Mercedes-Benz M278 engine

The Mercedes-Benz M278 is a family of direct injected, Bi-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 from Honeywell, one per cylinder bank, producing 0.9 bar (13 psi) boost pressure in most configurations. Mercedes-Benz estimated that these changes, with vehicle modifications such as a stop-start system, give the 4.7–litre M278 22% lower fuel consumption and CO2 emissions than the 5.5–litre M273 while producing more power 320 kW (435 PS; 429 bhp) versus 285 kW (387 PS; 382 bhp) and torque 700 N⋅m (516 lb⋅ft) versus 530 N⋅m (391 lb⋅ft). The entire M278 lineup avoids the United States Gas Guzzler Tax, a first for V8 production engines from Mercedes-Benz.