New SLK V6 Engine from Mercedes-Benz

Press Release

New SLK V6 Engine from Mercedes-Benz

Six cylinders for sporty roadster enjoyment

• Balancer shaft
• Direct ignition system
• New-technology hot-film air mass sensor
• Catalytic converters arranged in close engine proximity
• Aluminium crankcase
• Forged, four-bearing crankshaft
• Lightweight engine with weight-reduced pistons and connecting rods
• Linear lambda control
• Twin-cartridge air filter with integral resonators
• Engine-mounted control unit
• Infinitely adjustable intake and exhaust camshafts
• Oil/water heat exchanger
• Variable intake manifold with length control flaps and tumble flaps in the intake ducts
• Four-valve technology with roller-type rocker arms and hydraulic valve clearance adjustment
• Heat management with electronic mapped thermostat
• Cylinder liners in low-friction aluminium-silicon technology

A new model - a new engine: this combination is a rare occurrence in automobile development. Mercedes-Benz will be offering it in the coming SLK-Class from spring 2004. The newly developed sports car will enter the fray with an equally new engine which meets drivers' expectations of a powerful and lively roadster in all respects. No other V6 engine in this displacement class is able to offer output and torque characteristics which have been so specifically designed for dynamic performance and enjoyment as this new development by Mercedes-Benz, which also makes its mark in terms of fuel consumption, exhaust emissions and comfort. Output: the new 3498 cc six-cylinder engine develops 200 kW/272hp at 6000 rpm, corresponding to an output per litre of 57 kW/78 hp - an outstanding figure in this displacement class. The same applies to the torque: 350 Newton metres are already on tap from 2500 rpm and remain constant up to 5000 rpm. This guarantees fast acceleration and rapid sprints, but also relaxed driving in the lower gears - catering for the wishes of roadster fans who enjoy the occasional extended tour with the vario-roof open. And finally fuel consumption: 240 g/kWh is the value quoted by the engineers as the actual, specific fuel consumption at the best engine operating point. In practice this translates into an NEDC overall fuel consumption of less than ten litres per 100 kilometres, an exemplary figure for this performance class. These figures are the result of solid engineering work based on the enormous know-how and vast experience of the Mercedes engine development departments in Stuttgart-Untertürkheim. A team of around 500 engineers, technicians, mechanics, production planners and partners from the supply industry was involved in the development of the six-cylinder engine, and approx. 400 test engines have proved their worth on test benches and during practical trials in all the climatic zones of the world since the start of the project. From spring 2004 Mercedes customers purchasing the SLK-Class will be able to experience the qualities of the new V6 engine for themselves.

Focus on five development objectives: progress on a broad basis

Output, torque, fuel consumption, comfort and exhaust emissions - these were the equal-priority criteria on which the Mercedes engineers focused for the new V6 engine. They developed technical innovations which do not represent individual solutions, but rather have a positive effect in various areas. A survey of the major engine-related innovations and their importance for the output, torque, fuel consumption, comfort and exhaust emissions:

Fourfold camshaft adjustment to suit the engine load

The four-valve technology usual in a sports car engine and four overhead camshafts have already fulfilled some of the main criteria for an exemplary power curve, however this was not enough for the engineers in Stuttgart. In addition they developed a system which allows the interaction of the 24 valves to be controlled as required - as a function of the engine load - and ensures an ultra-fast charge cycle in the cylinders: variable and continuous camshaft adjustment. The innovative feature of this new development by Mercedes is that the angles of the two intake and exhaust camshafts can be continuously varied by up to 40 degrees, so that the valves are able to be opened and closed at the most favourable time in any driving situation. Under low engine loads the engineers use this technology to allow the exhaust gases to flow directly from the combustion chamber to the intake duct. During the process the camshafts are adjusted so that the exhaust valves remain open for a short time while the intake valves are opening. During this split second, some of the exhaust gases are able to flow from the exhaust duct to the intake duct. The partial vacuum in the intake manifold assists this process. This valve overlap when venting the exhaust gases and taking in the fresh mixture makes an efficient internal exhaust gas recirculation possible. This reduces the energy losses during load changes in the cylinders, leading to a significantly lower fuel consumption.