Download - 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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