A unique combination of performance and efficiency

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Eklenme Tarihi: May 16, 2013 CAR
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Stuttgart. The 918 Spyder embodies the essence of the Porsche idea: it combines pedigree motor racing technology with excellent everyday utility, and maximum performance with minimum consumption. The task faced by the development team was to create the super sports car for the next decade with a highly efficient and powerful hybrid drive. Developing the car from scratch, appropriately beginning with a sheet of white paper, allowed the team to come up with a no-compromise concept. The entire car was designed around the hybrid drive. The 918 Spyder therefore demonstrates the potential of the hybrid drive to a degree never seen before: the parallel improvement of both efficiency and performance without one being at the cost of the other. This is the idea that has made the Porsche 911 the most successful sports car in the world for 50 years. In short, the 918 Spyder will act as the gene pool for the Porsche sports cars of the future.

The 918 Spyder reveals its close links to motorsport in a variety of ways. It has been designed, developed and produced by Porsche engineers who build race cars, in cooperation with series production specialists. A great deal of insight gained from the development of Porsche race cars for the 24 hours race in Le Mans in 2014 is thus integrated into the 918 Spyder – and vice versa. The structural concept of the 918 Spyder with a rolling chassis as its basis – a basic vehicle that can be driven even without a body – is race car tradition at Porsche. The concept of the V8 engine originates from the LMP2 RS Spyder race car. The load-bearing structures, the monocoque and subframe, are made of carbon fibre reinforced polymer. Porsche has many years of experience with this high-strength, lightweight construction material and has again achieved top results with the development of the series production 918 Spyder. Many parts of the super sports car come from manufacturers who have a proven record as suppliers for motorsport vehicles.

Hybrid drive brings advantages in terms of driving dynamics
A key message of the 918 Spyder is that the hybrid drive from Porsche is a plus for no-compromise driving dynamics. Drivers can experience this thanks to the unique all-wheel drive concept with a combination of combustion engine and electric motor on the rear axle and the second electric motor on the front axle. It is based on knowledge gained by Porsche during motor races with the successful 911 GT3 R Hybrid. Due to the additional, individually controllable front drive, new driving strategies for extremely high, safe cornering speeds can be implemented, especially for bends. Furthermore, the advanced “boost” strategy manages the energy of the electric drive so intelligently that, for every sprint with maximum acceleration, the full power of the 918 Spyder can be tapped into by simply pressing the accelerator down fully. In short, the 918 Spyder allows even drivers without motorsport training to experience the potential of advanced longitudinal and transverse dynamics.

The Porsche 918 Spyder also has the potential to break many records. The current lap time for the North Loop of the Nürburgring is 7:14 minutes. This time was achieved in the presence of international journalists during test drives in September 2012 – more than a year before start of production. The 918 Spyder prototype was therefore approximately 20 seconds quicker than the Porsche Carrera GT. More test drives on the Nürburgring North Loop will follow. An even more important factor is that the 918 Spyder surpasses previous models and competitors by far in its efficiency as well. As a plug-in hybrid vehicle, it systematically combines the dynamic performance of a racing machine with over 880 hp and low NEDC fuel consumption, which at about three litres fuel per 100 km is better than that of most small cars today. To sum it up: maximum driving fun with minimal fuel consumption.

Carbon monocoque guarantees lightweight design with a low centre of gravity
The 918 Spyder utilizes the best state-of-the-art technologies, taken straight from motor racing, to achieve its top performance. The entire load-bearing structure is made of carbon fibre reinforced polymer (CFRP) for extreme torsional rigidity. Additional crash elements at the front and rear absorb and reduce the energy of a collision. The car’s unladen weight of approximately 1,640 kg (“Weissach” package), an excellent low weight for a hybrid vehicle of this performance class, is largely attributable to this concept. The drivetrain components and all components weighing over 50 kg are located as low and as centrally as possible within the vehicle. This results in a slightly rear end biased axle load distribution of 57 per cent on the rear axle and 43 per cent on the front axle, combined with an extremely low centre of gravity at approximately the height of the wheel hubs, which is ideal for driving dynamics. The central and low position of the traction battery directly behind the driver not only supports efforts to concentrate masses and lower the centre of gravity; it also provides the best temperature conditions for optimum battery power capacity.

Chassis with race car genes and rear-axle steering
The multi-link chassis of the Porsche 918 Spyder is inspired by motorsport design, complemented by additional systems such as the PASM adaptive shock-absorber system and rear-axle steering. Basically, this incorporates an electro-mechanical adjustment system at each rear wheel. The adjustment is speed-sensitive and executes steering angles of up to three degrees in each direction. The rear axle can therefore be steered in the same direction as the front wheels or in opposition to them. At low speeds, the system steers the rear wheels in a direction opposite to that of the front wheels. This makes cornering even more direct, faster and more precise, and it reduces the turning circle. At higher speeds, the system steers the rear wheels in the same direction as the front wheels. This significantly improves the stability of the rear end when changing lanes quickly. The result is very secure and stable handling.

Porsche Active Aerodynamic (PAA) for different driving modes
Porsche Active Aerodynamic (PAA), a system of adjustable aerodynamic elements, ensures unique and variable aerodynamics; its layout is automatically varied over three modes ranging from optimal efficiency to maximum downforce and is tuned to the operating modes of the hybrid drive system. In “Race” mode, the retractable rear wing is set to a steep angle to generate high downforce at the rear axle. The spoiler positioned between the two wing supports near the trailing edge of the airflow also extends. In addition, two adjustable air flaps are opened in the underfloor in front of the front axle, and they direct a portion of the air into the diffuser channels of the underbody structure. This also produces a “ground effect” at the front axle.

In “Sport” mode, the aerodynamic control system reduces the attack angle of the rear wing somewhat, which enables a higher top speed. The spoiler remains extended. The aerodynamic flaps in the underfloor area close, which also reduces aerodynamic drag and increases attainable vehicle speeds. In “E” mode, the control is configured entirely for low aerodynamic drag; the rear wing and spoiler are retracted and the underfloor flaps are closed.

Adjustable air inlets under the main headlights round off the adaptive aerodynamic system. When the vehicle is stationary and in “Race” and “Sport” mode, they are opened for maximum cooling air intake. In “E-Power” and “Hybrid” modes, they close immediately after the car is driven off in order to keep aerodynamic drag to a minimum. They are not opened until the car reaches speeds of approximately 130 km/h or when cooling requirements are higher.

From comfortable to race-ready: five modes for three motors
The core of the 918 Spyder concept is its distribution of propulsive power among the three power units; their cooperation is controlled by an intelligent management system. To best exploit these different approaches, the Porsche developers defined five operating modes that can be activated via a “map switch” on the steering wheel, just like in motorsport cars. On the basis of this pre-selection, the 918 Spyder applies the most suitable operating and boost strategy without driver intervention, thus allowing the driver to concentrate fully on the road.

Quiet and elegant: “E-Power”
When the vehicle is started up, the “E-Power” mode is the default operating mode as long as the battery is sufficiently charged. In ideal conditions, the 918 Spyder can cover over 30 kilometres on purely electric power. Even in pure electric mode, the 918 Spyder accelerates from 0 to 100 km/h in less than seven seconds and can reach speeds of up to 150 km/h. In this mode, the combustion engine is only used when needed. If the battery’s charge state drops 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 alternately with a focus on maximum efficiency and minimum fuel consumption. The use of individual drive components is modified as a function of the current driving situation and the desired performance. The Hybrid mode is typically used for a fuel economy-oriented driving style.

Sporty and dynamic: “Sport Hybrid”
In more dynamic situations, the 918 Spyder selects the “Sport Hybrid” mode for its power sources. The combustion engine now operates continuously and provides the main propulsive force. In addition, the electric motors provide support in the form of electric boosting or when the operating point of the combustion engine can be optimised for greater efficiency. The focus of this mode is on performance and a sporty driving style at top speed.

For fast laps: “Race Hybrid”
“Race Hybrid” is the mode for maximum performance and an especially sporty driving style. The combustion engine is chiefly used under high load, and charges the battery when the driver is not utilising its maximum output. Again, the electric motors provide additional support in the form of boosting. Furthermore, the gear-shifting programme of the PDK is set up for even sportier driving. The electric motors are used up to the maximum power output limit to deliver the best possible performance for the race track. In this mode, the battery charge state is not kept constant, rather it fluctuates over the entire charge range. In contrast to Sport Hybrid mode, the electric motors run at their maximum power output limit for a short time for better boosting. This increased output is balanced by the combustion engine charging the battery more intensively. Electric power is thus available even with several very fast laps.

For pole position: “Hot Lap”
The “Hot Lap” button in the middle of the map switch releases the final reserves of the 918 Spyder 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 race car’s eight cylinder engine
The main source of propulsion is the 4.6-litre, eight cylinder engine that produces 608 hp of power. The engine is derived directly from the power unit of the successful RS Spyder, which explains why it can deliver engine speeds of up to 9,150 rpm. Like the race engine of the RS Spyder, the 918 Spyder power unit features dry-sump lubrication with a separate oil tank and oil extraction. To save weight, components such as the oil tank, the air filter box integrated into the subframe and the air induction are made of carbon fibre reinforced polymer. Further extensive lightweight design measures have resulted in such features as titanium connecting rods, thin-wall, low-pressure casting on the crank case and the cylinder heads, a high-strength, lightweight steel crankshaft with 180 degrees crankpin offset and the extremely thin-walled alloy steel/nickel exhaust system. Striking features of the V8 are that it no longer supports any auxiliary systems, there are no external belt drives and the engine is therefore particularly compact. Weight and performance optimisations achieve a power output per litre of approx. 132 hp/l – the highest power output per litre of a Porsche naturally aspirated engine – which is significantly higher than that of the Carrera GT (106 hp/l) and outstanding for a naturally aspirated engine.

Unique race car design heritage: top pipes
It isn’t just this engine’s performance but also the sound it makes that stokes the emotionality of the 918 Spyder. This is attributable first and foremost to the so-called top pipes: the tailpipes terminate in the upper part of the rear end immediately above the engine. No other production vehicle uses this solution. The top pipes’ greatest benefit is optimal heat removal, because the hot exhaust gases are released via the shortest possible route, and exhaust gas back pressure remains low. This design requires a new thermodynamic air chan