Mercedes rolls out new generation V8, inline 4 and 6 cylinder engines
Mercedesblog
Cristi Stefan
October 29, 2016
Mercedesblog
Cristi Stefan
October 29, 2016
M176 AMG developed new V8 for the S-Class
The new V8, codenamed M176, will be built in Untertürkheim and is dedicated to the Mercedes flagship model, the S-Class. It will be offered from mid-2017, replacing the current M278 V8 with 455 hp in the S 500. Official power output has not been announced, but Mercedes promises more than 476 hp and 700 Nm at 2.000 rpm.
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The V8 will get advanced tech solutions such as the turbochargers mounted in between the cylinder banks (‘hot inner V’), a formation first seen on the Mercedes-AMG GT V8 (M178). This particular arrangement generates a 5% power gain compared to the old M278 V8. The engine is of closed-deck construction, which means that the engine block cover plate is extensively closed in the area around the cylinders. The engine block is of an aluminium alloy and produced by permanent mould casting. The cylinder head uses an aluminium-zirconium alloy, which is a better conductor of heat than the standard aluminium alloy.
The new V8 biturbo employs a centrifugal pendulum to reduce both the fourth-order vibrations in eight-cylinder mode as well as the second-order vibrations in four-cylinder mode. A combination of biturbocharging and direct petrol injection with spray-guided combustion increases the thermodynamic efficiency, thereby reducing the fuel consumption and exhaust emissions. Particularly fast and precise piezo injectors spray the fuel at high pressure into the eight combustion chambers. Multiple injection occurs on-demand, ensuring a homogeneous fuel/air mixture. The delivery of fuel is electronically controlled and fully variable for a fuel pressure between 100 and 200 bar.
Fuel economy is also paragon for the new engine. According to Mercedes, the new V8 consumes 10% less fuel thanks to its smaller displacement (3.982cc versus 4663cc) and clever cylinder deactivation system. Between 900-3250rpm (in Comfort or Economy driving modes only) cylinders 2, 3, 5 and 8 are shut off. The cylinders can be reactivated in milliseconds as soon as the acceleration is pressed on or as soon as the engine speed goes above 3250 rpm. CAMTRONIC valve timing reduces the pumping losses while improving the overall efficiency of the remaining four cylinders by shifting the operating point towards higher loads.
The cylinders are turned on and off by the interplay between engine control and actuators on the cylinder head. The switchover to four-cylinder operation is accomplished by eight actuators that act on the axially movable cam parts of the intake and exhaust camshafts via a selector. These cam parts are held on the carrier shaft by gears and are locked in the respective end positions by means of a locking mechanism. The intake and exhaust valves of cylinders 2, 3, 5 and 8 do not open due to the zero-lift cams of the cam parts. At the same time, the fuel supply and ignition are deactivated, so that no unburned mixture is left in the deactivated combustion chamber.
The M 176 has exhaust aftertreatment with two catalysts directly mounted on the engine and on the underfloor. The as-standard particulate filter is part of the exhaust system under the floor.
More at linkMercedes-Benz six-cylinder engine M256.
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M256 six-cylinder inline gasoline with mild-hybrid tech
Another significant premiere is the new six-cylinder inline gasoline engine (codenamed M256), the first-ever Mercedes engine designed to support mild hybrid and electrification applications right from the outset. It will debut in 2017, again on the flagship S-Class, at first, but it will eventually filter down to the smaller E-Class.
The main innovation is the 48V electrical system. The Integrated Starter-Alternator (ISG) and electric auxiliary compressor (eZV) combine to produce a power boost that negates turbo lag, while the system also serves the classic roles of powering the water pump and air-conditioning compressor. The 48V ISG is also responsible for hybrid functions such as boost (up to 15 kW), energy recovery, coasting and shifting of the load point – the engine can be operated in a more favourable area of the engine map; load increase/reduction depending on the state of charge of the battery.
Packaging has a lot gain from the new inline configuration. The engine is shorter due to the absence of a belt drive so Mercedes freed more space for ancillary components on either side of the new inline six cylinder unit. Its performance is also as dynamic as that of a V8, as the new six-cylinder in-line engine comes with an especially intelligent form of turbocharging: assisted by the ISG at start-off, the electric auxiliary compressor (eZV) guarantees immediate high torque when driving off and accelerating, bridging the time before the large exhaust turbocharger cuts in. The electric turbocharger accelerates to 70,000 rpm within 300 milliseconds, ensuring an extremely spontaneous reaction from the engine.
The new engine has 2,999 cc and develops more than 408 hp and 500 Nm (versus 2,996 cc and 333 hp for the old M276 V6) while CO2 emissions have gone down by 15%. Another trick used by Mercedes is the first-ever particulate filter to be mounted on a series gasoline engine. It traps soot particles and it will be gradually appear on all future engines, beyond the all-new M256 inline-six cylinder.
