New Engines for the New Mercedes-Benz S-Class

S Class new V8 petrol engine

World premiere of a new V8 unit - V6 and V12 engines

August 12, 2005 8:02 PM
Filed Under: German, Mercedes-Benz

Press Release

Overview

 

World premiere of a new eight-cylinder unit - V6 and V12 engines with considerably more output and torque

 

The engines for the new Mercedes-Benz S-Class are new or further developments which offer up to 26 percent more output and up to 15 percent more torque then the preceding series. Fuel consumption is reduced by up to nine percent. In autumn 2005 a new 5.5-litre eight-cylinder engine developing 285 kW/388 hp will celebrate its world premiere together with the luxury saloon. The range of outputs from the engines in the S-Class will extend from 173 kW/235 hp in the S 320 CDI to 380 kW/517 hp in the twelve-cylinder S 600.

The newly developed eight-cylinder unit is the top model in the new generation of Mercedes-Benz V-engines which was successfully introduced in mid-2004. Equipped with four-valve technology, variably adjustable intake and exhaust camshafts, a two-stage intake module and tumble flaps in the intake ducts, the new V8 is among the most powerful yet economical engines in its displacement class. Maximum torque is also significantly improved compared with the previous V8 engine; it has increased by around 15 percent to 530 Newton metres, and is available within a wide engine speed range between 2800 and 4800 rpm. As a result the eight-cylinder powerplant offers driving pleasure more typical of a sports car. The new S 500 accelerates from zero to 100 km/h in 5.4 seconds (previous model: 6.3 seconds).

Despite the 26 percent higher output, the NEDC (combined) fuel consumption remains at the level of the preceding model at 11.7 to 11.9 litres per 100 kilometres.

Technical highlights in the new eight-cylinder engine also include special shifting camshafts. These reduce the inherent pressure fluctuations in the exhaust train and thereby considerably improve the engine's gas cycle. This makes itself felt among other things by smoother running and higher torque in the lower and medium engine speed ranges.

The new Mercedes eight-cylinder employs the latest lightweight construction principles, with an aluminium crankcase, low-friction cylinder liners of aluminium/silicon alloy, a forged steel crankshaft and weight-optimised connecting rods. In addition to internal exhaust gas recirculation and secondary air injection, Mercedes-Benz uses two close-coupled catalytic converters with linear oxygen sensors to ensure low exhaust emissions. Thanks to its up-to-date engine technology and efficient emission control system, the new eight-cylinder engine complies with the most stringent exhaust emission standards now in place, and also has the potential to meet the limits planned for the future.

V6 engine with nine percent lower fuel consumption

The two six-cylinder engines for the new S-Class are likewise new developments. The S 350 is powered by the 200 kW/272 hp V6 engine which entered series production in mid-2004. Compared to the previous V6 petrol engine in the S-Class, the new high-tech power unit delivers around eleven percent more output, while saving one litre of fuel per 100 kilometres. The combined NEDC fuel consumption is 10.1 to 10.3 litres per 100 kilometres. The new S 350 accelerates from zero to 100 km/h in 7.3 seconds, and is therefore 0.3 seconds faster than its predecessor.

New six-cylinder CDI engine and more powerful twelve-cylinder unit from the beginning of 2006

From the first quarter of 2006 the new 173-kW/235-hp V6 diesel engine will be added to the range available for the S-Class. This supersedes the previous in-line six-cylinder unit of the S 320 CDI, improving output by 15 percent. Maximum torque is increased from 500 to 540 Newton metres, which is available between 1600 and 2800 rpm. This up-to-date direct-injection diesel unit is equipped with third-generation common-rail technology. Its advanced features include rapid and precise piezo-injectors, as well as a maximum injection pressure of up to 1600 bar. The maintenance-free particulate filter developed by Mercedes-Benz is standard equipment in the new S 320 CDI in a number of countries.

The new top model in the S-Class will also become available from the beginning of 2006. Thanks to an improved biturbo engine the twelve-cylinder S 600 Saloon develops an output of 380 kW/517 hp -12 kW/17 hp more than previously. Maximum torque increases from 800 to 830 Newton metres.

Mercedes-Benz equips the V6 and V8 models in the new S-Class with the unique 7G-TRONIC seven-speed automatic transmission as standard.

Details

 

The engines in the new S-Class: Strong performance

The engine is the heart of a car. And to make sure that this heart beats strongly over a long working life, the engineers at Mercedes gave it their particular attention during the development of the new S-Class: all the engines in the Mercedes flagship series are new or further developments. They develop more output and torque than the engines in the preceding series, operate even more smoothly and meet the most stringent worldwide exhaust emission standards.

In other words: whatever the choice of engine to power the new S-Class, its heart will certainly be strong and healthy.

The range of petrol engines comprises three power units with six, eight and twelve cylinders. At the lower end of this range is the new V6 engine with 200 kW/272 hp, which Mercedes-Benz has also offered in other car model series for a number of months. The message of this up-to-date six-cylinder unit is: more power, yet lower fuel consumption. Compared to the previous V6 in the S-Class, the new engine develops around eleven percent more output (up 20 kW/27 hp) and consumes nine percent less fuel in the NEDC test (down 1.0 l/100 km/h).

In addition to the latest 24-valve technology and four variable camshafts, this is considerably aided by the unique 7G-TRONIC seven-speed automatic transmission, which is standard equipment in the V6 and V8 models.

From the first quarter of 2006 the top-of-the-range model will enter the lists with an improved twelve-cylinder biturbo engine. Its output has increased by 12 kW/17 hp to 380 kW/517 hp, while the maximum torque has improved further from 800 to 830 Newton metres. The engine already makes this high torque available from 1900 rpm and maintains this level to 3500 rpm.

The eight-cylinder engine in the S 500 is a new development which will celebrate its world premiere in autumn 2005, together with the new S-Class. This power unit develops 285 kW/388 hp from a displacement of 5.5 litres, an increase of more than 26 percent versus the previous V8. At 530 Newton metres the torque also comfortably exceeds the maximum for the preceding engine by around 15 percent. This high level of torque is available from 2800 rpm and remains constant throughout a wide engine speed range up to 4800 rpm. Ideal conditions for powerful acceleration and fast intermediate sprints:

The fact that the combined NEDC fuel consumption of 11.7 to 11.9 litres per 100 kilometres has remained at the level of the preceding model despite a higher output and more torque clearly demonstrates the efficiency of the up-to-date concept and high-tech features of the new Mercedes eight-cylinder unit.

With a specific fuel consumption of 233 grams per Kilowatt hour (g/kWh) at the best point in its characteristic map, and 345 g/kWh at part-throttle (2000 rpm, 2 bar), the engine has easily the lowest fuel consumption in this displacement and output class.

Key data for the petrol engines in the new S-Class at a glance:

 

S 350

S 500

S 600*

Cylinder arrangement/valves per cylinder

V6/4

V8/4

V12/3

Displacement cc

3498

5461

5513

Dist. between
cylinders mm

106

106

90

Bore/stroke mm

92.9/86.0

98.0/90.5

82.0/87.0

Compression ratio

10.7 : 1

10.7 :  1

9.0 : 1

Output kW/hp

200/272

285/388

380/517

Max. torque                 Nm at rpm

350
2400-5000

530
2800-4800

830
1900-3500

*Available from first quarter of 2006

Powerful eight-cylinder unit as the highlight of a new engine generation

With the eight-cylinder unit for the S 500, Mercedes-Benz is presenting the top power unit in its new generation of V-engines, which was successfully introduced in mid-2004. This engine is produced in tandem with the six-cylinder engine of the S 350, at the DaimlerChrysler location in Stuttgart-Bad Cannstatt. This means that both engines belong to a single family and therefore share the attributes that make them prime examples of modern engine technology:

In order to achieve these five development goals and exceed the previous standards, the engineers in Stuttgart developed an extensive technological package. Its components interact perfectly, complement each other in their effects and thereby achieve remarkable progress in every aspect.

Lightweight construction for smooth running and dynamic agility

A crankcase of diecast aluminium with low-friction aluminium/silicon cylinder liners is the solid and durable basis of the new Mercedes eight-cylinder engine. It houses a five-bearing, forged steel crankshaft with induction-hardened main and big-end bearings. The connecting rods are also of forged steel, with specific areas milled away to make them around one fifth lighter than those of the previous V8 engine for the S-Class.

Saving weight was not the only important aspect during the design work on the new engine, however. The engineers were just as determined to achieve the best possible results where smooth running and flexibility are concerned. Lightweight construction principles were helpful in this respect, for the lower the moving masses in the crankcase, the lower the vibrations and the more responsive the engine is to movements of the accelerator pedal.

The new eight-cylinder unit does not require a balancer shaft to improve its smoothness, for unlike in a V6 engine, a cylinder angle of 90 degrees is ideal for the vibration characteristics of the eight-cylinder powerplant.

Shifting camshafts for a perfect gas cycle and higher torque

Mercedes engineers have already used an intelligent valve control system in the new V6 engine, achieving remarkable progress and a major contribution to the good performance characteristics and low fuel consumption of the unit. In addition to four-valve technology, continuously adjustable intake and exhaust camshafts ensure that the cylinders are optimally supplied with fresh mixture. The valves are opened at precisely the right moment in any driving situation, significantly improving the gas cycle in the combustion chambers and reducing energy losses.

The camshafts are controlled by electro-hydraulically operated vane-type adjusters, which are located at the forward ends of the camshafts and are controlled by four integral hydraulic valves. The intake camshafts are driven by a duplex chain, while the exhaust camshafts are directly driven by the intake camshafts via a braced pair of gears.

In the new eight-cylinder engine the engineers at Mercedes-Benz have optimised the effect of this four-fold, continuous camshaft adjustment by using what are known as shifting camshafts. These control the opening of the exhaust valves and improve the engine’s gas cycle even further. Depending on the ignition sequence, the exhaust cams are designed in such a way that the valves open at different times during the exhaust cycle. This reduces the pressure fluctuations in the exhaust tract which are inherent to a V8 engine, and which lead to an inconsistent residual gas content in the cylinders.

The valve lift interval on the exhaust sides of the new Mercedes eight-cylinder engine is as follows:

The newly developed shifting camshafts improve the torque and smoothness of the V8 engine by ensuring a more uniform residual gas content, a higher knock limit and better cylinder charging in the lower to medium engine speed range. At 2000 rpm, for example, the effective mean pressure is around six percent (10.3 : 11.0 bar) higher than in a comparable engine without shifting camshafts.

Two-stage intake module and tumble flaps for better combustion

In addition, the new V8 features the same technical innovations for situation-related control of the combustion processes that have already proved successful in the six-cylinder engine:

The tumble flaps, fuel injection, ignition and numerous other engine functions are managed by a powerful control unit, which also communicates and exchanges information with the other onboard control units in the new S-Class via a databus. In the interests of the shortest possible electrical paths the engine control unit is centrally located above the intake manifold and is integrated into the engine design. Combustion of the fuel/air mixture is by means of a direct coil ignition system. The spark plugs project into the centre of each cylinder between the four valves, with the ignition coils located directly above them.

Electronically controlled thermostat for situation-related heat management

The developers of the new Mercedes eight-cylinder engine have also made a major contribution to fuel economy with a sophisticated heat management system. Coolant circulation is interrupted during the warm-up phase, for example, so that the engine reaches its normal operating temperature more rapidly. This in turn improves the oil flow and considerably reduces friction in the engine. When the engine is warm and under full load, the heat flows are directed in such a way that the engine oil and coolant are always at an optimal temperature. This is ensured by an innovative, logic-controlled thermostat which is active in all operating situations and adjusts the coolant temperature according to the style of driving and the prevailing conditions. This also enables the heat supply to the heater core to be controlled as needed.

Twin catalytic converters und linear oxygen sensors for low exhaust emissions

The emission control system of the new Mercedes eight-cylinder engine follows a two-stage concept and is therefore highly effective. In addition to in-engine measures such as continuous camshaft adjustment, need-related combustion control by tumble flaps, internal exhaust gas recirculation and secondary air injection, which ensure low untreated emissions, the new S 500 is equipped with two close-coupled catalytic converters as standard. These consist of two individual monoliths or bricks, each of which is monitored by two oxygen sensors: a control sensor and a diagnostic sensor which analyses the exhaust flow in the gap between the two bricks.

This oxygen sensing is linear, which means that the oxygen sensors are already active immediately after a cold start, supplying information about the exhaust gas constituents for the electronic control unit of the V8 engine to process when controlling the warm-up phase. This enables the catalytic converters to reach their normal operating temperature more rapidly.

Thanks to its ultra-modern technology and efficient emission control system, the new eight-cylinder engine complies with the most stringent exhaust emission standards currently in force; it also has the potential to meet limits which are planned for the future.

Powerful six-cylinder diesel with latest-generation CDI technology

From the beginning of 2006 the newly developed CDI six-cylinder engine will join the range of engines for the S-Class. It has an output of 173 kW/235 hp, topping the figure for the engine in the preceding S 320 CDI by 15 percent. Maximum torque has increased by eight percent, from 500 to 540 Newton metres which are available between 1600 and 2800 rpm. These remarkable values make the direct-injection diesel unit one of the most powerful in its displacement class.

Combining this with the 7G-TRONIC seven-speed automatic transmission as standard ensures the best possible use of the outstanding output and torque potential in any driving situation.

Lightweight construction as a factor in exemplary diesel driving pleasure

The choice of materials, technical design, fuel injection and engine management system of the V6 diesel engine reflect the state of the art. for the first time with a diesel engine in this displacement and output class, Mercedes-Benz has developed an aluminium crankcase with cast-in grey iron cylinder liners for this unit, which makes a major contribution to weight reduction. As a result, the new six-cylinder engine weighs a total of only around 208 kilograms (acc. to DIN) and achieves a remarkable power-to-weight ratio of 0.83 kW/kg - a major contribution to the outstanding diesel agility offered by the new engine.

Key data for the V6 diesel engine in the new S-Class:

 

S 320 CDI*

Cylinder arrangement/ valves per cylinder

V6/4

Displacement cc

2987

Cylinder angle

72°

Distance between
cylinders mm

106

Bore/stroke mm

83/92

Compression ratio

18 : 1

Output kW/hp

173/235

Max. torque
Nm at  rpm

540 at
1600-2800 rpm

Fuel consumption Combined l/100 km

8,3-8,5 **

*Available from first quarter of 2006; ** provisional figures

Piezo-injectors for finely metered fuel injection

Third-generation common-rail direct injection is a further technical highlight of this engine. It produces significant improvements in terms of fuel consumption, exhaust emissions and combustion noise. Instead of the previous solenoid valves, the injectors are equipped with piezo-ceramics whose crystalline structure changes within milliseconds under an electric voltage. This lifts the needle jet at the tip of the injector with a precision of only thousandths of a millimetre and thereby achieves an extremely fine jet of fuel. Moreover, piezo injectors are considerably lighter and operate at twice the speed of conventional solenoid valves. With a response time of only 0.1 milliseconds, the fuel injection process can be even more precisely suited to the current load and engine speed situation, with favourable effects on emissions, fuel consumption and combustion noise. Five fuel injections per power stroke at a peak pressure of up to 1600 bar are possible thanks to this piezo technology.

An electrically controlled intake port shut-off modifies the swirl characteristics of the air flowing into the cylinders, which also optimises the combustion process with the aim of reducing the fuel consumption and exhaust emissions even further.

The likewise newly developed electronic control unit manages all the engine func-tions – from the quick-start glow system and automatic start function to control of the high-pressure pump. The VNT turbocharger (Variable Nozzle Turbine) with electrically adjustable turbine blades, exhaust gas recirculation with a control valve and intake air throttling are also regulated as the situation requires on the basis of measured data.

Catalytic converters and a particulate filter for emission values below the EU-4 limits

Thanks to this precise engine management system, the nitrogen oxide and particulate emissions of the V6 engine are within the strict limits of the EU4 standard. Two oxidising catalytic converters are responsible for conversion of the carbon monoxide and hydrocarbons: a so-called starting converter located near the engine and a main converter in an underfloor location. To reduce soot emissions even further, Mercedes-Benz offers a maintenance-free particulate filter system which is standard equipment in the new S 320 CDI in various markets. The filter regenerates without the use of additives by selective adjustment of different engine functions.

Depending on the operating parameters and filter condition, the variable third-generation common-rail technology allows up to two precisely coordinated post-injections with the aim of specifically increasing the exhaust temperature. This means that the particles trapped in the filter are burned off in a controlled manner.