New V8, inline sixes for S-Class

Next year’s facelift of Mercedes-Benz’s flagship S-Class limousine will usher in a new range of V8, inline six-cylinder and four-cylinder engines.

The new powertrains won’t stay with the S-Class, though, with the modular range of petrol and diesel engines set to sprinkle throughout the Mercedes-Benz range.

Based around modular 500cc single-cylinder architecture, the all-new engines will all use turbocharging and will range from in-line fours to inline sixes and an AMG-developed 4.0-litre biturbo V8.

The all-new engines will include a 2.0-litre four-cylinder turbodiesel, a 3.0-litre turbo-diesel, a twin-scroll turbo four-cylinder petrol engine and an inline turbocharged petrol-powered six-cylinder engine, along with the M176 V8.

Aimed at improving performance and slashing real-world NOx and CO2 emissions, the new engines will benefit from unprecedented economies of scale for the brand, sharing components and production facilities.

For the first time at Mercedes-Benz, all four new engines have been designed from scratch to work with hybrid electric power as Benz battles to keep its internal-combustion knowledge relevant under tougher emissions laws in a looming electrified future.

“The optimisation of advanced high-tech engines plays a key role in our road map towards sustainable mobility,” Daimler R&D boss Dr Thomas Weber insisted.

“For the mobility of the future, we are deliberately not committing ourselves to one solitary form of drive system, but to a coexistence of efficient and clean petrol engines, diesels, plug-in hybrids, battery and hydrogen drive systems.

“High-tech engines and electrification are not in competition with each other. On the contrary: they complement each other perfectly in many applications.”

The range will be headed by the 4.0-litre M176 V8, which will power the S 500 and replace its sweet 4.6-litre M278 powerplant by delivering more power, more torque and lower emission levels and reduced fuel consumption.

The new engine is derived from the M177 and M178 V8s in the AMG E 63 and the GT coupe and will deliver more than 350kW of power and around 700Nm when it reaches production towards the middle of next year.

With between 100 and 200 bar of fuel pressure and two turbochargers nestled in between the cylinder banks, it will also have the ability to shut down four cylinders, two on each bank, to effectively run as a V4 in light load situations.

It will shut down cylinders two and three on the right bank and five and eight on the left at constant engine loads between 900 and 3250rpm, though can jump back into V8 mode more or less instantly depending on torque or rpm demands.

The Untertürkheim-built V8 will remain as a V8 in Sport mode, though not in its default, comfort or eco modes, when a pin activates a different camshaft.

It will also usher in an era of 48-Volt power for Mercedes-Benz, which will see its Integrated Starter-Alternator (ISG) and electric auxiliary compressor (eZV), which boosts up 70,000rpm in just 300 milliseconds. Together, the two systems act as a hybrid-lite, delivering an extra 10 to 15kW of boosting performance when it’s needed to cover for either turbo lag or spool-up.

Benz isn’t giving away the S500’s performance data yet, but insists its fuel economy will be 10 percent lower than the current car with the new 3982cc V8 in place. Emissions should also improve, with Benz making a cordierite particulate filter standard on its M256, M176 and M264 petrol engines from next year, too.

The S-Class will also receive the inline six-cylinder petrol engine, dubbed M256 internally and boasting more than 300kW of power.

While Benz isn’t making specific performance claims for the car, it admitted it will have more than 500Nm of torque, giving it 20 per cent more power and four per cent more torque than the current V6.

It uses both a single turbocharger and the ISG and eZV with a 15 percent reduction in engine-related CO2 and highlighting the 90mm bore spacings of the new modular engine family.

The first of the new engines out of Benz’s €3 billion powertrain investment program was the OM654 four-cylinder turbo-diesel which debuted in the E 220d in spring this year.

The 1950cc OM654 four-cylinder diesel engine uses a single variable-geometry turbocharger, 2050 bar of fuel pressure and a stepped-crown combustion process to deliver 143kW of power and 400Nm of torque

The extra work on emissions has allowed Benz to bypass its much-criticised thermal switches to cut off the exhaust-gas recirculation system at high or low ambient temperatures and deliver much improved real-world emissions.

A version of the new OM656 in-line six-cylinder turbo-diesel is already on sale, but it’s not as advanced as the unit planned for the S-Class, which will have more than 230kW of power and more than 650Nm of torque.

Those figures alone will make it the most powerful, and strongest diesel engine Mercedes-Benz has ever offered in a passenger car.

A 20 per cent step up in power and a five per cent lift in torque over the OM642 3.0-litre V6 turbo-diesel, it gets most of its gains by nestling the exhaust gas after-treatment systems very close to the exhaust manifold, and it uses 2500 bar of fuel pressure in its direct-injection system.

The alloy-block inline six also uses two turbochargers, with one working below 3000rpm and the other covering higher revs and power demands, while it uses Camtronic variable valve lift for the first time in a Benz diesel.

Its consumption figures are claimed to be down by seven per cent over the outgoing 3.0-litre V6 turbo-diesel.

The investment in the two new engine families included an astonishing new Powertrain Integration Centre in Sindelfingen, Germany, that can house 10 full cars or prototypes, running 24 hours a day with or without drivers.

The cells are all self-fueling and include four exhaust test benches, three application roller test benches, three powertrain test benches and two cold-start chambers.

“It’s the most modern test bench facilities in the automotive industry and it plays an important part in helping us reach our goal of taking more and more testing off the road and onto the test stand,” Daimler’s director of gasoline and hybrid powertrain, Mario Murwald, said.

“In Sindelfingen alone we have invested about €600 million in large-scale test rigs and research and development facilities.

“The highlights include high-precision torque measurement directly at the axles, the climatic altitude chamber that enables us to simulate an altitude of up to 5000 metres, fully automatic operation minus driver, full temperature and humidity adjustment, automatic refueling and 98% of electrical brake energy fed back into the grid.”

The cells can each run between -30 and +42 degrees and can manage diesel, gasoline, fuel cell or BEV and CNG, though only the petrol and diesel models can be refueled automatically.

“All the manoeuvres can be done on the road but the test bench gives us several advantages,” explained Verena Ricke of Daimler’s Powertrain Testing department.

“We can change driving modes; decelerating, braking, changing gear, 24 hours a day.

“We can simulate different responses of the accelerator pedal for example, without taking the car off the road.

“One of the great advantages is the reproducibility because there is no rain or heat changes and we can keep all the conditions stable.”

The rolling test benches can cope with 500kW of power (330kW for the rear roller) and are flexible enough take any wheelbase or track width in the current or future Mercedes-Benz armoury.

It can simulate up to 250km/h and cools not just the car, but the tyres and the rear differential, too.

Its engine test benches are unique in the industry, bolting directly to wheel extending bolts to give it unprecedented accuracy, with electric power capable of soaking up 270kW of power and 4000Nm of torque per wheel, so that’s likely to be enough for a while.

“We have highly precise torque measurements and fine control of the machine, so we can test any longitudinal test you can dream up with this,” Marcus Sonntag, Daimler’s head of Valuation and Measurements, Validation, said.
“Compared to testing on the road the test bench allows us to have an early evaluation at the highest level of precision.

“Of course you have to say that we can never replace road testing completely because a car always has to function on the road but there are detailed tasks that we can shift to the test bench.”