Drive system: 4.0-litre V8 biturbo engine and SPEEDSHIFT MCT 7-speed sports transmission: V8 biturbo engine with hot inside V

Jun 3, 2016
Affalterbach

The 4.0-litre eight-cylinder biturbocharged engine is already used in the C 63 Saloon, Estate and Coupé. It is also installed in the GT sports car with dry sump lubrication. A characteristic feature is that the two turbochargers are positioned not on the outside of the cylinder banks, but between them in the "V" – experts call this the "hot inside V".

The main advantages of this design are the compact engine construction, optimal response and low exhaust gas emissions. The 'hot inside V' also optimises the supply of fresh air to both exhaust gas turbochargers. Electronically controlled blow-off valves ensure a very immediate and direct response. The maximum charge pressure in the C 63 S Cabriolet is 1.2 bar, and in the C 63 Cabriolet 1.1 bar. The turbochargers reach a maximum rotational speed of 186,000 rpm.

Direct injection with spray-guided combustion

A combination of biturbocharging and direct petrol injection with spray-guided combustion increases thermodynamic efficiency, thereby reducing fuel consumption and exhaust gas emissions. Particularly fast and precise piezo injectors spray the fuel at high pressure into eight combustion chambers. Multiple injection occurs on-demand, ensuring a homogeneous fuel/air mixture. The delivery of fuel is electronically controlled and fully variable for a fuel pressure between 100 and 200 bar.

Cylinder bore liners featuring NANOSLIDE® technology

The aluminium crankcase is produced using sand casting technology and features a closed-deck design. This ensures extreme strength while keeping the weight as low as possible, and allows high injection pressures of up to 140 bar. The NANOSLIDE® coating of the cylinder liners is also used in the Formula One engines of MERCEDES-AMG PETRONAS. It is twice as hard as conventional cast iron cylinder liners and therefore wear-resistant, and at the same time also reduces friction, thereby contributing to higher efficiency.

'Spectacle honing' is another measure to reduce friction and therefore consumption: in this complex process, the cylinder liners receive their mechanical surface treatment when already bolted in place. A jig resembling spectacles is bolted to the crankcase in place of the cylinder head mounted later. Any cylinder warpage that might occur during final assembly is therefore taken into account or eliminated as the cylinder liners are honed. This has advantages in terms of both durability and oil consumption.

Cylinder heads with zirconium alloy

The cylinder heads in the AMG 4.0-litre, V8 biturbo engine are made of a zirconium alloy for maximum temperature resistance and thermal conductivity. Four overhead camshafts control a total of 32 valves. Camshaft adjustment on the inlet and outlet side enables an excellent response and optimises the gas cycle for each operating point. Optimised valve springs and the low-friction valve gear with cam followers deliver further fuel savings.

In addition, forged aluminium pistons featuring a lightweight design and high strength are used. A low-friction piston ring package reduces fuel and oil consumption.

Efficient cooling of charge air, water and engine oil

For optimum power output even when outside temperatures are high, Mercedes-AMG uses indirect air/water intercooling. With optimum air and water flow, the intercoolers have a separate, two-stage low-temperature water circuit. The water-flow intercoolers ensure that the charge air compressed and heated to up to 140 degrees Celsius by the turbochargers is effectively cooled before entering the combustion chambers, and remains at a constant, low level of max. 25 degrees Celsius above the ambient temperature even under full load. A large radiator at the car's front end ensures controlled cooling of the water circulating in the low-temperature circuit. Extremely short charge-air ducting makes for optimum responsiveness.

The engine coolant is cooled on the particularly effective cross-flow principle, featuring two high-temperature radiators connected in parallel and a particularly efficient 1 kilowatt suction fan.

Since the water pump is driven by the timing chain, a simpler belt drive system with lower tension force is used. The advantage: less loss of drive power. With a rated flow of 420 litres, the water pump conveys the equivalent of more than two full bathtubs per minute.

An external engine oil cooler in the front apron helps to provide proper thermal management for the V8 engine. It is located in the front apron for aerodynamic efficiency. A two-stage, controlled oil pump circulates the engine oil. This varies the flow rate depending on load and engine speed requirement, thereby benefiting fuel economy. At high engine speeds more than 1.0 litre of engine oil per second flows through the oil lines and ducts. To save on weight, numerous oil and water lines are made of aluminium.

C 63 S with dynamic engine mounts as standard

Unique in its segment, the C 63 S Cabriolet – like the Saloon, Estate and Coupé – is equipped with dynamic engine mounts. These help to further resolve the conflicting aims of comfort and dynamic performance. These dynamic mounts are very quickly and variably able to adapt their stiffness to the driving conditions and requirements. Soft engine mounts improve comfort, as they provide more effective decoupling of noise and vibration. However, handling and agility benefit from a generally stiffer mount set-up. These measures enhance the vehicle's precision when driven dynamically. For example, the steering response and feedback are even more direct.

"One Man ‑ One Engine": a tradition of hand-built excellence

The biturbo eight-cylinder engine of the C 63 Cabriolet is fitted by hand in the hand-finishing section of AMG's production plant in Affalterbach based on the "One Man - One Engine" philosophy. This means that each engine is assembled by a highly qualified technician who applies the strictest quality standards. This technician is responsible for everything from installing the crankshaft in the engine block and assembling the camshafts to wiring the engine and filling it with engine oil ‑ as clearly evidenced by the signature on the AMG engine badge.

Electronic documentation of the entire production process

During the assembly process, each engine undergoes a series of tests in which it is examined for oil and water leaks. The entire fuel system is likewise checked for leaks ‑ to the extent that even individual gas molecules can be detected. All the engine functions are then examined on the "cold-test bench" using simulated resistances and pressurisation as well as the very latest resonance and airborne noise measurement methods. And finally a fully automatic image processing system is used to check the delivery condition of the completed engine.

In addition to this, the assembly process is controlled and documented by the AMG Trace System. This system allows full documentation of various process parameters such as the tightening torques, angles and curves of all bolted connections, fluid levels, component and batch information, and test results.

Faster gearshifts: the AMG SPEEDSHIFT MCT 7-speed sports transmission

The transmission plays a major part in the direct and sporty character of the new Mercedes-AMG C 63 Cabriolet. The AMG SPEEDSHIFT MCT 7-speed sports transmission impresses with its pronounced dynamics and high variability. Whether automatic or initiated by the driver using the steering wheel shift paddles, upshifts and downshifts are executed quickly and immediately. This is achieved by specifically adjusting the engine and transmission parameters. Furthermore, the aluminium shift paddles are now able to transmit the driver's commands to change gears even faster. The tangible driving dynamics are thus enhanced further.

AMG DYNAMIC SELECT transmission modes

The driver is able to influence the characteristics of the C 63 with four different AMG DYNAMIC SELECT transmission modes. The driver decides on the desired driving experience, from comfortable to super-sporty, using a controller to the left of the touchpad.

"Comfort" is the well-balanced transmission mode with a comfort-oriented suspension and steering set-up, as well as a fuel-efficient powertrain configuration – including smooth gearshifts and a discreet engine note.

The "sailing function" ensures a further reduction in fuel consumption: when the driver releases the accelerator in a speed range between 60 and 160 km/h, the clutch of the MCT transmission is disengaged and the engine is decoupled from the powertrain. The electronics reduce the engine speed to idle level, and the driving resistance is reduced by the compression and frictional forces of the engine in overrun mode.

"Sport" transmission mode is characterised by agile response to accelerator pedal input, shortened shift times and earlier downshifts. Gear changes are made significantly more emotionally appealing thanks to a double-declutching function when downshifting. On top of this, the steering and suspension feature more dynamic tuning. The experience becomes even more dynamic in "Sport Plus" mode. Numerous parameters are sharpened further here, from the highly agile throttle response and the acoustically more powerful double-declutching function, through to targeted torque control during upshifts with cylinder deactivation. The higher idle speed enables lightning-fast moving off. Suspension and steering are equally tuned for an even faster response. In addition, the exhaust system sound is more emotional.

The C 63 S has an additional "RACE" transmission mode. It is the optimal setting for tackling some ambitious laps on a closed-off race track. Here the drivetrain reacts extremely spontaneously and the ESP® switches to Sport Handling mode. In "Individual" transmission mode the driver can individually adjust the response of the drive system, suspension, transmission, exhaust system and ESP®.

Overview of the AMG DYNAMIC SELECT transmission modes:

Transmission mode

"Comfort"

"Sport"

"Sport +"

"RACE"

"Individual"

Drive system

C

S

S+

R

C, S, S+

Transmission

D

D

D

D

M, D

Suspension

C

S

S+

S+

C, S, S+

Steering

C

S

S+

S+

C, S, S+

Exhaust system

C

C

S+

S+

C, S+

ESP ®

On

On

On

Sport Handling Mode

On, Sport Handling Mode

ECO start/stop function

On

Off

Off

Off

Dependent on powertrain settings

"Sailing function"

On

Off

Off

Off

Dependent on powertrain settings

 

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