The Renault-Nissan Alliance’s new turbodiesel, the 1995cc 2.0 dCi, will make its debut in the recently updated Laguna model line later this month.
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The new engine will eventually be used in a number of Renault model lines. It is also likely to be shared with future European-built Nissan models – such as any replacement for the current slow-selling Primera – though Renault has not confirmed this. The engine will be made in several variants with different power and torque outputs.
The 2.0 dCi introduces a number of engineering upgrades with sophisticated internal aerodynamics to make the most of the piezoelectric injector capabilities, and advanced acoustics features.
Coupled with a new six-speed manual gearbox, the 2.0 dCi features four valves per cylinder, for a more even air-fuel mix. Intake and exhaust ducts are face-to-face across the cylinder head, with each camshaft operating intake and exhaust valves. This configuration improves cylinder filling and exhaust gas evacuation. Engine durability is enhanced by chain-driven valve gear and ancillaries.
The 2.0 dCi is fitted with a Bosch piezoelectric-controlled injection system.
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By GlobalDataPiezoelectric technology involves electrically energizing a stack of electrodes and ceramic wafers, producing an extension that lifts the injector needle. This technology affords very fast response times, for very fine control of the amounts of fuel injected.
This relatively new injection technology (also used on Toyota’s new Polish-made 2.2-litre turbodiesel) is claimed to gives very fast, very precise control over fuel injection. Response is up to four times faster than the older solenoid system, enabling engineers to opt for an injection cycle with five squirts: wo pre-squirts, one main squirt and two post-squirts. The pre-squirts improve engine acoustics by minimising the characteristic diesel clatter.
The post-squirts sustain the main injection combustion, to burn off soot and thus bring down pollutant emissions before the exhaust gases have even left the combustion chamber.
Another way to cut down pollutant emissions as early as possible is to tap off some of the exhaust gas leaving the combustion chamber and feed it back directly into the intake. The amount of recirculated exhaust gas is controlled by a valve that regulates the inflow on the basis of various engine parameters. This method produces a controlled temperature rise in the piezoelectric injector.
The pre-squirts preheat the combustion chamber to prepare for arrival of the main squirt and the post-squirts sustain combustion to burn off soot.
Acoustics was one of the engineering priorities for the new 2.0 dCi engine.
The engine block, with its aluminium bedplate, is designed for higher efficiency and improved vibration absorption. There are two balancer shafts turning in the opposite direction to the crankshaft, to cancel crankshaft rotary vibration. On high-power versions of the 2.0 dCi, this feature goes a long way to minimising the sort of vibration that typifies diesel engines, especially at high engine speeds.
Along with the pre-injection technique, this helps reduce vehicle interior engine noise levels.
All versions of the 2.0 dCi engine meet Euro 4 pollutant emission standards.
NOx and particulate emissions are minimised by very precise control over fuel injection, and various pre-exhaust pollution control systems. Low fuel consumption ensures the lowest possible CO2 emission.
The high-power version of the 2.0 dCi, developing a claimed class-leading175 bhp, have a periodic-regeneration particulate filter as standard.
When the filter fills up with soot particles, the engine runs a regeneration cycle, performing a second post-injection to deliberately overheat the exhaust gas. Above a certain temperature, the soot in the particulate filter oxidises off, and the cleaned filter can continue with its job of trapping particulates.
Later this month, Renault will launch the Laguna in some markets with a version of this new 2.0 dCi engine developing 150hp at 4000 rpm and torque of 340 Nm at 2000 rpm. With this unit, the Laguna will accelerate from 0 to 100 km/h (62mph) in 8.9 seconds, and cover 1000 metres from standstill in 30.3 seconds. Fuel consumption will be among the lowest in the category at this power range: 5.8 litres/ 100 km for a mixed cycle, and CO2 emissions of 154 g/km.
Development of the new engine required a total investment of €500 million, broken down as €200 million for engineering product/process, €250 million for industrial investments, and €50 million to suppliers.
It is made at Renault’s Cléon powertrains plant in Normandy. The new engine is combined with a new ‘PK4 gearbox’ made in the same factory.
This six-speed three-shaft manual unit, derived from the PK6 currently used with high-torque engines, introduces a number of new developments.
With its reinforced bearings and geartrains, the PK4 gearbox handles torques up to 360 Nm. A diecast aluminium casing gives low weight (54.5 kg dry) plus rugged resistance. And the PK4 also features a more compact spherical differential.
The PK4 also implements new engineering upgrades to minimise the noise characteristic of manual gearboxes. Acoustic resonance is reduced by using contoured housings, close to the shafts and gear trains. Reverse gear is synchromeshed, which means it can be engaged before the vehicle comes to a complete standstill.
