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Downsized 5.5L V8 Biturbo in S 63 AMG Delivers 25% Fuel Savings Compared to Predecessor; Stop-Start is Standard

AMG 5.5-liter V8 biturbo engine. Click to enlarge.

AMG has developed a 5.5-liter V8 biturbo engine with a peak output of up to 420 kW (563 hp) and maximum torque of up to 900 N·m (663 lb-ft) from its higher performance variant for entry into the Mercedes-Benz/AMG lineup this summer. In addition to its twin turbos, the new eight-cylinder unit—known internally as the M 157—features gasoline direct injection with spray-guided combustion and twin turbochargers. The new AMG 5.5-liter V8 biturbo engine will play a major part in the Mercedes-AMG model strategy over the next few years, according to the company.

Debuting in the new Mercedes-Benz S 63 AMG, the new V8 biturbo consumes 10.5 liters per 100 kilometers (22.4 mpg US) (NEDC combined consumption, provisional figure)—a fuel savings of 25% compared to the current S63 AMG. An intelligently designed power transfer plays a major part in this: the unique AMG Speedshift MCT 7-speed sports transmission combines dynamism with economy, and includes a new stop-start function in the “Controlled Efficiency” driving mode.

“For the first time we have combined spray-guided direct petrol injection with turbocharging. With this high-tech package we are “best in class” with respect to fuel consumption, output and torque.”
—Friedrich Eichler, Head of Engine and Powertrain Development at Mercedes-AMG

The older AMG 6.3 liter V8 (which made its debut in 2005) naturally aspirated engine has a displacement of 6,208 cc, compared to the 5,461 cc of the new V8. For the first time, AMG is also utilizing the advantages of gasoline direct injection with spray-guided combustion and piezo-electric injectors: thanks to its higher thermodynamic efficiency, this technology makes more efficient use of fuel and leads to lower exhaust emissions. AMG combines this spray-guided combustion with twin turbochargers. Other highlights include an all-aluminum crankcase, four-valve technology with adjustable camshafts, an air/water intercooler, generator management and the standard stop-start function.

The AMG 5.5-liter V8 biturbo engine develops a peak output of 400 kW (544 hp) and maximum torque of 800 N·m (590 lb-ft). In conjunction with the AMG Performance package these figures are increased to 420 kW and 900 N·m. The major difference between the two performance classes is an increase in the maximum charge pressure from 1.0 to 1.3 bar.

With the provisional NEDC fuel consumption of 10.5 L/100km, the new S 63 AMG is 3.9 liters more economical than the preceding model powered by the naturally aspirated AMG 6.3-litre V8—despite an increase in output by 14 kW (19 hp) and 34 kW (46 hp) and in torque by 170 and 270 N·m for the base and performance package engines respectively. CO2 emissions have likewise been significantly reduced: at 246 grams per kilometer, the figure is 28.5% lower than for the previous model.

Taking into account the enormous performance and torque figures, the new AMG 5.5 liter V8 biturbo engine is in parts relatively twice as efficient as many mid-segment or compact-class diesel engines, according to AMG. The 5.5L V8 has a weight/power ratio of 0.41 kg/hp for the basic engine, and 0.39 kg/hp with the AMG Performance package.

The high-performance sedan accelerates from zero to 100 km/h in 4.5 seconds, and has an electronically limited top speed of 250 km/h (155 mph). The 100 km/h mark is reached in 4.4 seconds with the AMG Performance package, with the top speed increased to an electronically limited 300 km/h (186 mph).

The flat torque curve ensures enormous pulling power in all speed ranges: 670 N·m are already available at 1500 rpm, and the maximum torque of 800 N·m is delivered 500 rpm later, remaining constant to 4500 rpm. With the AMG Performance package, the engine delivers 875 N·m of torque at 2000 rpm, with a constant 900 N·m available between 2500 and 3750 rpm.

MCT 7-speed sports transmission with Controlled Efficiency mode and stop-start function. Power is transferred by the AMG Speedshift MCT 7-speed sports transmission used exclusively by AMG. The wet start-up clutch replaces a conventional torque converter, and helps to save fuel. The improved fuel economy is also in large measure due to the standard stop-start function. This system is active in the transmission’s Controlled Efficiency (“C”) mode, and switches the eight-cylinder engine off when the car comes to a stop. In C mode the sports sedan always starts off in second gear, and the transmission shifts to the next, higher gears at an early stage. With its high torque at low engine speeds, the V8 engine encourages a smooth, effortless driving style.

The eight-cylinder biturbo engine also features the generator management system from the E 63 AMG: whenever the engine is on the overrun or when braking, kinetic energy is used to charge the battery rather than being wasted as heat in the usual way. In all other operating modes a combination of onboard network and generator management enables the generator to be kept at a low voltage. This reduces the load on the engine and makes for fuel savings of around 0.15 liters per 100 kilometers according to the NEDC standard, and up to 0.2 L/100 km in city traffic with its frequent overrun and braking phases.


Stan Peterson

This is an article written about a transmission's mileage savings. But it is written as if the engine was responsible for the changes.

I love the hypocrisy. If this press release were offered by an American car company, the hoots of derision for the putative savings from an enormous V8 engine, would have been deafening. But since its was released by the, oh so Eco-conscious Germans, there is nothing said about it.

Fact. American cars are cleaner than German ones. Fact. American air is cleaner than Europe and Germany.
Fact. American air continues to get cleaner.
Fact. Europe's air gets dirtier with dirty diesels.
Fact. American air is reduced in CO2, Europe is not.


Sure, it's a huge V8 (although not a diesel), but did anyone expect Mercedes to introduce their next generation of engines on an entry-level car?

At least this way the customers who are asked to do the final bit of R&D and QA probably have something else to drive while the AMG's in the shop.

It's good that MB has finally cottoned-on to downsizing (the term is relative), turbocharging, and direct-injection.

I wonder what they mean by "(it) is in parts relatively twice as efficient as many (...) diesel engines."


I also love this quote from their press release:

"This equates to a fuel saving of more than 25 percent, which engine specialists consider to be nothing less than a quantum leap."

I guess nobody ever told them that, by definition, there is nothing less than a quantum leap.

Will S

More time spent rearranging the deck chairs on the Titanic for the spoiled class who remain addicted to oil...


Look at how many miles the "spoiled class" accumulate. If there are 100s of executive jets logging millions of miles versus 10s of 1000s of commercial jets logging billions of miles..who is doing the most damage?

Will S

It all adds up...


Sure it does, but when one factor out weighs another by a factor of 100 to 1, I tend to focus on the larger number.

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