C-class gets the best of BlueEFFICIENCY engines
Mercedes-Benz has been trying hard to build the best four-cylinder diesel engine in terms of power output and torque vs. fuel consumption and exhaust emissions. They say that they managed to get closer to such goal with the recently boosted 2.1-liter common-rail turbo diesel unit, outputting 25 kW more power.
The new 4 cylinder engine from the Untertürkheim plant in its most powerful variant produces 204 HP (150 kW) from its displacement of exactly 2.143 cc.
Mercedes-Benz is especially proud of the power-to-displacement and torque-to-displacement ratios, quoting figures of 95.2HP (70 kW) and 233.3 Nm per litre respectively.
Being the most powerful series-production engine in terms of specific power and torque, this engine immediately found its application in the the new C 250 CDIBlueEFFICIENCY, where it burns 5.1 liter of diesel per 100 kilometers.
Directly related to fuel efficiency is the eco-factor and the new Mercedes-Benz powerplant already meets the future EU5 emission standard.
I'm wrapping-up this news story with the quote from Mercedes-Benz's press release that fairly expands the above story with insightful technical explanations. Here it goes.
Let's not get carried away here with Mercedes-Benz sweet talk. First I'd like to remind you about VW Passat BlueMotion which burns only 4.4 l/100 km of the same fuel inside the 77kW 1.6 TDI unit. Now you understand why Mercedes-Benz is carefully choosing words. Specific power output tells us something about the power efficiency, i.e. the amount of power the engine is extracting out of the certain engine displacement. Mercedes-Benz is not saying that they are the most successful engine maker when it comes to downsizing. In a year or two, they might be repeating this success, maybe with some 1.5 diesel engine. We'll have to wait and see about that.
Speaking of C 250 CDIBlueEFFICIENCY, Mercedes-Benz wouldn't like to brag about the acceleration, but I'm sure it must be very, very good at this task, simply because the additional 25 kW’s always comes handy for zippy acceleration.
Meanwhile VW quotes Passat's 0-100 km/h time of 12.5 seconds and the top speed of 193 km/h.
The principal features of the new Mercedes diesel engine:
- Two-stage turbocharging ensures high power output and optimum torque delivery.
- Fourth-generation common-rail technology with a rail pressure that has been increased by 400 bar to 2000 bar, plus a new piezoelectric injector concept featuring direct injector needle control creates the ideal basis for more flexible injection timing, leading to smoother engine running, lower fuel consumption and reduced emissions.
- The maximum ignition pressure of 200 bar also contributes to the high power-to-displacement ratio.
- Both the oil-spray nozzles and the water pump are activated in accordance with requirements to save energy and therefore fuel. The oil pump's controllable design additionally reduces the oil flow rate - and therefore fuel consumption.
- The camshaft drive is positioned at the rear in order to enhance running refinement and satisfy the exacting pedestrian protection requirements.
- The engine block is made of cast iron, the cylinder head of aluminium.
- A two-part water jacket in the cylinder head ensures maximum cooling in the area of the combustion chamber plate; it is this that enables an ignition pressure of 200 bar and such a high power-to-displacement ratio.
- The cast-iron cylinder barrels have been more finely honed than in the preceding model, helping to improve consumption.
- To compensate for the second-order forces which are inherent to four-cylinder in-line engines there are two Lanchester balancer shafts at the bottom of the engine block running in low-friction roller bearings rather than conventional plain bearings.
- The two-mass flywheel has been specifically designed for high engine torque at low engine speeds in order to isolate the crankshaft's vibration stimuli, thereby contributing to the engine's excellent smoothness.
