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 aluminium

The 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 hp

The 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 strength

The 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 tube

The 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 train

Exclusive high-performance eight-cylinder front-mid engine with dual-clutch

transmission in transaxle configuration

Eight 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 airflow

Optimised 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 camshafts

All 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 headers

The 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 gravity

The 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 engine

Another 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 design

Water 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 management

The 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 location

The 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 START

The 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 function

The 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 comfort

The 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

transmission

The 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 system

Uncompromising 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