Mercedes-Benz SLS AMG: high-tech and fascination
The new 'Gullwing' from Mercedes-Benz Comprehensive review
Stuttgart/Affalterbach – For the first time in the company's history
stretching back over 40 years, the Mercedes-Benz performance brand
is presenting a vehicle developed in-house, the Mercedes-Benz SLS AMG.
The super sports car serves up an exciting proposition with its unique
technology package: aluminium spaceframe body with gullwing doors,
AMG 6.3-litre V8 front-mid engine developing 420 kW/571 hp peak output
and dry sump lubrication, seven-speed dual-clutch transmission in a
transaxle configuration and sports suspension with aluminium double
wishbones. The ideal front/rear weight distribution of 48 to 52 percent
and the vehicle's low centre of gravity are testimony to the uncompromising
sports car concept.
"Mercedes-Benz is presenting an exhilarating super sports car in the guise of the
new SLS AMG, which is bound to set the pulses of all car enthusiasts racing that
extra bit faster. The SLS AMG is emotion pure and simple for the Mercedes-Benz
brand and is set to become one of the most alluring sports cars of our era", says
Dr. Dieter Zetsche, Chairman of the Board of Management of Daimler AG and
Head of Mercedes-Benz Cars.
"Our customers will experience with the SLS AMG the expertise of our sports car
manufacturer Mercedes-AMG, built up over 40 years of motor racing, along with
the kind of scintillating design that only a top athlete from the Mercedes-Benz
stable can offer", says Volker Mornhinweg, Chairman of Mercedes-AMG GmbH.
The new Mercedes-Benz SLS AMG offers purist, distinctive styling, superior
driving dynamics and hallmark Mercedes everyday practicality and safety. During
the development of the new 'Gullwing', the AMG developers placed their trust in
the valuable know-how of the specialists from the Mercedes Technology Center
(MTC) in Sindelfingen. The aim of this joint development was to turn the SLS AMG
'Gullwing' into the perfect synthesis of the strengths of the Mercedes-Benz and
AMG brands.
Consistent lightweight design thanks to aluminiumThe radical design as a highly talented dynamic super sports car with its lowslung
front-mid engine set well back also feeds through into the proportions as
well as the optimised lightweight body concept: for the first time, Mercedes-Benz
and AMG are presenting a car with an aluminium chassis and body. Compared with
the traditional steel design, this results in a significant weight saving, clearly
illustrated in the planned DIN kerb weight of 1620 kilograms excluding driver.
The newly developed bodyshell comprises an aluminium spaceframe. This
exclusive design combines intelligent lightweight design with outstanding
strength – thus delivering superlative driving dynamics. Naturally, the
aluminium spaceframe meets all the requirements in terms of passive safety and
the hallmark Mercedes-Benz body quality that applies to any car sporting the
Mercedes-Benz star. Despite the low sitting position in typical sports car fashion,
the wide-opening gullwing doors make it easy to get in and out of the vehicle.
Fine-tuned AMG 6.3-litre V8 engine developing 420 kW/571 hpThe fine-tuned AMG 6.3-litre V8 engine achieves a peak output of 420 kW/571 hp
at 6800 rpm, thus turning the SLS AMG into one of the most powerful sports cars
in its segment. A power-to-weight ratio of 2.84 kg/hp comes courtesy of the low
vehicle weight. The eight-cylinder naturally-aspirated engine delivers maximum
torque of 650 Nm at 4750 rpm. The 'Gullwing' accelerates from 0 to 100 km/h
in 3.8 seconds, before going on to a top speed of 315 km/h (all figures are
provisional). Bearing the internal designation M159, the V8 high-revving engine
with its displacement of 6208 cubic centimetres has been thoroughly
reengineered compared with the M156 entry-level engine and boasts all the
hallmarks of powerful racing engines.
The principal measures in increasing output include the all-new intake system,
the reworked valve train and camshafts, the use of flow-optimised tubular steel
headers and the dethrottling of the exhaust system. This results in much better
cylinder charging, which feeds through into an increase in output to 420 kW/571
hp with maximum torque of 650 Nm. The eight-cylinder engine responds swiftly
to movements of the accelerator pedal, demonstrating much more
pronounced high-revving flexibility across the entire rev range. The switch to dry
sump lubrication also translates into a much lower position of the engine in the
vehicle. And lowering the vehicle's centre of gravity has also paved the way for
high lateral acceleration and exhilarating driving dynamics.
Perfect synthesis of lightweight design and strengthThe use of high-strength components compensates for the increased engine load
associated with the higher output. Forged pistons, a reinforced crankshaft bearing,
optimised crankcase structure, along with improved lubrication thanks to an
on-demand high-performance oil pump ensure optimum durability.
Despite these higher loads, the engine weight for the M159 has been further
reduced. The forged pistons as oscillating masses play a particularly valuable role
in this respect. Thanks to targeted weight optimisation, the weight of the engine
has been reduced further, resulting in a kerb weight of 206 kilograms and, in
turn, a power-to-weight ratio of 0.36 kg/hp. The AMG 6.3-litre V8 engine thus
delivers the best figure by far compared with its competitors.
Sophisticated catalytic converter technology enables current and future exhaust
emission standards such as EU 5, LEV 2 and ULEV to be met. The frictionoptimised
twin-wire-arc-sprayed (TWAS) coating on the cylinder walls – a process
that remains exclusive to AMG – also reduces fuel consumption, as does the
on-demand, map-optimised oil supply along with the regulated generator
management. Thanks to the targeted use of efficiency-enhancing measures,
fuel consumption for the SLS AMG is around 13 litres of Super Plus per
100 kilometres (NEDC combined, provisional figure).
Dual-clutch transmission with transaxle configuration and torque tubeThe AMG 6.3-litre V8 engine delivers its abundant power via an ultra-light
carbon-fibre driveshaft at the rear axle – similar to the set-up used on the
DTM C-Class racing touring car. The transmission is mounted at the rear
(transaxle principle) and is connected to the engine housing via a torque tube.
A carbon-fibre shaft rotates at engine speed in the torque tube. The advantages
of this sophisticated solution are associated with the rigid link between the engine
and transmission and, in turn, the optimum support for the forces and torque
generated. A new AMG dual-clutch transmission with seven gears takes care of
power transfer. The transmission boasts fast gear changes with no loss of tractive
force. The driver has a choice of four different driving modes, ranging from
comfortable to extremely sporty, as well as a RACE START function. Optimum
traction comes courtesy of the mechanical differential lock, which is integrated
in the compact transmission casing.
The chosen solution with a front-mid engine plus transaxle configuration ensures
an ideal front/rear weight distribution of 48 to 52 percent. Mounting the engine
behind the front axle has created the ideal conditions for consummate driving
dynamics with precise steering, first-class agility, low inertia with spontaneous
directional changes and outstanding traction. The suspension technology is
also a match for these high standards: wheel location comes courtesy of double
wishbones and hub carriers made of lightweight forged aluminium. The
'Gullwing' comes with 3-stage ESP® as standard, providing the driver with access
to the three "ESP ON", "ESP SPORT" and "ESP OFF" modes at the push of a
button.
Ceramic composite brakes, innovative flow-forming wheels.The AMG high-performance composite brakes all-round ensure extremely short
stopping distances even under enormous loads. The newly developed, optional
ceramic composite brakes with larger brake discs guarantee even better brake
performance and lower unsprung masses. The ceramic brake discs will perform
reliably at even higher operating temperatures thanks to their greater hardness,
all combined with an impressive weight reduction of around 40 percent. Lightweight
design was also a key consideration with the wheels: weight-optimised
AMG light-alloy wheels – 9.5 x 19 inch (front) and 11.0 x 20 inch (rear) – based on
the innovative flow-forming principle reduce the unsprung masses while increasing
driving dynamics and suspension comfort. 265/35 R 19 (front) and
295/30 R 20 (rear) tyres developed exclusively for AMG ensure optimum grip.
The design and development phase for the super sports car got underway in the
last quarter of 2006. The intensive vehicle testing programme will be complete by
the end of 2009. Meanwhile, the reinterpretation of the legendary 'Gullwing' is
scheduled to be launched in spring 2010.
Engine and drive trainExclusive high-performance eight-cylinder front-mid engine with dual-clutch
transmission in transaxle configurationEight cylinders and 6.3 litres of displacement with a front-mid engine
configuration, high-revving concept, dry sump lubrication and poweroptimised
intake and exhaust system: AMG has developed an impressive
powerplant for the new 'Gullwing', which transports the super sports car
into the top end of the output range. With peak output of 420 kW/571 hp,
the AMG 6.3-litre V8 engine sets new standards, becoming the world's most
powerful standard-fit eight-cylinder naturally-aspirated engine. Thanks to
the targeted use of fuel-efficiency measures, fuel consumption of around
13 litres Super Plus per 100 kilometres (NEDC combined, provisional figure)
has been achieved. Power transfer in the SLS AMG is handled by a new AMG
dual-clutch transmission with seven gears, which is mounted at the rear in
transaxle configuration and rigidly connected to the engine via a torque
tube.
420 kW/571 hp peak output at 6800 rpm and 650 Nm torque at 4750 rpm – the
new high-performance eight-cylinder engine in the Mercedes-Benz SLS AMG
impressively demonstrates the potential of the AMG 6.3-litre V8 engine unveiled
in 2005 with the designation M156. Based on the M156, which develops
386 kW/525 hp and 630 Nm in the SL 63 AMG for instance, the new M159
eight-cylinder naturally-aspirated engine has been radically improved.
The principal changes relate to the intake and exhaust system, oil supply and
crank mechanism. Over 120 parts and components have been redesigned – all
based on the valuable insights gleaned from over 40 years of motor racing.
In design terms, the M159 – like its stablemate the M156 – is a completely
autonomous development. The combination of high-revving concept and large
displacement combines the best of both worlds: exhilarating high-revving
flexibility accompanied by high pulling power at low engine speeds. The new AMG
V8 for the 'Gullwing' delivers 545 Nm to the crankshaft as low down as 2500 rpm,
while the maximum 650 Nm is on tap at 4750 rpm – more than any
other naturally-aspirated engine in this output and displacement class. This
means the eight-cylinder engine promises dynamic acceleration, instantaneous
pickup and sheer driving pleasure at the highest level, just as it does everyday
relaxed motoring.
Key data at a glance:Cylinder arrangement V8
Cylinder angle 90°
Valves per cylinder 4
Displacement 6208 cc
Bore x stroke 102.2 x 94.6 mm
Distance between cylinders 109 mm
Compression ratio 11.3 : 1
Rated output 420 kW/571 hp at 6800 rpm
Output per litre 67.6 kW/92.0 hp
Max. torque 650 Nm at 4750 rpm
Torque per litre 104.7 Nm
Maximum engine speed 7200 rpm
Mean pressure 13.16 bar
Weight (dry) 206 kg
Power-to-weight ratio 0.36 kg/hp
Optimised cylinder charging thanks to redesigned intake airflowOptimised cylinder charging represents a key element in the increased output
and torque. The recalculated, improved aerodynamic design of the intake airflow
reduces pressure losses, while the all-new valve train improves the gas dynamics.
The fully reworked magnesium intake manifold comes with perfectly matched
variable resonance tube lengths. Eight velocity stacks, each 290 millimetres long
and 51.5 millimetres in diameter, route the fresh air to the combustion chambers.
Two electronically operated throttle flaps – each measuring 74 millimetres in
diameter –, which are adjustable within fractions of a second, sit behind the new
air filters with a volume just under 9500 cubic centimetres: they can be opened
to their maximum in just 150 milliseconds. The result is exhilarating
responsiveness. Two hot-film air mass sensors located behind the air filters
provide the engine electronics with the necessary information about the
temperature and density of the intake air.
Another special feature of the V8 engine is the sophisticated valve train, which is
also derived from the powerful AMG racing engines. The 32 valves in the cylinder
heads are operated by bucket tappets. Their space-saving design permits a stiff
valve train and therefore high engine speeds with large valve opening crosssections,
which, in turn, boosts output and torque. The large intake valves have a
diameter of 40 millimetres, while their opposite numbers on the exhaust side
measure 34 millimetres. Unlike the racing engine, a maintenance-free valve train
with hydraulic valve clearance is fitted.
Four continuously variable overhead camshaftsAll four overhead camshafts are continuously variable over a range of 42 degrees.
Both the intake and exhaust camshafts are adjusted as a function of engine load
and engine speed, ensuring extremely high output and torque values and smooth
idling, and especially low exhaust emissions. Depending on the engine speed, the
valve overlap can be varied to ensure an optimal supply of fuel/air mixture to the
combustion chambers and efficient venting of the exhaust gases. This variable
camshaft adjustment is controlled electrohydraulically and monitored by the
engine management system.
New exhaust system with two headersThe exhaust system has also been redesigned to optimise output: headers with
precisely tailored tube lengths – likewise adopted from the world of motor
racing – deliver a substantial increase in output and torque thanks to improved gas
cycles. The large tube cross-sections in the newly developed, twin-pipe exhaust
system effectively reduce the exhaust gas backpressure. Two relatively small
centre silencers on the underbody and a large, transverse-mounted rear silencer
help ensure optimum weight distribution.
Two backpressure-optimised bulkhead ceramic catalytic converters mounted
directly on the header and two metal catalytic converters on the underbody
ensure effective emission control and compliance with all current emission
standards such as EU 5, LEV 2 and ULEV. The new AMG engine also comfortably
meets the specific requirements of the U.S. market as well as On-Board Diagnosis
II and oxygen sensor diagnosis.
Dry sump lubrication lowers the vehicle's centre of gravityThe engine position was a critical factor in the technical design of the SLS AMG.
According to the specifications, the engine had to be as low and as far back as
possible to keep the vehicle's centre of gravity low and ensure balanced weight
distribution between the front and rear axle. The solution of fitting the eightcylinder
front-mid engine behind the front axle and combining it with a
transaxle, results in a front/rear weight ratio of 48 to 52 percent.
The much lower position of the V8 engine results from the switch to the dry sump
lubrication system, which does away with the otherwise necessary oil pan. The
dry sump lubrication for the M159 comprises a suction pump, a pressure pump
and an external 5-litre oil reservoir fitted in front of the engine. 13.5 litres of
engine oil circulate throughout the entire system. The oil suction pump draws the
oil directly from the crank chambers and the cylinder heads and pumps it to the
external oil reservoir at a maximum rate of 700 litres per minute. The churning
losses normally associated with immersing the crankshaft in the oil sump in the
oil pan can be prevented by efficiently drawing off the engine oil, thus further
improving the effectiveness of what is nonetheless a very efficient engine.
The hydraulic oil pump, designed as a pendulum-slide vane pump, transports the
oil from the external oil reservoir back into the engine, thus ensuring reliable
engine lubrication even with the kind of high lateral acceleration commonly
experienced on a private racing circuit. The demand-driven hydraulic oil pump
takes its cue from the engine revs as well as temperature and load maps stored in
the control unit. All of which lessens power loss within the engine, resulting in a
substantial reduction in fuel consumption. The front wheel arches house two large
radiators with a blower fan integrated on one side to effectively cool the engine
oil.
Outstanding strength and optimum lightweight design also with the engineAnother innovation comes in the guise of the eight forged pistons that are
0.5 kilograms lighter than the cast pistons on the M156 entry-level engine.
Pressure-controlled oil spray nozzles in the crankcase ensure optimal cooling of
the highly stressed piston crowns. Another targeted weight reduction measure
dispenses with steel liners to house the crankshaft main bearings. The crankcase on
the M159 is made entirely of aluminium, weighing around 4 kilograms less than its
counterpart on the M156. Aluminium bolts are also extensively used on the
M159 to further reduce weight. Compared with steel bolts, this saves around
0.6 kilograms. The AMG 6.3-litre V8 engine weighs 206 kg (dry); this results
in a first-class power-to-weight ratio of 0.36 kg/hp.
In typical motor racing fashion, the crankcase uses a rigid bedplate design on the
closed-deck principle. The engine block and cylinder heads are cast from
aluminium-silicon alloys (AlSi7 and AlSi17), which represent the state of the art
in terms of weight, thermal and mechanical resistance and long-term strength.
The engine specialists at Mercedes-AMG use a particularly advanced process for
the eight cylinder walls on the M159 – as was also the case with the M156 – to
produce a tribologically optimal surface, namely a coating applied by twin wire
arc spraying (TWAS). The advantages of this TWAS technology patented by AMG
are extremely low friction and wear, accompanied by outstanding long-term
durability. A considerably harder surface is achieved compared to conventionally
coated cylinder walls. In fact, the cylinder walls of the AMG V8 engine are twice
as hard as conventional cast iron liners – a quantum leap for engine specialists.
Other high-tech components and systems adopted from the M156 include:
the finely balanced crankshaft made out of forged steel;
the water cooling system for the cylinder head using the highly thermal
efficient cross-flow principle familiar from racing engines;
variable coolant control for optimum efficiency;
the computer-controlled fuel supply with fuel pump integrated in the tank.
Powerful cooling module with weight-optimised designWater cooling comes courtesy of a large cooling module mounted behind the
radiator grille. The cooling module also includes the air conditioning condenser
and the power-steering oil cooler. This innovation is particularly beneficial since it
reduces weight by around 4 kilograms compared with previous components –
while also increasing performance. A large suction-type fan placed directly behind
the cooler expels the hot air as required.
Powerful control unit also provides generator managementThe Bosch ME 9.7 AMG engine management system also provides generator
management – another system that helps reduce fuel consumption. Sensors
monitor the charge status of the vehicle battery and reduce the generator output
as soon as the battery is sufficiently charged. To recharge the battery, the system
specifically utilises the engine's overrun phases. The braking energy is converted
into electric energy by means of recuperation.
Through the specific combination of fuel-efficiency measures, NEDC combined
fuel consumption of around 13 litres Super Plus per 100 kilometres is achieved
(provisional figure) – a first-class figure. Ultimately, the new SLS AMG is among
the most powerful super sports car in its segment.
Engine production at the Affalterbach locationThe new V8 powerpack for the 'Gullwing' is produced at the ultra-modern AMG
engine workshops, according to the "one man, one engine" philosophy. That
means the each complete engine is assembled by hand from start to finish by a
single engineer. Every day the AMG engine manufacturing facility with its three
floors covering 9950 square metres produces around 100 high-performance
engines for a range of vehicle models.
AMG seven-speed dual-clutch transmission with RACE STARTThe new AMG dual-clutch transmission with seven gears, four driving modes and
RACE START function is the ideal partner for the powerful eight-cylinder naturally
aspirated
engine. The strengths of this technology, which originated from the world
of motor racing, include spontaneous gearshifts with no loss of tractive force, the
tailored-made control strategy and the supreme ease of shifting. Specially designed
for the high-revving characteristics of the AMG 6.3-litre V8 engine, the dual-clutch
transmission delivers optimum gear ratio adjustment with a close-ratio
configuration. This means that the new transmission provides the 'Gullwing' driver
with even more dynamic acceleration for maximum driving pleasure.
AMG DRIVE UNIT with fully automatic RACE START functionThe AMG DRIVE UNIT is the central control unit for the dual-clutch transmission
and all dynamic handling control functions. On the left next to the selector lever is
the electronic rotary switch for selecting the four driving modes, including
activating the RACE START function. This function allows the driver to call on
maximum acceleration potential and ensures optimum traction to the drive
wheels. The optimum start-off engine speed is set fully automatically and the
'Gullwing' accelerates instantly with its electronically controlled wheelspin – as
an option also up to the top speed. The driver does not need to perform manual
gearshifts; the transmission changes the gears with incredibly short shift times.
Four driving modes for maximum driving pleasure and ride comfortThe dual-clutch transmission supports upshifts under full load both in automatic
mode, and manual mode where the gears can be shifted using the AMG shift
paddles on the steering wheel. Four driving modes for maximum driving pleasure
and ride comfort are available: "C" (Controlled Efficiency), "S" (Sport), "S+" (Sport
plus) and "M" (Manual). In "C" mode, the car always moves off in second gear,
while delivering highly efficient gearshifts. In "S" mode, the engine speed is
allowed to reach a higher level in each gear; the downshifts also feel more
spontaneous. The gearshifts are around 20 percent faster than in “C” mode.
Switching to “S+” mode cuts another 20 percent off shift times, while “M” is the
sportiest mode: here the AMG 6.3-litre V8 engine has even more bite, added to
which the AMG dual-clutch transmission shifts gear another 10 percent faster – a
reduction of 50 percent compared with “C” mode. In “M” mode, the transmission
shifts gear in under 100 milliseconds.
Torque tube with carbon-fibre driveshaft between the engine and
transmissionThe dual-clutch transmission forms a fixed unit with the V8 engine via the torque
tube. Engine and the transmission mounted at the rear axle – known as a
transaxle – are connected to each other to ensure flexural and torque rigidity and
to support each other. All of which translates into decisive advantages in terms of
driving dynamics and ride comfort since this sophisticated solution provides a
backlash-free drive train. The 1.64-metre-long torque tube comprises a one-piece
aluminium sand-cast casing and weighs less than 25 kilograms. A driveshaft
rotates inside the tube at the engine speed. As with the Mercedes-Benz C-Class
DTM racing touring car, the shaft is made out of carbon fibre. A key advantage of
this high-tech material: despite its high strength, the carbon-fibre shaft tips the
scales at just 4 kilograms. Consequently, the 1.71-metre-long driveshaft, which
has to transmit 650 Nm torque from the engine to the dual-clutch transmission, is
around 50 percent lighter than a steel equivalent.
Suspension and braking systemUncompromising high-tech from motor racing for consummate racetrack performance
Technology from motor racing – whatever applies to the complete drive train
on the new Mercedes-Benz SLS AMG, holds equally true for the suspension
and braking system. The aluminum double-wishbone suspension is tailored
to consistent lightweight design and superb driving dynamics. The AMG
high-performance braking system is also available as an option in an all-new,
high-performance ceramic version.
The commitment of Mercedes-Benz and AMG to building an alluring super sports
car that combines consummate racetrack performance with hallmark Mercedes
long-distance comfort has given rise to an ingenious suspension layout. All four
wheels are located on double wishbones with a track rod, a technology that has
proven itself in motor racing, right through to Formula 1. With a double-wishbone
axle, the wheel location and suspension function remain separate; the
spring/damper struts are supported on the lower wishbone. The double-wishbone
concept with its high camber and track rigidity positively locates the wheel with
minimal elastic movements, providing the driver with an optimum sense of road
contact when driving at the limits.
Source: AMG Private Lounge
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