MB S-Class In Depth

Press Release

Engines:
Peak performance in all disciplines

• Largest engine range in the luxury class
• New S 600 offers more power and torque than any other Mercedes car
• Twelve-cylinder engine develops 500 hp and 800 Newton metres
• 0 to 100 km/h in just 4.8 seconds
• Further improved V6 engine with eleven per cent more torque
• S 320 CDI with increased output and reduced fuel consumption
• Fuel consumption of just 7.7 l/100 km

The Mercedes-Benz S-Class boasts the largest engine line-up in this market segment, with no fewer than six state-of-the-art engines. These six-, eight- and twelve-cylinder engines set formidable standards on power, torque and fuel consumption. Most spectacular of all is the newly developed twelve-cylinder engine of the S 600, which incorporates all the skill and experience of the Stuttgart manufacturer in developing beefy high-tech power plants. Mercedes-Benz is the world's largest manufacturer of V12 passenger car engines: some 19,000 units of the predecessor Mercedes V12 engine have been supplied since 1999. With its twin turbochargers, water-cooled intercooler, three-valve technol-ogy , alternating-current twin-spark ignition and other high-tech innovations, the V12 engine develops power and torque which is unsurpassed in the luxury car market, with 368 kW/500 hp and 800 Newton metres of torque on stream at just 1800 rpm. Thus the new S 600 has over 36 per cent more power than the previous version, and around 51 per cent more torque. Mercedes-Benz offers the new twelve-cylinder saloon in long-wheelbase version only (3085 mm). The performance figures are as impressive as one would expect:

• Acceleration from 0 to 100 km/h: 4.8 seconds (previously: 6.3).
• Acceleration from 60 to 120 km/h: 5.2 seconds (previously: 7.5).
• Top speed: 250 km/h, electronically limited.

Comfort and emissions control to the highest standards Further outstanding features of the new Mercedes twelve-cylinder engine, besides formidable power and torque, include:

• Superb standards of refinement and low noise, thanks to the optimal 60 degree cylinder angle and the use of state-of-the-art design techniques.
• NEDC combined fuel consumption of 14.8 litres per 100 km -- an outstanding figure for a vehicle of this calibre and performance.
• Exhaust emissions conform to the EU 4 standard which will become law in 2005, thanks to the use of three valves per cylinder, twin-spark ignition, optimised injection technology and large-volume catalytic converters.

At a glance: vital statistics of the new V12 engine of the S 600 Modern, light-weight design using aluminium and special steel The crankcase of the V12 is made of die-cast aluminium, with die-cast magnesium used for the two cylinder head covers. Other lightweight components include "cracked" connecting rods made of forged, high-strength alloy steel, hollow-bore camshafts of inductively hardened forged steel, a weight-optimised forged steel crankshaft and a die-cast aluminium oil sump. Engine weight is thereby reduced to 263 kilograms, giving a power-to-weight ratio of 0.71 kg/kW. 800 Newton metres of torque on call at 1800 rpm The enormous power of the V12 engine is largely down to the twin turbo-chargers. Their cast steel turbines are space-savingly accommodated in the exhaust manifold, a position which allows them to develop maximum efficiency. The exhaust gas flow to the turbines is wastegate-controlled, in line with engine speed. The wastegate valves integrated in each turbo-charger are activated electropneumatically by the engine management system. The torque curve of the new Mercedes twelve- cylinder engine in the S 600 shows how effectively the fast-acting twin turbochargers do their job. Peak torque of 800 Newton metres comes on stream at 1800 rpm and remains constant through to 3500 rpm. The turbo- chargers develop a boost pressure of 1 bar. Maximum output of 368 kW/500 hp is developed at 5000 rpm. Twin-spark ignition with constant ion current measurement A high-performance microprocessor controls all engine functions, taking into account a wide range of parameters. The following sensors provide additional input for turbocharger control:

• pressure and temperature sensors in the intake air manifold for precise measurement of the intake air mass.
• a sensor upstream of the throttle valve adjuster for measuring current boost pressure.
• sensors upstream and downstream of the turbochargers for monitoring the pressure ratio, thus ensuring that the turbochargers do not exceed their maximum rotational speed.

The engine management also controls the state-of-the-art alternating-current twin-spark ignition (32 000 V), which features constant ion current measurement at the spark plugs. Using this technology, the engine management is able to identify misfiring and can take action to protect the catalytic converters. If the ion current falls below a certain value at a particular cylinder, fuel injection to that cylinder is automatically interrupted. Ion current measurement is also supplemented by torsional vibration sensing at the crankshaft. Together, the two signals provide the new V12 en-gine with a misfire recognition system of unprecedented accuracy which for the first time operates across the entire load and rpm range of a twelve-cylinder engine. Advanced intercooling system for maximised power output The air compressed by the turbochargers flows through two water-cooled intercoolers mounted on the cylinder head covers. Depending on engine load, the temperature of the compressed intake air can be reduced by as much as 100????????????????????C, thus optimising its temperature and density prior to combustion. The water-cooled intercoolers form part of a special low-temperature circuit in which an electric circulating pump transports heat as required between the intercoolers and a low-temperature water cooler mounted in front of the engine. Automatic transmission and rear differential adapted to the V12 engine To ensure that the high maximum torque of 800 Newton metres can be transferred without problem, the Mercedes engineers have made various modifications to the five-speed automatic transmission of the S-Class. The front planetary gear set has been widened by two millimetres and the centre and rear sets have been widened by five millimetres. This made it necessary to adapt the transmission input and output shafts, which are now twelve millimetres longer than before. In principle, the mechanical and hydraulic layout of the electronically controlled transmission remains the same however, as do gear ratios and gearshift operation. A new feature is the programme selector whereby the driver can choose between "S" (standard) and "C" (comfort) mode. This makes for even closer adaptation of the transmission characteristics to individual driving styles. In the "comfort" mode, the number of gearshifts is reduced and the transmission downshifts later. The driver can select a particular shift programme by pressing a button on the transmission tunnel trim. The drive shaft and rear differential have likewise been adapted to take account of the increased torque of the new S 600. The reinforced rear differential has a ratio of 2.65. V6 engine with 12.5 percent increase in power and torque The proven V6 engine of the S-Class has been further enhanced to give a substantial increase in power and torque. The piston bore has been increased from 89.9 to 97.0 millimetres, thereby increasing the displacement to 3.7 litres. This results in a 12.5 per cent increase in horsepower, which now reaches a peak of 180 kW/245 hp, and an increase of approximately eleven per cent in peak torque, to 350 Newton metres (at 3000 rpm). The various modifications have also had the effect of improving the dynamism, power delivery and refinement of the six-cylinder saloon, which now bears the model badge S 350. The new V6 S-Class accelerates from 0 to 100 km/h in 7.6 seconds, which is 0.6 seconds faster than the previous S 320, while its sprint time from 60 to 120 km/h is just 9.4 seconds. The S 350 has a top speed of 246 km/h, compared with 240 km/h for the previous S 320. Despite the increase in horsepower and performance, the fuel consump-tion of the new S 350 remains the same, at 11.1 litres per 100 km (NEDC combined consumption) -- an outstanding figure in this displacement class. Latest CDI technology brings four per cent fuel savings The dynamic six-cylinder S-Class diesel engine too will be entering the 2003 model year with increased horsepower and torque. At the same time it will also be more economical on fuel. Maximum output of this 3.2 litre powerplant has been increased from 145 kW/197 hp to 150 kW/204 hp and maximum torque reaches a new peak of 500 Newton metres at 1800 rpm (previously 470 Newton metres). The fuel consumption of the S 320 CDI has been cut by four per cent, to just 7.7 litres per 100 km (NEDC combined consumption). This advanced six-cylinder diesel engine is a second-generation Mercedes-Benz common-rail direct-injection engine. This latest generation in-corporates extensive modifications which result in significant improvements in torque, horsepower and fuel consumption. An increase in the maximum firing pressure from 145 to 155 bar, and an optimised gas cycle, result in improved low-end torque and responsive-ness. In the interests of a long operating life, the 10 bar increase in injection pressures is accompanied by various reinforcements to the connecting rods, the aluminium pistons, the crankshaft and the crankcase. Like the V8 diesel engine in the S 400 CDI, the six-cylinder unit too now features a VNT turbocharger with electric guide vane actuation. Electric actuation results in even more dynamic and even more precisely controlled turbocharging than with the previous pneumatic system. The guide vanes are actuated in accordance with an engine management programme, ensuring optimal operation of the VNT turbocharger in all driving situations. This results in faster development of boost pressure at lower engine speeds and thus in significantly increased torque. The effect of these measures can be seen in the impressive torque curve of the S 320 CDI: 250 Newton metres is on call at just 1000 rpm, and at 1400 rpm the engine is already delivering 420 Newton metres. This is some 85 per cent of its maximum torque of 500 Newton metres, which is supplied between 1800 and 2600 rpm. This helps to explain the impressive responsiveness and agility of this diesel model. The performance figures of the S 320 CDI also include a 60 to 120 km/h sprint time of just 8.1 seconds. Injection pressure increased to 1600 bar Thanks to even more precise, more efficient operation of the high-pressure common-rail injection pump, specific fuel consumption has been improved significantly, with NEDC savings of up to 0.3 litres per 100 km. An important feature of the second-generation common-rail direct-injection engines are the new seven-hole injectors, which allow the nozzle hole diameter to be reduced by about 20 per cent, thereby reducing the fuel flow by some 14 per cent. The effect is even finer fuel atomisation in the combustion chambers and better mixture formation. Above all, this brings a significant reduction in particulate emissions. However, if counter-measures were not taken, the greater throttling effect of the smaller injection holes would increase the injection period, which would have a negative effect particularly at high horsepower. In order to shorten the injection period, the injection pressure has therefore been increased from 1350 to 1600 bar. As on all common-rail engines, the injection pressure is available immediately at all times, i.e. even at low engine speeds. Twin pilot injections for quieter operation State-of-the art CDI technology also allows the engineers to achieve further reductions in noise. Instead of the previous single pilot injections - a measure adopted by Mercedes-Benz to compensate for the greater noise produced by direct-injection diesel engines compared with prechamber engines - twin pilot injections are now used. The high-performance sole-noid armature in the new 1600 bar injectors makes it possible to significantly reduce the interval between the pilot injections and the main injection so that now two successive small pilot charges can be introduced into the combustion chambers within the space of less than a millisecond, thus ensuring better preheating. The results are audible, with a further significant reduction in noise. The air filter too has been redeveloped. Its capac-ity has been increased by approximately 35 per cent, and pressure losses have been reduced still further. A wide-band noise damper in the air filter cover and the use of Helmholtz resonators in the boost air ducting have a further significant impact in terms of reduced engine noise. Output ratings from 204 to 500 hp With two six-cylinder engines, three V8s and a V 12, the S-Class offers a wider selection of engines than any other product in this segment. The output ratings extend from 150 kW/204 hp in the S 320 to 368 kW/ 500 hp in the range-topping S 600 model. The vital statistics are shown below: