The fastest Mercedes-Benz-badged car in the world is about to get a whole lot hotter. And more expensive.
With the paint still wet on its SLS GT
, AMG is showing the world the even-faster, even-angrier SLS Black Series.
With more power, less weight, tauter handling and, bizarrely, a lower top speed, AMG claims its fifth Black Series model will bring the handling package of its SLS GT3 race car to the road.
It has eked another 44kW of power from the standard SLS Coupe’s 6.2-litre V8 to peak at 464kW and slashed 70kg from the standards SLS to weigh in at 1550kg. It’s also 29kW upstream of the just-released SLS GT as well.
AMG combines this with an upgraded version of its seven-speed paddle-shift transmission, a coil-over suspension system, carbon-ceramic brakes, sticker tyres and an electronic diff lock to create the most potent rear-wheel drive car it’s ever built. It results in a snarling, snorting monster that blasts to 100km/h in 3.6 seconds and tops out at 315km/h, but AMG insists the SLS Black Series does its best work in corners. It also has a shorter final drive ratio than the standard SLS or the SLS GT (which explains its slightly slower top speed).
The Black Series features wider, more aggressive bodywork, bigger air intakes, darkened headlights, deep front and rear undertrays, a massive air outlet carved into the bonnet and a large rear diffuser. For those who aren’t so concerned with elegance, there’s also the option of a huge, race-bred rear wing.
The already-lean internals of the all-alloy V8 have been overhauled, with a new valve train, fresh camshafts, upgraded camshaft geometry and new bucket tappets taken from racing technology.
The air intake ducting is also freer breathing to help the engine’s maximum speed jump from 7200rpm to a more race-like 8000rpm
, but the Black Series pays a price in torque, which not only falls from the SLS GT’s 650Nm to 635Nm, but arrives 750rpm later in the rev range, too. The Black Series AMG’s crank assembly has also been modified to cope with the higher peak engine pressures. The upgrades include new crankshaft bearings and new bolts for the connecting rods.
Both the entire oil and water pumping systems are upgraded, including a new oil pump and bigger diameters for the crankshaft’s oil bores.
But the most innovative change to the engine is actually outside the block, with AMG adding a gas strut brace between the engine and the body to stop it moving under load changes. On a racetrack, this system is supposed to stiffen or slacken to compensate for “undesired load change reactions in highly dynamic driving on the racetrack,” according to AMG development boss, Tobias Moers.
Oddly, though, while the repowered SLS Black Series is the most powerful conventional car AMG has ever built, it’s not the most powerful car on AMG’s books. Its 464kW of power looks astonishing until you consider that the electric version of the SLS
cranks out 552kW of power and, with 1000Nm, has 365Nm more torque, too.
The search for performance doesn’t end at the Black Series’ exhaust manifold, either. AMG has developed its own fully titanium exhaust set up for the Black Series that not only cuts 13kg from the old steel system, but weighs just 17kg overall. It has mufflers in the centre and at the rear of the car and uses fan-type exhaust pipes to free up the gas flows as well to improve responsiveness.
AMG has also taken extraordinary steps to help the handling, including dropping its seven-speed DCT transmission 10mm lower into the chassis and then using smaller versions of the engine’s gas strut to keep it locked in place regardless of the torque load on it. Oddly, though, the Black Series transmission spreads its expertise across Comfort, Sport, Sport+ and Manual modes, even though the just-launched (and supposedly softer) SLS GT has dumped the Comfort setting altogether.
Nevertheless, the Black Series adopts the software developed for the SLS GT to cut its shift times to 60 milliseconds and introduces a double-declutching function for more aggressive downshifts. Not that the SLS has ever suffered from subtlety, but there’s now an enormous blip on the throttle when changing down in Sport or Manual modes. It also has a new (and somewhat belated) “temporary manual” mode, so the driver can just pluck a shift paddle to change gear, even if the car is in one of its automatic modes.
One key to the improved performance is the shorter final-drive ratio already mentioned, though some might find it odd that AMG has replaced the SLS’s standard mechanical limited-slip diff with an electronic diff lock. Integrated into the transaxle unit, the newly developed diff lock comes with variability in locking on both acceleration and deceleration and has more sensitive electronics than any system of its type. It means AMG has also tuned the ESP settings to the diff lock, including different levels of aggression for ESP, ESP Sport handling mode and ESP Off. It also hooks in to the Race Start launch-control function.
While the Black Series still rides on aluminium double wishbones all around, that’s about where its similarities to the standard car end. The hunt for better track performance called for a complete overhaul of the SLS’s handling package and the adaptive suspension of the AMG Ride Control is now tauter, with just Sport and Sport+ options for its drivers, plus individual settings.
Spring retainers for the coil-over springs provide drivers the facility to tweak individual wheel loads for individual circuits or conditions, and AMG has stretched the track widths of the SLS by 20mm at the front and 24mm at the rear to add grip in fast corners. Elastokinematics are stiffer by 50 percent on the front axle and 42 percent on the rear for the same reason.
Upgraded 10-spoke alloys, measuring 10x19 at the front and 12x20 at the rear, save the SLS Black Series four kilograms, while it also scores a new front stabilizer bar and new front wheel carriers. The steering has also been tweaked, but the real grip will be unlocked via its custom-made Michelin Pilot Sport Cup 2 rubber, with 275/35 R19s at the front and 325/30 R20s lurking at the back.
Inside the lighter wheels sits a monster set of carbon-ceramic rotors, stretching out to 402mm at the front and 360mm at the back. The ventilated rotors are harder than the optional carbon-ceramic brakes on the standard SLS and, at 16kg lighter than the conventional brakes, save around 40 percent in weight. That’s no accident, because one of the keys to the car’s improved performance in the mid-range is its 70kg weight reduction, which helps it to a 2.45kg/hp power-to-weight figure.
The weight cull has affected everything from the bonnet to the small panel behind the seats and the diagonal underbody braces. Even the torque tube, which delivers the engine’s torque to the rear-mounted gearbox, is carbon-fibre and cuts the 26.6kg cast-aluminium standard part down to 13.3kg. The carbon-fibre-reinforced plastic drive shaft inside the torque tube is only 4.7kg.
Even the conventional battery has been thrown out and replaced by a lightweight (8kg lighter) Lithium-Ion unit, normally found in electric cars or hybrids.
The cabin has also contributed to the lower weight, with AMG Sports seats cutting 15kg from the standard electric units. Ditching the Comand unit, with its satnav and entertainment system operations, has saved another 6kg.
A BLACK HISTORY
This all began in with one of the most unlikely machines in the Mercedes-Benz range – the SLK. Widely panned as a soft sports car, AMG made sure it wasn’t disrespected any longer by creating the SLK55 AMG Black series in 2006.
It followed that up with the SLK63 AMG Black Series in 2007, then the V12-powered SL65 AMG Black Series in 2008 before taking three years off.
It came back with a bang with 2011’s C63 AMG Coupe Black Series, and now the SLS makes five.
The key data at a glance:
||SLS AMG Coupé Black Series
|Bore x stroke
||102.2 x 94.6 mm
||11.3 : 1
||464 kW (631 hp)
||at 7400 rpm
||at 5500 rpm
|Maximum engine speed
|Engine weight (dry)
|Fuel consumption, NEDC combined
||13.7 l/100 km
|Acceleration 0-100 km/h
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