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A Look Back at Mercedes-AMG’s Mighty Turbocharged V8, the M157

After the success of the naturally aspirated M156, the Affalterbach engineers went back to forced induction for its successor. They previously took a similar route with the M113 K, pairing the stock M113 with a supercharger, but this time they decided to use a pair of turbochargers for the flagship V8.
Mercedes-AMG M157 V8 21 photos
Mercedes S 63 AMGMercedes S 63 AMGMercedes S 63 AMG M157 EngineMercedes S 63 AMG “Thirty-Five”Mercedes S 63 AMG “Thirty-Five” and 300 SEL 6.8 AMGMercedes S 63 AMG “Thirty-Five” and 300 SEL 6.8 AMGMercedes CL 63 AMGMercedes CLS 63 AMGMercedes CLS 63 AMGMercedes CLS 63 AMG M157Mercedes SL 63 AMGMercedes SL 63 AMGMercedes SL 63 AMG M157Mercedes E 63 AMG S-ModelMercedes E 63 AMG S-ModelMercedes E 63 AMG S-Model M157Mercedes GLE 63 AMGMercedes GLE 63 AMGMercedes-AMG M157 V8Mercedes-AMG M157 V8 with Transmission
Contrary to popular belief, the powerplant’s architecture is based on the M278 4.7-liter bi-turbo Mercedes-Benz unit, not the AMG-developed M156 it replaced.

Extensively reworked, its displacement was increased to 5.5 liters, mainly due to the upgraded piston bore and stroke of 98 mm × 90.5 mm (3.86 in × 3.56 in). Like the M278, it featured an aluminum block and cylinder heads, receiving a forged steel crankshaft and conrods connected to hypereutectic-cast pistons. The first piston rings had a diamond-like coating, a technology derived from the manufacturer’s racing engines.

The M157 was the first Mercedes-AMG V8 to use a direct fuel injection system. It had four valves per cylinder, each equipped with roller-type followers and by employing hydraulic cam adjusters, the powerplant benefited from fully variable valve timing. Furthermore, the exhaust valves were hollowed out and filled with sodium to optimize heat dissipation.

Mercedes\-AMG M157 V8 with Transmission
Much to the disappointment of conservative AMG fans who longed for the return of the mighty Kompressor units, forced induction was achieved with a pair of Garett MGT2260 MSL turbochargers capable of delivering a peak boost of up to 19 psi (1.3 bar).

For optimal operation at high rpm, a water-to-air intercooling system was utilized. However, the redline was only 6,400 rpm, which was lower than previous AMG V8s.

Similar to its M156 predecessor, it had a dry weight of 450 pounds (204 kg) and due to its compact construction, it was easy to fit in a wide variety of AMG-branded vehicles.

Although the displacement was well under 6.3 liters, the range-topping AMG models continued to be called 63s, purely for. marketing reasons. Except for the C 63, all of them were fitted with this new engine.

Mercedes SL 63 AMG
Depending on the model, the M157 had a wide range of output levels. The first units which were fitted to the S 63 and CL 63 produced 536 hp (400 kW) and 590 lb-ft (800 Nm) of torque. With the optional AMG Performance Package, power rose to 563 hp (420 kW) and 664 lb-ft (900 Nm) of torque between 2,500 and 3,750 rpm.

The tamest variants powered the 2012-2013 E 63 and CLS 63. Here, the engine delivered power is 518 hp (386 kW) and 516 lb-ft (700 Nm) of torque in standard form, or 550 hp (410 kW) and 590 lb-ft (800 Nm) on those equipped with the AMG Performance Package.

These two models got a power boost beginning with the 2014 model year that saw the output increase to 550 hp (410 kW) and 531 lb-ft (720 Nm) of torque or 577 hp (430 kW) and 590 lb-ft (800 Nm) of torque on the S-Model variants.

Mercedes E 63 AMG S\-Model M157
You can easily differentiate the Performance Package or S-Model units from the standard versions by simply lifting the hood. AMG fitted these rabid M157s with an exclusive carbon-fiber engine cover, instead of a plastic variant.

Regardless of the model, the engine was mated to an AMG Speedshift MCT 7-speed gearbox. This was essentially a 7G-Tronic that featured a wet clutch pack instead of a torque converter.

The engine debuted in March 2010 at the Geneva Motor Show where Mercedes-AMG introduced the SL 63 “Thirty-Five”, a tribute to the legendary 300 SEL 6.8 AMG “Red Pig race car. It was subsequently released with the 2011 model year S 63 and CL 63.

Mercedes S 63 AMG “Thirty\-Five” and 300 SEL 6\.8 AMG
It was produced until 2019, with the GLE 63 being the last AMG-badged model to receive it. The rest of the lineup began employing the new M177 4.0-liter bi-turbo that was more efficient and complied with the latest emission standards.

A naturally aspirated version dubbed M152 was released with the 2012 SLK 55 AMG. It shared many features with the bi-turbo version, including displacement or the direct injection system. It was rated at 409 hp (305 kW) and 398 lb-ft (540 Nm) of torque.

While it didn’t have the same immediate throttle response as its predecessor, the M157 was a solid performer that successfully helped Mercedes-AMG downgrade and provides a more efficient V8, without compromising performance or the famous exhaust roar that defined these high-performance vehicles.

 
 
 
 
 

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