Wednesday, May 2, 2012

Porsche 918 Spyder Hybrid prototype

Porsche 918 Spyder Hybrid prototype side front
Porsche 918 Spyder Hybrid prototype side back
Porsche 918 Spyder Hybrid prototype side interior
Porsche 918 Spyder Hybrid prototype frontPorsche 918 Spyder Hybrid prototype side
Porsche 918 Spyder Hybrid prototype upPorsche 918 Spyder Hybrid prototype interior

The 918 Spyder prototype combines high-tech racing features and electro-mobility to offer a fascinating range of qualities: An emission level of just 70 grams CO2 per kilometre on fuel consumption of three litres/100 kilometres (equal to 94 mpg imp) truly outstanding even for an ultra-compact city car, on the one hand, combined with the performance of a super sports car and acceleration from a standstill to 100 km/h in just under 3.2 seconds, top speed of 320 km/h (198 mph) plus, and a lap time on the Nordschleife of Nürburgring in less than 7:30 minutes, faster than even the Porsche Carrera GT, on the other.

Evolution meets emotion: The technology behind tomorrow’s super sports car

The future is taking shape: with more than half of its development time completed, the Porsche 918 Spyder is firmly on course to become the super sports car of tomorrow. As a plug-in hybrid vehicle, it combines a high-performance combustion engine with cutting-edge electric motors to deliver performance that is beyond extraordinary: the best of both worlds endows the 918 with the dynamics of a racing car packing more than 770 hp of power accompanied by fuel consumption, which at approximately three liters per 100 kilometres, is less than that of most modern compact cars. Moreover, Porsche is breaking more new ground with the technology demonstrator with spectacular solutions such as the full carbon fiber reinforced plastic (CFRP) body, fully adaptive aerodynamics, adaptive rear-axle steering and the upward-venting “top pipes” exhaust system. In the process, the 918 Spyder is offering a glimpse of what Porsche Intelligent Performance may be capable of in the future.

The 918 Spyder has been designed as a super sports car and the legitimate successor to the Carrera GT. As such, the first goal was obvious: improving yet again on the Carrera GT’s performance. As far as is currently known, the 918 Spyder will be significantly faster – both in terms of acceleration and also performance on the racing circuit: less than three seconds from zero to 100 km/h (Carrera GT: 3.9 seconds) and less than 7:22 minutes on the Nürburgring Nordschleife (Carrera GT: 7:32 minutes) is an unmistakable statement. However, the uniqueness of the 918 Spyder is best represented by the union of outstanding performance with a level of efficiency never seen before in the super sports car sector. Fuel consumption of approximately three liters per 100 kilometres and an electric range in excess of 25 kilometres are unprecedented.

From comfortable to ready to race: five modes for three motors

The core of the 918 Spyder concept is the distribution of propulsive power across three power units, collaboration between which is controlled by an intelligent management system using five pre-selectable modes. This operating strategy is a core competency of the 918 Spyder. It takes the best possible account of the different requirements between an efficiency-oriented driving profile on the one hand and maximum performance on the other. In order to make the best possible use of these different approaches, the Porsche developers defined a total of five operating modes that can be activated via a “map switch” in the steering wheel, just like in motor sports cars.

Quiet and elegant: “E-Power”

When the vehicle is started up, the “E-Power” is the default operating mode as long as the battery is sufficiently charged. In ideal conditions, the 918 Spyder can cover more than 25 kilometres on purely electric power. In this mode, the combustion engine is only used when needed: maximum engine power is available at a moment’s notice by means of the kick-down function. If the charge state of the battery falls below a set minimum value, the vehicle automatically switches to hybrid mode.

Efficient and comfortable: “hybrid”

In “hybrid” mode, the electric motors and combustion engine work together with the focus on maximum efficiency and minimum fuel consumption. The use of the individual drive components adapts depending on the current driving situation and the desired performance. The hybrid mode is typically used for moderate, consumption- oriented driving styles, e.g. in city traffic.

Sporty and dynamic: “Sport Hybrid”

In more dynamic situations, the 918 Spyder selects the “Sport Hybrid” mode for its motors. The combustion engine is now in constant operation and provides the main propulsive force. In addition, the electric motors provide support in the form of an electric boost when the driver demands higher output, or if there is scope to optimize the operating point of the combustion engine for greater efficiency. The focus of this mode is on performance and a sporty driving style.

For fast laps: “Race Hybrid”

“Race Hybrid” is the mode for the highest possible performance and especially sporty driving style. The combustion engine is chiefly used under high load, and charges the battery when the driver is not utilising the maximum output. The electric motors provide additional support as necessary in the form of a boost when the driver requires even more power. The electric motors are used up to the maximum power output limit in order to provide the best possible performance for the race track. In this mode, the battery charge state is not kept constant, but instead fluctuates across the entire charge range. In contrast to Sport Hybrid mode, the electric motors run at their maximum power output limits for a short time, thus ensuring better boosting. This increased output is balanced out by the combustion engine charging the battery more powerfully.

For pole position: “Hot Lap”

The “Hot Lap” button in the middle of the map switch releases the 918 Spyder’s last reserves and can only be activated in “Race Hybrid” mode. Similar to a qualification mode, this pushes the traction battery to its maximum power output limits for a few fast laps. This mode uses all of the available energy in the battery.

Main propulsion: the racing car’s eight cylinder engine

The main source of propulsion is the 4.6-liter, eight cylinder engine delivering more than 570 hp of power, which was directly derived from the power unit in the successful RS Spyder and explains why it delivers engine speeds of up to 9,000 rpm. Like the RS Spyder’s racing engine, the 918 Spyder power unit features dry-sump lubrication with a separate oil tank and oil extraction. In order to save weight, the four extraction pumps are made of plastic. Further extensive lightweight design measures resulted in, for example, titanium connecting rods, thin-wall, low-pressure casting on the crank case and the cylinder heads, a high-strength, light-weight steel crankshaft and the extremely thin-walled, alloy steel exhaust system. The result of the weight and performance optimizations is a power output per liter of approx. 125 hp/l, which is significantly higher than that of the Carrera GT (106 hp/l) and outstanding for a naturally aspirated engine.

Lithium-ion battery with plug-in charging system

The electric energy for the electric motors is stored by a liquid-cooled lithium-ion battery comprising 312 individual cells with an energy content of approximately seven kilowatt hours. The battery of the 918 Spyder has a performance-oriented design in terms of both power charging and output in order to fulfil the performance requirements of the electric motor. The power capacity and the operating life of the lithium-ion traction battery are dependent on several factors, including thermal conditions. That is why the 918 Spyder’s battery is liquid-cooled by a dedicated cooling circuit.

To supply it with energy, Porsche developed a new system with a plug-in charging interface and multiplied recuperation potential. The plug-in interface in the B-column on the front passenger side enables the storage battery to be connected directly with the home mains supply and charged. The charging interface is standardized for the country of purchase. The charger is located close to the traction battery. It converts the alternating current of the mains supply into direct current with a maximum charge output of 3.6 kW. For example, using the charging cable supplied with it, the battery can be charged within four hours from a ten ampere rated, fused power socket on the German 230 Volt mains supply. A compact charging station is also supplied as standard with the 918 Spyder. This can be installed permanently in the driver’s garage. It permits rapid and convenient charging within approximately two hours, irrespective of regional conditions.

A new super sports car for a new decade

The 918 Spyder continues the super sports car line in Porsche history; as technology demonstrators, the driving force behind emotion and evolution alike and the ultimate sports cars of their decade: the Carrera GTS, the first Porsche Turbo, the 959, the 911 GT1, the Carrera GT. More than any of its predecessors, the 918 Spyder is providing a critical impetus to developing the technologies for future vehicle concepts.

Porsche Press

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