Smarter new engine family to underpin Mercedes of the future
In the push for more efficient engines, the world is moving to downsize and turbocharge everything at the moment - even the Ford Mustang is available with an EcoBoost motor. In spite of the downsizing push, Mercedes hasn't given up on the classic inline six and V8 yet. The German giant has unveiled details about its new family of engines, complete with support for electric turbocharging.
Although there were five engines announced, the most exciting in the range is undoubtedly the new inline-six code named M256. Inline-six engines have long been hailed as the smoothest engine configuration out there, and are still favored by the development team at BMW, but it's been eighteen years since Mercedes offered a car with one under the hood.
The new 3.0-liter M256 motor is expected to produce upwards of 300 kW (408 hp) and 500 Nm (369 lb ft) of torque, compared to the 245 kW (333 hp) and 480 Nm (354 lb ft) on offer in the current M276 — which is a V6 that's been in service since 2010. In spite of the extra power, the new engine should also be around 15 percent more efficient than the current offering, and an integrated particulate filter makes it much cleaner as well.
Interestingly, M256 is one of the first engines to make use of an electric turbo. Unlike a regular turbocharger, which is reliant on exhaust gas to spin up and provide a power boost, the Mercedes electric turbo can spin up to 70,000 rpm in just 300 milliseconds, offering a big shove in the back with almost no perceptible lag. It's driven by a new 48V electrical architecture, which also serves as an alternator and feeds high-draw elements like air conditioning and the starter motor.
Further up the engine lineup, Mercedes has also committed to the V8 engine with the twin-turbo M178 engine. The new 4.0-liter motor has been developed by AMG for use in regular Mercedes, and develops more than 350 kW (476 hp) of power - 15 kW (20 hp) more than the current M278 V8 can manage. Despite the extra grunt, the new engine is around 10 percent more efficient than the one it replaces.
These improvements come courtesy of extensive work cutting down on friction within the engine, along with a clever cylinder deactivation system allowing the motor to run on four cylinders under light loads. As soon as the revs drift north of 3250 rpm, or if the driver really puts his foot down, the deactivated cylinders spring back into action.
It's not all high-end AMG six and eight-cylinders in the refreshed engine lineup, though. The new M264 turbocharged inline-four with a specific output of 100 hp (75 kW) per liter will make its debut next year. It makes use of a twin-scroll turbocharger to offer up better low-down response without sacrificing top-end power. Although it also makes use of a 48V electrical system, there's no electric turbocharging for the smallest new motor.
Alongside the range of updated petrol engines will sit a diesel inline-six and inline-four engine, however neither has been treated to quite the same degree of innovation as the petrol engines. The four-cylinder made its debut in the E220D earlier this year, while the inline-six uses improved thermal management to minimize efficiency losses on cold starts.
The new engines will make their debut in the 2017 Mercedes S-Class.