Benz's new V6 and twin-turbo V8

Mercedes-Benz is set to roll out a new pair of V-formation engines in coming months -- and they will bring significant improvements in power, torque and fuel efficiency.

The S-Class flagship, traditionally the company's flag-bearer for new technologies, will arrive here in updated form before year's end, powered by the new engines in V8 and V6 configuration. First to arrive will be the primo coupe, which will lose its CL nomenclature and merely be known as the S-Class Coupe.

With the revised S-Class range scheduled for launch in Australia so soon, local buyers will see the new mills not long after their European release. And with a new CLS set for launch at the Paris motor show in October, the swoopy sedan will most likely reach us with the new powerplants around February or March 2011.

An insider at Mercedes-Benz has revealed it will also offer an AMG variant of the S-Class coupe, powered by a 5.5-litre version of the new V8. It and a subsequent AMG S-Class sedan will retain the 'S63' label, despite the reduction in capacity from the current 6.2 litres.

The changes to both V8 and V6 engines are substantial, taking in new multi-spark ignition systems capable of pitching up to four sparks per millisecond into the combustion chamber as new direct injection systems vary mixture intakes and combustion envelopes according to driving conditions and demands.

Reductions to internal friction, improvements to camshaft functions, more efficient internal lubrication and better coolant ducting all contribute to substantial improvements in overall operating efficiency for both V8 and V6.

The most marked changes take place in the eight (pictured). Twin turbochargers -- one for each cylinder bank -- have allowed Benz to reduce displacement from 5.5 to 4.5 litres and still boost power to 320kW (up 12 per cent from 285) and peak torque to 700Nm. This is up a huge 32 per cent from an already sizeable 530 Nm.

Benz was particularly keen to make as much of that twist available as early as possible. The existing engine serves up its peak at a low 1800rpm; the new one serves up 600Nm from 1600rpm up to 4750. That amounts to a 40 per cent hike in available Newtons from 2000rpm -- a rolled gold guarantee of a good time at the wheel for rocketeers and retirees alike.

The new V6 squeezes an extra 25kW of power (up to 225 from 200) and 20 more Nm of torque (up to 370 from 350) from the same 3.5 litre displacement as its predecessor. It remains naturally aspirated for the time being, but the company's new modular design and build methods leave the way open for the addition of turbocharging in the future if the manufacturer deems it necessary.

Benz claims considerable improvements in fuel economy and emissions for both. The new V8 sees combined-cycle fuel consumption drop from 12.3L/100km (in the existing CL500 coupe) to 9.5L/100km, with a commensurate reduction in CO2 emissions from the current 288 to 224g/km -- a 22 per cent improvement on both criteria. In the V6, combined-cycle fuel consumption has sunk to 7.6L/100km -- a 24 per cent improvement on the current V6's 9.8, while CO2 emissions drop from the current 234g/km to an impressive 177g/km.

Both engines feature a new stop-start system using sensors to register the attitude of the crank at the moment it stops, allowing it to select the most appropriate cylinder through which to set off ignition at restart. This boosts start efficiency and minimises strain on the starter.

As the Carsales Network has already reported, the cleaner engines will eventually also appear in the upcoming next-gen M-Class SUV. A notable addition from our insider was that the company is also working on a new oiler for that model -- and it won't be a six.

"There's going to be a four-cylinder diesel version... so 150kW and 500Nm four-cylinder..." he said.

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