 engine is air-cooled by a belt-driven fan. The 911 has always used a dry sump lubrication system, common on race cars but seldom seen on road cars. Two principal advantages of dry sump systems are their decreased sensitivity to high cornering forces, which might cause ubrication problems, oil starvation and even engine damage with conventional oil pan systems, and their large oil capacity (in this case more than 12 quarts of oil circulate to help cool the engine).

BRAKE SYSTEMS

Large brakes, ABS standard

In keeping with Porsche's tradition of providing braking performance to match the high levels of acceleration possible with its products, the Carrera 4 employs front 11.73 in. (298mm) and rear 11.77 in. (299 mm) ventilated disc brakes, each with a four-piston caliper. Like every 1994 Porsche, the Carrera 4 has anti-lock brakes as standard equipment.

In brake systems, as in so many other components, Porsche's racing experience has led directly to major improvements for production cars - improvements customers can feel and use every day. Technology transfer from race track to street often results in race-proven systems finding their way directly to the assemblyline. For example, the brake system used on the legendary Type 917 race cars the early 1970s was applied to the 911 Turbo as of 1977.

The key to high-performance braking is heat management. The energy represented by the speed of the car must be converted to heat and transferred to the surrounding air as quickly as possible. Managing this heat transfer requires careful design of the mechanical parts of the brake system, as well as the bodywork and ducting of the car.

Design for optimum cooling

Porsche design parameters for improved brake system performance include the following:

• temperature-resistant engine piston alloys are used for brake caliper pistons
• brake luid is kept at a lower temperature by the large radiating surface of calipers
• wear-resistant asbestos-free brake pads provide the highest possitble resistance to fading
• use of DOT 4-200 brake fluid, with a higher wet boiling point for greater resistance to fading and extended intervals between brake fluid changes

Porsche's brake discs employ spiral-shaped internal cooling ribs, with additional half-ribs to radiate heat away from the rubbing surfaces. It takes more to duct cooling air to the brakes than simply cutting the biggest possible holes in the bodywork. Too much cooling air flow will increase drag and front-end lift Too little air flow results in overheating and altered brake bias. Porsche has found the best compromise in underbody ducting in the nose, a flexible spoiler attached to the lower suspension arms, and a deflector plate attached to the suspension to direct air through the brake splash shield. Wheel design is also a vital element of the brake cooling system. The openings between the spokes must be designed to extract hot air from under the fenders.

Brake testing in the laboratory and on the road

Porsche conducts extensive laboratory and road tests to optimize brake designs. The final testis how the brake system performs on the road. Porsche tests on famous race tracks such as the Nürburgring and Hockenheimring, and under real-world conditions such as the steep mountain roads on Mont Ventoux in southern France.

The net result of Porsche's quest for the ultimate in braking performance is that every Porsche production car is capable of extended duty on race tracks without any special modifications to the brake system. In view of such rigorous demands, it comes as no surprise that Porsche brakes provide the utmostin stopping ability under everyd ay driving conditions.

SUSPENSION AND STEERING

Wide 17-inch wheels standard

The Carrera 4 is fitted with 17-inch wheels as standard equipment. The front suspension consists of coil springs over MacPherson struts mounted on aluminum alloy lower control arms, together with a 0.83 inch (21 mm) stabilizer bar; the rear suspension employs a 0.87 inch (22 mm) stabilizer bar along with aluminum semi-trailing arms on coil springs. In addition, the rear suspension incorporates bulilt-in toe correction to provide a form of passive rear wheel steer. The Carrera 4 employs force-sensitive hydraulically assisted rack and pinion steering

PERFORMANCE

Zero to 60 mph and top speed

In terms of acceleration ability, the all-wheel-drive system ofthe Porsche Carrera 4 sacrifices nothing to the traditional rear-drive Carrera 2. The Carrera 4 accelerates to 60 mph in 5.5 seconds, and can reach a top test track speed of 158 mph. (Performance data is provided for comparison purposes only. Porsche recommends obeying all speed laws.)

SAFETY

At Porsche, safety begins with a car's driving characteristics. The dynamic behavior of Porsche sports cars is the result of advanced testing and experimentation, as well as experience on the race track. The results are uncompromising design of suspension, steering, and brakes. Safety considerations are also reflected in the comfort, excellent visibility, and ergonomically correct design of Porsche sports cars.

Highlights of Porsche's safety engineering

Safety is not a new concept at Porsche. As early as 1952, all Porsche cars were fitted with laminated safety glass windshields. In 1956, Porsche offered seat belts as an option on the 356. A 1959 race car, the Type 718, pioneered the articulated steering column which today is used on all Porsche models. In 1961, Porsche offered a shoulder belt as an option, and in the following year made three-point belts available. Racing experience led to the introduction of plastic fuel tanks,first used in the racing-only 911 R of 1967. Plastic tanks are not only impact and fire resistant, but are also impervious to corrosion. Since 1973, every Porsche 911 has been equipped with door reinforcements for increased protection in side impacts. In 1990, Porsche was the first auto manufacturer to equip all of its products with anti-lock brakes. Also in 1990, Porsche was the first manufacturer, domestic or import, to equip every car sold in the United States with driver as well as front passenger airbags as standard equipment.

Structural safety

Airbags and safety belts represent just one level of protection for the occupants, however. The car's structure is also designed for safety, with a rigid cage to surround the occupants and deformable crush zones to absorb impacts. Porsche was the first manufacturer to build car bodies using sheet steel galvanized on both sides. This not only preserves the appearance of the car and the owner's investment, but also maintains the built-in crash- worthiness of the car. Porsche is one of only two manufacturers who feels so strongly about its corrosion protection measures that it provides a full ten-year limited warranty against rust perforation. Even the paint carries a three-year limited warranty.

PORSCHE, SPORTS CARS AND THE ENVIRONMENT

Environmental responsibility

Porsche is not only pioneer in high technology and high performance, but an industry leader in environmental responsibility. This begins with building cars to last. Of all the Porsches built since 1948, it is estimated that 80 percent are still in service. Part of that longevity comes from the fully galvanized bodywork of the Porsche 911. Its durability has been a factor in maintaining Porsche's traditionally high resale values and unparalleled owner loyalty.

Efficient recycling

During development of the 1995 91 1 Carrera, the goal of recyclability of a high proportion of materials used in producing the car was given priority - and achieved. If and when a Porsche reaches the end of its useful life, labeling of various plastic components willmake it easier to reprocess parts, and will help to put plastics back into consumer products, not in landiflls. Lightweight metals, such as aluminum and magnesium, as well as steel, are easily recycled.

Performance WITH LESS pollution

Despite their high performance, Porsche cars are among the cleanest on the road. Highly effective three-way catalytic converters, oxygen sensors, and engine management systems have long been partof the Porsche pedigree. Al Porsche models are equipped with systems that fulfill the most stringent exhaust standards worldwide.

Ozone-friendly HFC-134a refrigerant

Growing concern about the possible effects of chlorofluorocarbons, including the CFC-12 refrigerants used in automotive air conditioning systems, on the earth's ozone layer led Porsche to introduce a CFC-free refrigerant, HFC-134a, beginning with its 1993 models. The higher cost of HFC-134a, and its higher salvage value, also provide a monetary recycling incentive for repair shops.

SPECIAL OPTIONS AND EUROPEAN DELIVERY

Special-order options available for all Porsches

Porsche owners who would like to further personalize their cars can take advantage of Porsche's special options program. Porsche offers a wide range of special order items to make each car uniquely individual. These include paint to match any sample color and leather to dupli licate any sample shade. Virtually every interior item may be ordered with factory-applied leather trim.

Porsches European delivery

Every Porsche may be ordered through participating U.S.dealers for European delivery This program offers an unforgettable driving experience, enabling the buyer to sample the high-speed motorways and scenic, winding secondary roads which gave birth to the Porsche legend.

WARRANTY

Broad warranty coverage

Thanks to decades of experience building solid, urable high-performance cars, Porsche's warranty coverage is among the broadest of any sports car manufacturer. Each Porsche is covered by a two-year new vehicle limited warranty with unlimited mileage, which includes the Porsche roadside assistance program. The fully galvanized body and 26-step paint and anti-corrosion process enable Porsche to warrant each car for ten years and unlimited mileage against rust perforation, protection unmatched by any other sports car manufacturer. In addition, the paintwork carries a three-year limited warranty.

Two-year parts warranty

In addition to the extensive warranty coverage of Porsche cars, Porsche also warrants parts and accessories for two years and unlimited mileage. For parts and accessories installed by authorized Porsche dealers, labor costs are also covered.

LEASING AND FINANCING

Porsche Credit Corporation offers attractive leasing, financing and balloon payment plans for new and used Porsche sports cars. The "Porsche Preferred Lease" program is available for new Porsche sports cars and for 1991-1994 pre-owned cars. The lease term can be as long as 60 months. Finance terms of up to 84 months are available. The "Porsche Options" program combines the economies of leasing with the benefits of ownership for new Porsches as well as 1990-1994 pre-owned Porsches. (Certain programs may not be available in all 50 states.)

Attractive leasing terms for new and pre-owned Porsches

These financial options allow more American drivers to enjoy the thrill of the Porsche experience, an experience which draws on Porsche's legendary heritage as the maker of both the world's finest performance automobiles and some of the most innovative and successful cars in the history of automobile racing.