New Mercedes-Benz Euro-4 Diesel Engine: More Power, Same Fuel Consumption
27 December 2004
Mercedes-Benz is replacing its current in-line five and six-cylinder diesel engines with a new, more powerful 3-liter V-6 beginning in March 2005. The engine, with an output of 165 kW/224 hp and a maximum torque of 510 Nm (376 lb-ft), meets Euro-4 emissions limits.
This successor to the five and six-cylinder in-line engines increases output and torque up to more than 30% while maintaining fuel consumption at the level of its predecessors, according to Mercedes-Benz.
The engine features a number of developments—such as the mechanical design and engineering of the engine block and cylinders, enhancements in the fuel system, and enhancements in the engine control software—that highlight what can be done to make internal combustion engines more efficient. In this case, Mercedes is using its engineering prowess to enhance performance while maintaining current comparable levels of fuel consumption and CO2 emissions. While this engine could fill a downsizing role—i.e., replacing a larger, less fuel-efficient engine—that is apparently not the application path Mercedes is taking with this design, at least not initially.
The chart below compares the new V-6 to some older in-line 5- and 6- cylinder cousins used in current C270 and E320 models. Note the increase in engine output and performance for the V-6. (Note also the difference in fuel consumption between the two models of the E320—the difference between them being that one meets the more restrictive Euro-4 emissions limits.)
|Select Mercedes-Benz Diesels|
|Design||V-6||In-line 5||In-line 6||In-line 6|
|Fuel Consumption: l/100km
At 208 kg, the new V-6 is only slightly heavier than the previous 5-cylinder engine, mostly due to its aluminium crankcase with cast-in grey iron cylinder liners. The power-to-weight ratio has increased by more than 20% to 0.79 kW/kg.
Because the engine block, components and ancillary units form a very compact entity (the “one-box concept”), the new V-6 can be installed in Mercedes model series—such as the C-class—where no six-cylinder diesel engine was previously offered.
Newly developed piezo injectors in the common rail fuel system operate much more rapidly and precisely than the previous solenoid valves, and ensure a finely metered fuel supply to the cylinders. This allows the fuel injection to be even more precisely adjusted to the current load and engine speed, and now makes five injections per power stroke possible at a peak pressure of up to 1600 bar.
Electrically controlled intake port shut-off modifies the turbulence of the intake air as it enters the cylinders, optimizing the combustion process with the aim of further reducing the fuel consumption and exhaust emissions.
With the precise engine management system, the NOx and PM emissions of the V-6 engine conform to the limits of the Euro-4 standard. Two oxidizing catalytic converters are responsible for conversion of the carbon monoxide and hydrocarbons: a light-off converter located near the engine and a main converter in an underfloor location.
A maintenance-free particulate filter system is standard equipment for the V-6 engine in Germany, Austria, Switzerland and the Netherlands. The filter is purged 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, burning off the particulates trapped in the filter in a controlled manner.
Even without the particulate filter, PM emissions are less than the Euro-4 limit of 0.025 g/km.
More detail on the V-6 diesel is available in the Press pack, here.
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