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The Mercedes-Benz M278〔(Mercedes' New V Engine Family )〕 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, aluminum engine block, and Silitec aluminum/silicon low-friction cylinder liners.〔(Mercedes-Benz New V6 and V8 Engines are More Powerful and More Efficient )〕 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.〔()〕 The entire M278 lineup avoids the United States Gas Guzzler Tax, a first for V8 production engines from Mercedes-Benz.〔()〕 ==M278 (base)== The basic M278 has a displacement of with a bore of 92.9 mm and stroke of 86 mm. Output is 429 hp (320 kW, 435 PS) at 5250 rpm with 516 ft·lbf (700 N·m) of torque at 1800-3500 rpm for S-Class, CL-Class, SL-Class, and GL-Class models.〔 CLS-Class, E-Class, and M-Class models are derated to 402 hp (300 kW) with 443 ft·lbf (600 N·m) of torque at 1600 rpm.〔(2012 Mercedes-Benz CLS550 - First Drive Review - Auto Reviews - Car and Driver )〕 Although it no longer corresponds with the engine displacement, all of the above models are still badged as "550". The GL-Class, besides the GL550 above, also features the GL450 trim that carries a detuned version of the 4.6 L engine making 362 horsepower and 406 pounds-feet of torque 〔()〕 For 2014 S-Class models (chassis code W222), power is increased to 455 hp (335 kW) at 5250 rpm, while torque remains at 516 ft·lbf (700 N·m) between 1800-3500 rpm. .〔(2014 Mercedes S-Class Sets New Standards in Automotive Development )〕 These engines are mated to the 7G-Tronic 7-speed automatic transmission. Applications:〔 * 2011– Mercedes-Benz S-Class (S500 in Europe, S550 in the US) * 2011– Mercedes-Benz CL-Class (CL500 in Europe, CL550 in the US)〔()〕 * 2011– Mercedes-Benz CLS-Class (CLS500 in Europe, CLS550 in the US) * 2012– Mercedes-Benz SL-Class (SL500 in Europe, SL550 in the US) * 2012– Mercedes-Benz E-Class (E500 in Europe, E550 in the US) * 2013– Mercedes-Benz GL-Class (GL500 in Europe, GL550 in the US) 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Mercedes-Benz M278 engine」の詳細全文を読む スポンサード リンク
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