Mercedes has unveiled a new series of four-cylinder
diesel engines, the most powerful of which can deliver 150 kW from 2143
cc, a rise in power of around 20 per cent over the engines they replace.
At the same time peak torque has risen from 400 Nm to 500 Nm.
The engines will be making their first appearance in the C-Class from
this autumn.
Despite the increase in power the top-of-the-range engine uses less fuel
than its predecessor and CO2 emissions are 13 per cent lower, which means
that the engine already complies with the future Euro V legislation.
Fuel consumption is put at 5.4 litres/100km for the 150kW version and
5.1 litres/100km for the 125kW variant. CO2 emissions are 143 and 136
g/km respectively.
Mercedes-Benz Cars research chief Thomas Weber said: "This takes
our new four-cylinder unit into a realm which has so far been the preserve
of three-litre six-cylinder diesel or large V8 petrol engines."
The new engine is set to supersede four power units and will be fitted
across a range of vehicles, including the Sprinter van. It can be linked
to the Bluetec emissions control system that Mercedes is pioneering in
the US and will also be used as the power unit in hybrids.
The units have been under development for four years and have spent 100,000
hours in testing, with more than 10 million km.
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Features
• Two-stage turbocharging ensures high power output and optimum
torque delivery.
For details of the twin turbocharging system click here
• 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.
For details of the fuel injection system click here
• The maximum ignition pressure is 200 bar which also contributes
to the high output.
• Both the oil-spray nozzles and the water pump are activated
in accordance with requirements to save energy.
• The camshaft drive is positioned at the rear in order to
enhance running refinement and satisfy pedestrian protection requirements.
• The engine block is made from cast iron, the cylinder head
from aluminium.
• Two water jackets guarantee maximum cooling even at the
points of greatest thermal radiation; it is this that enables a
ignition pressure of 200 bar and such a high power-to-displacement
ratio.
• The aluminium pistons slide up and down in cast-iron barrels
for minimum frictional resistance.
• The connecting rods are made from forged steel, and their
weight has been optimised.
• In the interests of vibrational comfort, the forged crankshaft
with its eight counterweights turns supported by five bearings.
The radii of the crankpins are rolled for high strength.
• To compensate for the free vibration moments which are inherent
to four cylinder inline 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.
• A two-mass flywheel, featuring a primary flywheel mass fixed
to the crankshaft that is connected to the secondary flywheel mass
on the transmission by means of springs (technical term: spring-mass
system), isolates the crankshaft's vibration stimuli from the drivetrain,
thereby contributing to the engine's excellent smoothness. |
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