Mercedes released details of their new V8 and V6 engines, which as usual produce more power and use less fuel. But the amount of power these new powerplants develop in comparison to the ones they replace, is just incredible. You will find all the boring technical details about them right after he jump but in brief,the new 4.6 liter bi-turbo V8 has 435 hp instead of 388 hp of the current one, and the new 3.5 liter V6 puts out 306 hp instead of 272 hp.

As for the torque or pulling power as some people call it, the new V8 with an increase of 32 percent produces an astonishing 700 Nm (530 Nm for the old one), while the fuel consumption and CO2 emissions have fallen by 22 percent to 9.5 liters per 100 Km (from 12.3 liters) and 224 g/km.

The V6 too comes with more torque, 370 Nm (350 Nm for the last one), and it’s very economical as well as in a big S-class it can manage 7.6 litres per 100 kilometres and CO2 emissions of 177 g/km. That’s 24 percent better than the current V6 engines.

Innovative technology makes V6 and V8 engines fit for the future

Both the new V6 and the new V8 from Mercedes-Benz have aluminium crankcases, pistons and cylinder heads. The crankshaft, connecting rods and valves are of special forged steel.

Mercedes-Benz has achieved this considerable leap in efficiency with the use of innovative technology – including newly developed, third-generation direct petrol injection with spray-guided combustion, multiple injection and multi-spark ignition. With this new generation of V-engines, Mercedes-Benz is clearly demonstrating that with concerted further development, internal combustion engines still have a great deal of potential, and that V6 and V8 engines with their great running refinement are fit for the future.

The technology package in the new engine generation includes a number of new developments that are unique in this combination:

• In combination with multi-spark ignition, a further developed, third generation direct fuel injection system with spray-guided combustion and piezo-electric injectors offers further possibilities for fuel savings – in the V8 by means of an improved, homogeneous combustion process, and in the V6 by a new, stratified combustion process with a considerably extended characteristic map and fuel-efficient lean-burn technology.
• In conjunction with start/stop technology, shift point adjustment and specific friction-reducing measures, improvements in day-to-day fuel consumption by more than 20 percent are possible.
• Power consumption by ancillary units has been reduced. These include an optimised water pump with second generation thermal management, a demand-controlled oil pump, a volume-controlled high-pressure fuel pump and an intelligent generator management system.

Lightweight construction techniques and detailed improvements have also reduced in-engine friction considerably compared to the previous engine.

Third generation direct petrol injection

Direct petrol injection with spray-guided combustion, which Mercedes-Benz was the first car manufacturer to introduce in series production, has been developed further as a third generation. The system pressure is up to 200 bar, the pressure being variably optimised according to the engine’s characteristic map. Completely newly developed piezo-electric injectors allow up to five injections per intake stroke for the best possible mixture formation.

The crystalline structure of the piezo-ceramic changes in microseconds under an electric voltage, and with a precision of just a few thousandths of a millimetre. The central component of a piezo-electric injector is the piezo-stack, which directly controls the metering needle. With a response time of just 0.1 milli-seconds, the fuel injection can be very sensitively and precisely adjusted to the current load and engine speed, with a beneficial effect on emissions, fuel consumption and combustion noise.

The multiple injections even in tiny quantities made possible with piezo-electric injection technology were used by Mercedes-Benz engineers to control a wider characteristic map with the efficient lean-burn process, and to provide the conditions for further functions:

• As the first new operating mode, Mercedes-Benz engineers have developed “Homogeneous stratified combustion” (HOS). As the name implies, HOS is a combination of homogeneous lean-burn and classic stratified combustion. The first injection is sprayed into the intake stroke, forming a homogeneous basic mixture. Actual “stratified” injection takes place during the compression stroke before ignition, and is a single or double injection depending on the characteristic map.
• Another new operating mode is known as “Homogeneous Split” (HSP). In this homogeneous combustion process, more than 95 percent of the fuel is singly or multiply injected, followed a very small “ignition” injection to stabilise combustion. This is used when combustion conditions are difficult.

The characteristic map of the new Mercedes-Benz V6 engine is therefore basically divided into up to four areas:

– idling range (homogeneous)

– low partial load up to 4 bar and 3800 rpm (stratified)

– medium partial load 4 to 8 bar and up to 4000 rpm (HOS)

– high load and entire engine speed range (homogeneous or HSP)

The V8 engine is operated homogeneously over the entire characteristic map, but under high load homogeneous or HSP operation is used to improve smooth running characteristics.

Multi-spark ignition for optimal efficiency

The third-generation direct injection system also features rapid multi-spark ignition (MSI). Following the first spark discharge and a brief combustion period, the coil is rapidly recharged and a further spark is discharged. The MSI system enables up to four sparks to be discharged in rapid succession within one millisecond, creating a plasma with a larger spatial expansion than conventional ignition. Controlling this rapid multi-spark ignition enables both the time lapse before the next spark and the combustion duration for the relevant operating point to be optimally adjusted. This provides scope for optimising the centre of combustion and improving residual gas compatibility, especially during stratified charge operation. Fuel consumption can be reduced by roughly two percent in this way.

Fuel savings of up to four percent are possible alone by the use of piezo-electric injection technology in combination with multi-spark ignition, depending on the driving cycle.

Cylinder head with new camshaft adjuster

On the basis of the previous engine’s architecture, Mercedes-Benz engineers developed the variable, hydraulic vane-type camshaft adjusters for the intake
and exhaust sides. These now have a larger adjustment range of 40 degrees with reference to the crankshaft. They were also able to improve the functionality, achieving a 35-percent greater adjustment speed and adjustability at an oil pressure as low as 0.44 bar. Despite the better performance, this new development excels with significantly smaller dimensions and low weight. For this reason the installation space on the longitudinal and vertical axes of the engine was able to be reduced by around 15 millimetres.

Two-stage chain drive for low noise

The extreme compactness of the camshaft adjusters was achieved by the new, two-stage chain drive. This drives short secondary chains – one per cylinder bank – via a primary chain and an intermediate gear. All three chains can be individually adjusted via a chain tensioner. This results in low tensioning forces and low chain dynamics, ensuring consistent timing and outstanding acoustic properties, with friction reduced even further. In short, the new chain drive is compact and ensures low-noise operation.

Controlled oil pump with two pressure stages

A fourth chain drivers a likewise completely newly developed, variable vane-type oil pump. The operates with two pressure stages, depending on the characteristic map. At low engine speeds and loads the pump runs at a low pressure of two bar. At this time the oil-spray nozzles for piston cooling are switched off. The high-pressure stage is activated at the upper load and engine speed levels. Thanks to this control concept, the lubrication and cooling points of the engine can be supplied with significantly lower drive energy than would be possible with an uncontrolled pump.

New coolant ducting and 3-phase thermal management

The coolant ducting in the cylinder head is also completely new. The water mantle is of two-piece construction to improve flow. This leads to specific increases in flow speeds and heat dissipation at certain points, accompanied by a reduction in pressure throughout the coolant circuit. This has made it possible to reduce the power output of the water pump despite an increased engine output.

As it warms up, the flow of coolant is regulated by a 3-phase thermal management system so that it rapidly reaches normal operating temperature. Initially the coolant remains at rest in the engine. It then circulates in the engine circuit, but without the radiator. When a temperature of 105 degrees Celsius has been reached in normal operation (87 degrees Celsius under high load), the vehicle’s radiator is included in the circuit. The water supply to the interior heating system is separately controllable.

Component weights have also been reduced by the concerted replacement of aluminium and steel by plastics, e.g. for the thermostat, belt pulley, wheel, heater valve and hydraulic lines.

Start/stop function with direct-start

The new start/stop system operates with starter-supported direct-start. This means that when the engine is switched off, the attitude of the crankshaft is registered by a new crankshaft sensor so that the engine control unit knows the positions of the individual pistons. On restarting, it can then select the cylinder that has the most suitable piston position for first ignition. After the starter has briefly turned over the engine, reliable injection, ignition and combustion is immediately possible.

Minimised friction

Particular attention was paid to reduced friction in both engines. This was primarily achieved by a reduction in flow through the oil and water pumps, low-friction pistons, piston rings and cylinder walls, plus the new thermal management system and chain drive.

Fit for the future thanks to modular construction

The new V-engines from Mercedes-Benz are fit for the future. They can not only be combined with a start/stop function, but also coupled with the 4MATIC four-wheel drive system or integrated into a hybrid drive system.

The new engines meet all worldwide emissions regulations. The use of third generation, direct petrol injection with spray-guided combustion and piezo-electric injectors provides a particularly good basis for increased stringency in the future.