Mercedes brings the good, old six-cylinder series back to the luxury class . The E- and S-Class in particular benefit from the new engine generation – but there are also new four-cylinder units derived from it.
The long-standing design is appreciated by many customers, especially for their smoothness. But that alone did not make the Stuttgarters rethink.
Mercedes M 256: New straight-six saves fuel
For one, the inline engine is simply cheaper, since only a cylinder head and valve train is needed. On the other hand, the departure from the V- engine is also due to the changed demand. The V6 is a descendant of the big eight-cylinder.
However, it is being asked less and less why a common basis and production with the four-cylinders is more likely in the future. Since they are just in rank and file, the cylinders are arranged one behind the other in the six-pointer.
Electrification of the drive: 48-volt electrical system is coming
That, however, is not the only innovation. Mercedes is also the topic of 48-volt electrical system at the top of the agenda. And that brings the new six-M 256 from mid-2017 in the then newly revised S-Class. But in turn: The gasoline engine , like all units of the new engine family, the uniform cylinder volume of a good half a liter, making in total so three liters of displacement.
What can be generated from this performance, you do not want to reveal in Stuttgart yet. Only so much is revealed: more than 408 hp and more than 500 Newton meters of torque – at the same time decrease compared to the current model in the S 400 consumption and thus the CO2 emissions by 15 percent.
Electric motor replaces the belt drive
Of course, the new, old cylinder arrangement is not responsible for the restrained thirst. Rather, engine-internal optimizations, for example, reduced friction, provide for the under-consumption. And of course the ISG. The “integrated starter generator” sits between the engine and the gearbox and replaces the classic belt drive.
This is where the 48 volt network comes into play, after all, the ISG is basically nothing more than an electric motor. He takes over the starting of the gasoline engine and contributes when accelerating force, which is to provide a sheer “brutal passage”. In addition, it allows a load point shift, that is, the gasoline engine can be operated with lower consumption, since he no longer has to provide the maximum power. Conversely, when braking, the ISG ensures that excess energy is transformed back into electricity, not just heat.
Since the belt drive is completely eliminated. All auxiliary consumers such as water pump or air conditioning compressor are designed electrically; thus they can also be controlled as needed. And another component uses the new 48-volt network: The electric auxiliary compressor, which ensures that the burner already provides plenty of torque before the large exhaust gas turbocharger comes into gear.
Speaking of exhaust gases: Since the in-line engine, although longer, but leaner than a V-engine, almost the entire exhaust aftertreatment could be built directly to the engine ran. Only the particulate filter – yes, which will be available in the future for the petrol engine – is still in the subsoil.
Also a new four-cylinder at the start
The R6 is not the only new engine in the Mercedes stable. Derived from this, there is a new two-liter four-cylinder (M 264). Also with 48 volt support, but a belt-driven starter generator that also provides extra boost and can recuperate energy. Mercedes speaks of about 272 hp power. In the refreshed S-Class, the engine will not be used, its premiere will take place in late 2017, probably in the E-Class.
New diesel generation is already driving
There, in the E 220 d, already operates a four-cylinder diesel of the new generation. The Mercedes will soon also a six-cylinder version aside; as in the gasoline also in series and with three liters of displacement. The OM 656 delivers over 313 hp and pushes more than 650 Newton meters on the crankshaft. Unlike the four-cylinder Mercedes sets here on double charge and an increased injection pressure of 2,500 bar. The 48-volt network or a starter generator are not yet provided for the diesel.
Eight-cylinder with cylinder deactivation
This also applies to the new twin-turbo eight-cylinder M176, which will debut as the six-cylinder diesel also in the S-Class. The V8, which is related to the AMG GT and C 63 engines, is characterized above all by the cylinder deactivation. If not required, the combustion chambers 2, 3, 5 and 8 are shut down by means of sliding cam pieces of the intake and exhaust camshaft.
If the driver gets more power and the engine revs up over 3250 revolutions, or if you switch to Sport mode, the part-time four-cylinder will be back in eighth position within milliseconds. Together with a displacement reduction from 4.6 to 4 liters and further internal engine improvements, consumption is expected to fall by around ten percent. At the same time the performance increases from 455 to over / 476 hp. This sets Mercedes a new benchmark in the S 500.