Mercedes-Benz M278 engine

Mercedes-Benz M278
Overview
Manufacturer	Daimler AG
Production	2010–
Chronology
Predecessor	Mercedes-Benz M273, Mercedes-Benz M156

The Mercedes-Benz M278 is a family of direct injected, Twin-Turbocharged, V8 gasoline automotive piston engines.

The M278 is derived from the company's previous M273 V8 engine, sharing its bore pitch, aluminium engine block, and Silitec aluminium/silicon low-friction cylinder liners. In contrast to the port-injected M273, the M278 features gasoline direct injection, with piezo-electrically actuated fuel injectors for more precise fuel delivery, and multi-spark ignition, which enables the spark plugs to be fired multiple times over the combustion sequence for more efficient combustion. Other changes relative to the M273 include an increased adjustment range for the variable valve timing system, a new timing chain arrangement, and new engine accessories (such as the oil pump, water pump, fuel pump, and alternator) which reduce parasitic loads. Many of these new features are shared with the M276 V6 engine family, which was announced at the same time.

While the M273 was naturally aspirated, the M278 features twin turbochargers, one per cylinder bank, producing 0.9 bar boost pressure in most configurations.

Mercedes-Benz estimate that these changes, in conjunction with vehicle modifications such as a stop-start system, allow the 4.6 liter M278 to have 22% lower fuel consumption and CO2 emissions than the 5.5 liter M273 while producing more power (429 hp versus 382 hp) and torque (516 ft·lbf versus 391 ft·lbf). The M278 is also more refined than its predecessor.

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