At market launch, the new roadster starts with two output levels of the AMG 4.0-litre V8 biturbo engine. And for the first time in its history, the SL also transfers the power to the road with all-wheel drive.
In the top model SL 63 4MATIC+ (combined fuel consumption 12.7-11.8 l/100 km, combined CO2 emissions 288-268 g/km) the engine develops 430 kW (585 hp) and provides a maximum torque of 800 Nm over a wide rev range from 2500 to 4500 rpm. The roadster’s top engine thus conveys effortless superiority in every rev range. The acceleration from 0 to 100 km/h in 3.6 seconds illustrates this, as does the top speed of 315 km/h. In the Mercedes-AMG SL 55 4MATIC+ (combined fuel consumption 12.7-11.8 l/100 km, combined CO2 emissions 288-268 g/km), the V8 engine delivers 350 kW (476 hp) and a peak torque of 700 Nm. The sprint from standstill to 100 km/h takes 3.9 seconds, the top speed is 295 km/h.
The further developed AMG 4.0-litre V8 engine still operates with biturbo charging, in which the two turbochargers are not located on the outside of the cylinder banks, but in between them in the cylinder-V. The advantages of the “hot inside V”: a compact engine design, spontaneous response of the turbochargers and low exhaust emissions thanks to optimal airflow to the close-coupled catalysts.
To further improve response, turbochargers with twin-scroll technology are used. Here, the housing of the turbocharger is divided into two parallel flow channels. Combined with two separate exhaust ducts in the exhaust manifold, this makes it possible to control the exhaust gases on the turbine wheel separately. One duct is fed by the exhaust gases of the first and second cylinders of a cylinder bank, the other by the exhaust gases of the third and fourth cylinders. The aim is to prevent the individual cylinders from having mutually adverse effects on the gas cycle. This reduces the exhaust gas back-pressure and improves the gas exchange. The results are increased output owing to improved cylinder charging with fresh mixture, more torque at low revs and immediate response times.
Engine features also include weight-optimised pistons, an adapted air intake and intercooling system, as well as extensive software developments. The jet-guided direct petrol injection with piezo injectors, the all-aluminium crankcase, the 4-valve technology with camshaft adjustment, the air-to-water intercoolers, the alternator management, the ECO start/stop function and the gliding mode have been retained.
Special modifications for use in the SL
For use in the SL, the internally named M 177 engine received a new oil pan, repositioned intercoolers and active crankcase ventilation. The intake and exhaust ducts have been optimised for even more effective gas exchange and the exhaust gas routing for the catalytic converter box and petrol particulate filter has been enlarged. The developers achieved the increased output of the SL 63 4MATIC+ primarily through higher boost pressure and greater air flow, as well as modified engine software. To sum up, the eight-cylinder engine thrills with its exceptional power delivery and powerful acceleration in all engine speed ranges combined with maximum efficiency for low consumption and emission values.
In the SL 63 4MATIC+, the eight-cylinder engine features active engine mounts. The SL 55 4MATIC+ can be optionally equipped with this as part of the AMG DYNAMIC PLUS Package. The mounts solve the conflicting goals of achieving as soft a connection as possible to the powertrain for high comfort and as rigid a connection as possible for optimum driving dynamics, by steplessly and quickly adapting their rigidity to the respective driving conditions. These are liquid-filled rubber mounts. The vehicle sensors detect the respective driving situation as well as the resulting vibration behaviour of the engine and pass this information on to a control unit. It regulates the force with which the engine is coupled to the body and thus optimises the handling. For this purpose, a magnetic damper fluid is pressed through an annular gap of a coil in the mount. Differently high currents generate a magnetic force that regulates the flow and thus the engine mounts according to the information from the control unit.
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