The second variant, designated M157,[9] is tuned by Mercedes-AMG for use in higher-performance models. This version has a displacement of 5.5 liters (5461 cc) with a bore of 98.0 mm and stroke of 90.5 mm.[10] Increased power and torque comes from the increased displacement as well as higher boost pressure of 1.0 bar.
There are six states of output with the M157. For the S-Class and CL-Class, power is 536 hp (400 kW, 544 PS) at 5500 rpm with 590 ft·lbf (800 N·m) of torque at 2000-4500 rpm, or 563 hp (420 kW, 571 PS) at 5500 rpm with 664 ft·lbf (900 N·m) of torque at 2500-3750 rpm with the optional AMG Performance Package.[10] For the 2012-2013 E-Class and CLS-Class, power is 525 hp (386 kW) with 516 ft·lbf (700 N·m) of torque in standard tune, or 557 hp (410 kW) with 590 ft·lbf (800 N·m) of torque with the AMG Performance Package.[11] Beginning with the 2014 E-Class and CLS-Class, power increases to 557 hp (410 kW) with 531 ft·lbf (720 N·m) of torque for standard tune, or 585 hp (430 kW) with 590 ft·lbf (800 N·m) of torque for "S-Model" variants.[12][13]
These engines are mated to the AMG Speedshift MCT 7-speed semi-automatic transmission, which replaces the 7G-Tronic's torque converter with a wet clutch pack.[14] Note that this MCT 7-speed can handle considerably more torque and is not the same unit as the dual-clutch transmission found on the Mercedes-Benz SLS AMG[WIKI]
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