coursework on porsche 918 spyder

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    A REPORT ON EFFECTS OF CAFFEINE

    A project submitted in partial fulfilment of the award of grade points in

    Automobile Engineering

    By

    N.Vinay

    (1210813239)

    (3/4 B.tech ,MECHANICAL ENGINEERING)

    Under the extreme guidance of

    K. Mahendra Babu

    Assistant Professor

    Department of Mechanical

    GITAM Institute of Technology

    GITAM University

    Department of Mechanical

    GITAM Institute of Technology

    GITAM University

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    VISHAKAPATNAM-530045

    Coursework on Porsche 918

    Spyder

    Introduction:

    The Porsche 918 Spyder is a mid-engined plug-in hybrid

    sports car designed by Porsche. The Spyder is powered

    by a naturally-aspirated 4.6 litre V8 engine. The 918

    Spyder is a limited edition Hyper car, with 918 units

    manufactured and sold as a 2014 model year. This

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    model was designed by Michael Mauer.

    Production began on September 18, 2013, with

    deliveries initially scheduled to begin in December 2013.

    The starting price was US$847,000.The country with

    the most orders was the United States with 297 units.

    Production ended in June 2015.

    Specifications:

    Price

    Base price $847,015 (CAD)

    Engine

    Type V8 4.6 litres

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    Power 608 HP @ 8,700 rpm (453 kW)

    Torque 398 lb·ft @ 6,700 rpm (540 N-m)

    Induction Atmospheric

    Power to weight ratio 397.3 W/kg

    Bore 95 mm

    Stroke 81 mm

    Fuel type Premium

    CO₂ emissions 1,440 kg/year

    Electric engine

    Power 286 hp @ 6,500 rpm (213 kW)

    Torque N/A

    Battery type Lithium-ion (Li-ion)

    Energy 6 kWh

    Voltage 385 V

    Charging time

    • 120V, 10A: N/A

    • 240V, 15A: 4.0h

    • 400V : N/A

    Cooling Liquid

    Drivetrain structure N/A

    Hybrid system

    descriptionN/A

    Transmission 7-speed automatic

    Drivetrain AWD

    Vehicle type / Category

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    Vehicle type Roadster

    CategoryHybrid / Plug-in Hybrid, Sports Car

    over $100,000

    Assembly Stuttgart, DE

    Generation 1

    What's new New model

    Fuel efficiency / Autonomy

    Only Gasoline 100KM/11Lit

    Both Gasoline and

    Electric100KM/3.5Lit

    Autonomy 30 km /gallon

    Tires / Suspension / Brakes / Safety

    Steering

    rack and pinion, electrical variable

    assist

    Traction control yes

    Stability control yes

    Seat belts 2

    Airbags 6

    Front suspension independent, short/long arm

    Rear suspension independent, multi-link

    Front brakes disc (ABS)

    Rear brakes disc (ABS)

    Front tires P265/35ZR20

    Rear tires P325/30ZR21

    Dimensions / Weight

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    Length 4,643 mm (183″)

    Width 2,053 mm (81″, including mirrors)

    Height 1,167 mm (46″)

    Wheelbase 2,730 mm (107″)

    Front track 1,664 mm (66″)

    Rear track 1,612 mm (63″)

    Weight 1,678 kg (3,699 lbs)

    Weight distribution

    front-rear43% - 57%

    Capacities

    Passengers 2

    Fuel tank 70 Litres

    Performance

    0-60mph  2.5 s0-124mph  7.3 s

    0-186mph  20.9s

    Top speed 325 km/h

    Braking distance 60-0mph in

    94 feet

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    Chassis

    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 fiber 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 3,715 lbs. (3,616 lbs. with “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

    110 lbs. 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 percent on the rear axle and 43 percent on the

    front axle, combined with an extremely low center 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 center of gravity; it also

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    provides the best temperature conditions for optimum battery

    power capacity.

    Carbon Fibre Monocoque

    A rigid and light chassis is an essential component to any high

    performance automobile. These attributes better equip a racing

    car to achieve its goal of winning races. A rigid and light chassis

    allows for optimal acceleration and braking, and predictablehandling. One type of innovative and high performance chassis

    designs is the carbon fiber monocoque. The term “monocoque”

    is a French word meaning “single

    shell.” This describes the monocoque as a stressed outer

    surface in which the load is distributed. This kind of design has

    been applied to the structures of cars, boats, and airplanes. Inthe case of race cars, a carbon fiber monocoque is a carbon

    fiber tub that is used as a chassis. Many high performance cars

    use this design. A racing car utilizes many essential

    characteristics in order to perform in extreme conditions.

    Racing cars are designed to be lightweight, rigid in torsional

    stress, have effective suspension, and have a powerful engine.The carbon fiber monocoque optimizes the characteristics of

    light weight and high rigidity and, due to these factors, is

    important to the car racing world because it is currently the

    lightest and stiffest chassis technology available.

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     The carbon fiber monocoque is a continuous surface forming

    the chassis. Carbon fiber sheets are layered into an outer shell.

    This is known as a stressed-skin design. In a stressed-skin

    structure, shearing forces are carried through the sheets that

    form the planes. This is similar to how a diagonally triangulated

    tube in a space frame works. A carbon fiber monocoque is

    hollow on the inside and has an opening to form the driver’s cell

    or cockpit. There is also an open area in which the engine is

    mounted. This design allows for an extremely stiff and

    lightweight chassis.

    Unlike the steel space frame chassis in figure 3, this is a

    carbon fiber monocoque. The entire monocoque chassis is a

    continuous surface formed around where the driver will sit. The

    entire surface serves as a structural component in the vehicle.A design like this takes advantage of carbon fiber’s material

    properties allowing for a stronger and lighter chassis. While

    both this design and the space frame are light and strong, a

    carbon fiber monocoque is lighter and stiffer than a comparable

    space frame.

    While the main advantages of a carbon fiber monocoque in

    race cars are in the form of faster lap times, they have also

    made racing much safer for drivers. Carbon fiber monocoques

    form a very strong safety cell around the driver. This ensures

    the driver will not be crushed by a collapsing chassis in the

    event of a crash. Carbon fiber monocoques helped make

    Formula 1 more ethical for the drivers for which death was not

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    uncommon. Not a single Formula 1 driver has died since1994,

    and the rate of deaths dropped dramatically after the

    introduction of the carbon fiber monocoque [21]. Due to the

    nature of carbon fiber, a driver that is fully enclosed by a strong

    chassis will also be protected from any objects that might be

    trying to penetrate into the driver’s cell. The enclosure is

    important to protect a driver from other car components that will

    break during a crash. This is an advantage over a space frame

    which only has thin, lightweight bodywork covering the gaps

    between the steel tubes which is less resistant to intruding

    object [22]. A testament to this was at Monza in 1981 when

    John Watson crashed his MP4/1 into a wall at 140 miles per

    hour. Watson walked away from the crash [1]. Carbon fiber

    monocoques are important to crash safety in racing to this day.

    Suspension

    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

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    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 Suspension Management

    Optional PASM, the electronic damping control system, suits

    the new Boxster models down to the ground. PASM actively

    and continuously regulates the damping force for each wheel

    according to the road conditions and driving style. In addition,

    the suspension is lowered by 10 mm.

    Forward thrust | Chassis The driver can select between twodifferent modes: ‘Normal’ which is a blend of performance and

    comfort, and ‘Sport’ where the setup is much firmer. Depending

    on the mode selected, therefore, PASM can be both sportier

    and more comfortable than the standard chassis. The PASM

    control unit evaluates the driving conditions and modifies the

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    damping force on each of the wheels in accordance with the

    selected mode.

    Sensors record the body movements that accompany powerfulacceleration, braking or uneven road surfaces. This enables

    intelligent adaptation of damper stiffness for the selected mode,

    optimising contact between each individual tyre and the road

    and reducing pitch.

    Porsche Active AerodynamicPorsche 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 angleto 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" atthe 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

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    “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.

    Braking System

    High-performance hybrid brake system with adaptive

    recuperation; internally ventilated and perforated front ceramic

    brake discs (PCCB), 16 in. in diameter and 1.4 in. thick; rear

    discs 15.4 in diameter and 1.3 in. thick.

    As like many other hybrid cars this also uses regenerative

    braking system to charge the batteries.

    Drive Train

    The V8 engine is coupled to the hybrid module, since the 918

    Spyder is designed as a parallel hybrid like the current hybrid

    models from Porsche. Essentially, the hybrid module comprises

    a 115 kW electric motor and a decoupler that serves as the

    connection with the combustion engine. Because of its parallel

    hybrid configuration, the 918 Spyder can be powered at the

    rear axle either individually by the combustion engine or electric

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    motor or via both drives jointly. As is typical for a Porsche super

    sports car, the power pack in the 918 Spyder has been placed

    in front of the rear axle, and does not have any direct

    mechanical connection to the front axle.

    On the front axle, there is another independent electric motor

    with an output of approximately 95 kW. The front electric drive

    unit drives the wheels at a fixed ratio. A decoupler decouples

    the electric motor at high speeds to prevent the motor from

    over-revving. Drive torque is independently controlled for eachaxle. This makes for very responsive all-wheel drive

    functionality that offers great potential in terms of traction and

    driving dynamics.

    The Weissach package

    For very performance-oriented customers of the 918 Spyder,

    Porsche offers the “Weissach" package. These modified super

    sports cars can be recognized at first glance by special colors

    and designs that are based on legendary Porsche race cars.

    The roof, rear wings, rear-view mirrors and frames of the

    windscreen are made of visible carbon. Parts of the interior are

    upholstered with Alcantara instead of leather, and visible

    carbon replaces much of the aluminum. Sound insulation has

    been reduced. The emphasis on performance is not just visual:

    very lightweight magnesium wheels reduce unsprung masses;

    gross weight was reduced by about 77 lbs. The benefits are

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    experienced in further improved dynamic performance. Other

    references from motorsport are six-point seatbelts for driver and

    front passenger, optional film-coating instead of body paint, as

    well as additional aerodynamic body parts in visible carbon.

    Cockpit

    The driver is the focus of all technology in the future Porsche

    super sports car. A cockpit was created for the driver that is

    typical of the brand and pioneering in its clarity. It is partitioned

    into two basic areas. First, there are the controls that are

    important for driving, which are grouped around the

    multifunction steering wheel, combined with driver information

    displayed on three large round instruments. Second, there is

    the infotainment block that is housed in the lifted center

    console, which was introduced in the Carrera GT. Control

    functions, e.g. for the automatic climate control system, wing

    adjustment, lighting and Porsche Communication Management

    (PCM), including a Burmester high-end sound system, can be

    intuitively operated by multitouch with a new type of black panel

    technology.

    Engine

    The main source of propulsion is the 4.6-liter, 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

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    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 fiber 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 optimizations achieve a power output per liter of

    approx. 133 hp/l – the highest power output per liter 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.

    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 immediatelyabove 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 channeling

    concept. With the HSI engine, the hot side is located inside the

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    cylinder V, the intake channels are on the outside. There is

    another benefit as well: the engine compartment remains

    cooler. This is especially beneficial to the lithium-ion traction

    battery, as it provides optimum performance at temperatures

    between 68 and 104 degrees Fahrenheit. Consequently, less

    energy needs to be used for active cooling of the battery.

    Battery

    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 about seven kilowatt hours. The battery of

    the 918 Spyder has a performance-oriented design in terms of

    both power charging and output, so that it can fulfil the

    performance requirements of the electric motor. The power

    capacity and the operating life of the lithium-ion traction battery

    depend on several factors, including thermal conditions. That is

    why the battery of the 918 Spyder is liquid-cooled by a

    dedicated cooling circuit. The global warranty period for the

    traction battery is seven years.

    To supply it with energy, Porsche developed a new system with

    a plug-in vehicle charge port and improved recuperation

    potential. This vehicle charge port in the B-pillar on the front

    passenger side lets users connect the storage battery to an

    electrical supply at home to charge it. The charge port is

    standardized for the country of purchase. The on-board charger

    is located close to the traction battery. It converts the alternating

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    current of the household electric supply into direct current with

    a maximum charge output of 3.6 kW. Using the supplied

    Porsche Universal Charger (AC), the traction battery can be

    charged with a conventional wall plug in seven hours from a ten

    ampere rated, fused power socket a US 110 Volt household

    electrical supply, for example. Furthermore, the Porsche

    Universal Charger (AC) can be installed at home in the garage

    using the Charging Dock. It enables rapid and convenient

    charging within approximately two hours, irrespective of

    regional conditions. The Porsche Speed Charging Station (DC)

    is available as an optional extra. It can fully charge the high-

    voltage battery of the 918 Spyder in just 25 minutes.

    Porsche Torque Vectoring (PTV)

    This optional system for increasing dynamic performance andstability varies the distribution of torque to the rear wheels and

    includes a locking rear differential.

    When the car is driven assertively into a corner, moderate brake

    pressure is applied to the inside rear wheel. Consequently, an

    additional rotational pulse (yaw movement) is induced around

    the vehicle’s vertical axis in the direction of the turn. This results

    in a direct and sporty steering action as the car enters the

    corner.

    At low and medium vehicle speeds, PTV significantly increases

    agility and steering precision. At high speeds and when

    accelerating out of corners, the rear differential lock ensures

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    greater driving stability and traction on road surfaces with

    varying grip, including wet and wintery conditions with cold

    weather tires.

    The results are remarkable stability, optimum traction and

    excellent cornering dynamics at all speeds, coupled with

    precise steering and stable load transfer characteristics through

    every twist and turn of your journey.

    Porsche Stability Management (PSM)

    Porsche Stability Management (PSM) is fitted as standard. This

    system automatically maintains stability and traction even at the

    limits of dynamic driving performance. Sensors continuously

    monitor the direction, speed, yaw velocity and lateral

    acceleration of the car. Using this information, PSM is able to

    calculate the actual direction of travel at any given moment. If

    the car begins to oversteer or understeer, PSM applies

    selective braking on individual wheels in order to restore

    stability.

    When accelerating on wet or low-grip road surfaces, PSM

    improves traction – as well as agility, control and safety – usingthe automatic brake differential (ABD) and anti-slip regulation

    (ASR). Integrated ABS is designed to minimise braking

    distances.

    Transmission

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    Porsche Doppelkupplung (PDK)

    PDK offers extremely fast gear changes with no interruption in

    the flow of power, improved acceleration over the manual

    transmission, very short response times, reduced fuel

    consumption and a distinct increase in comfort.

    PDK is essentially two gearboxes in one, thus requiring two

    clutches. This double clutch transmission provides an

    alternating, non-positive connection between the two halfgearboxes and the engine by means of two separate input

    shafts. The flow of power from the engine is transmitted through

    one half gearbox and one clutch at a time, while the next gear

    is preselected in the second half gearbox. Therefore, during a

    gear change, one clutch simply opens and the other closes

    simultaneously, enabling gear changes to take place withinmilliseconds.

    With the SPORT button selected, the full advantages of PDK

    are brought into play: a more immediate response to throttle

    inputs, relatively short shift times and swift throttle-blip

    downshifts on overrun, such as when braking into a corner, and

    always accompanied by an emotive engine sound.

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