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New Mercedes C-class engines have 48V starter/alternator

By Graeme Roberts | 20 June 2018

New 1.5 with mild hybrid is in C200 versions

New 1.5 with mild hybrid is in C200 versions

Daimler's Mercedes-Benz Cars has launched a new generation of I4 petrol engines with the C-Class mid-life facelift, adding a 48 volt system with belt-driven starter/alternator to 1.5-litre versions in the C200.

Both versions, replacing a previous two-litre petrol I4, develop 135 kW/184 hp and 280 Nm. The 48V electric motor adds 10 kW and torque of 160 Nm.

Daimler said the combination of a 48 volt on-board network and EQ Boost creates the conditions for additional functions that help to reduce fuel consumption even further while improving agility and comfort characteristics.

When accelerating, EQ Boost can assist the engine, bridging the brief moment until the turbocharger has built up its full charge pressure. This boosting is also used to reach the engine's ideal rpm as quickly as possible during gearshifts. The shift time of the automatic transmission is shortened as a result. During deceleration, the starter/alternator recuperates kinetic energy and charges the battery.

The water pump is electrically driven and actuated by a characteristic map. This optimally adapts the cooling output to the current need.

Other advantages include the gliding mode with the engine switched off and recuperative braking with intelligent engine stop when the vehicle is coasting.

The start/stop system, using the belt-driven starter/alternator, restarts the engine almost silently with low vibrations and very rapidly, Mercedes claims.

Measures to reduce friction round off the efficiency strategy of the new I4. These include the patented Conicshape process, known in-house as conical honing.

When form honing the cylinder walls, the cylinder wall is opened out slightly towards the bottom, so as to reduce friction at the piston skirt for lower wear and fuel consumption.

Like the diesel engines, all petrol engines are equipped with a particulate filter in Europe.