da settembre la 407 completerà la gamma con 2 nuove motorizzazioni a gasolio: la prima è il già ben noto 2.7 V6 in configurazione 204cv (già presente sulla Coupè) mentre il secondo è un parziale inedito, si tratta infatti del 4 cilindri 2.2 litri al quale sono stati abbinati 2 piccoli turbocompressori montati con un sistema sequenziale-parallelo con il secondo che entra in funzione tra i 2600 ed i 3200 rpm. Potenza massima 170cv. Il nuovo sistema dovrebbe garantire una fluidità di erogazione superiore.

E sopra i 3200 torna a funzionare un solo turbo? A che pro?

Probabilmente per non spaccare tutto con una pressione eccessiva.

Sarà, ma a quel punto ha un picco di coppia ai medi regimi e poi si siede un pò, o no? Mica mi convince tanto la cosa

Trovo che per aver utilizzato un sistema così costoso, pesante, complicato e "nuovo" (in termini di affidabilità), la potenza raggiunta di 170cv e la coppia di 350nm siano troppo basse.

Come tutte... ma credo che in questo modo possa essere ridotto, infatti con la gestione elettronica delle wastegate il picco puoi gestirlo e con la doppia turbina puoi cominciare a "soffiare" prima e smettere dopo, rispetto ad una sola turbina.... un plauso agli ing. francesi...

E' sempre un errore "fissarsi" sul picco di coppia... sui diesel tradizionale e' molto appuntito (da qui l'effetto calcio)... magari la soluzione del doppio turbo permette di avere 350Nm per un numero di giri molto piu' consistente.

Si può fare tutto, quello che non capisco è come funzioni questo sistema. Un turbo è sempre in presa e un secondo funziona SOLO tra i 2600 e i 3200 (a meno che non ci sia un errore e si parli di 1600 al posto di 2600), quello che mi chiedo è quali vantaggi può dare un sistema del genere visto che si parla di sovralimentazione doppia per soli 600 giri. L'esclusione del secondo turbo agli alti regimi può anche starci, tanto saranno sicuramente turbo a geometria variabile.

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Improve power, refinement and economy

    *      New engine ? first to feature twin-turbochargers on a 4-cylinder diesel
    *      HDi 170 ? available in new 407 Sport models
    *      Latest advances in diesel technology improve power, refinement and economy

Peugeot, always at the forefront of diesel technology, is strengthening its position with the arrival of an exceptional new diesel engine to compete in the medium segment.

Saloon and SW models of the distinctive 407 range will soon be available with the advanced new 170bhp 2.2-litre HDi engine ? the first 4-cylinder engine to use twin-turbochargers, managed by a parallel sequential induction system.

The 2.2-litre HDi is an evolution of the existing 2.2 DW12 TED4 engine, and utilises the latest advances in diesel technology by combining power, refinement and excellent fuel economy. It is the fourth phase of the cooperation between PSA Peugeot Citroën and the Ford Motor Company (initiated in 1998).

The quest to deliver an outstanding state of the art diesel engine has resulted in the creation of a twin turbocharged, parallel sequential induction system that gives unrivalled levels of power and responsiveness, even at low revs. The first low inertia turbo operates up to 2,700rpm, and gives an immediate response to throttle input. As the revs rise, the second, smaller turbo kicks in seamlessly to give enhanced performance throughout the rest of the rev range.

The new HDi 170 is fully compliant with Euro 4 regulations, produces a maximum torque output of 277lb ft at only 1,500rpm and is mated to a six-speed manual transmission. The engine will be available in 407 Sport derivatives, and is priced at £21,100 OTR for the Saloon and £22,300 OTR for the SW version.
Technical Overview

    *      In line four-cylinder diesel engine with 16 valves (4 valves per cylinder)
    *      Direct injection with two fixed geometry turbochargers
    *      Bosch injection with piezoelectric injectors
    *      Two overhead camshafts (only the exhaust camshaft is driven by the timing belt)
    *      A high-pressure fuel pump driven by the exhaust camshaft



THE 2.2 HDi FAP ? DW12BTED4 ENGINE

The 4-cylinder engine has a capacity of 2179 cm3 with a 16-valve cylinder head and twin overhead camshafts.

Particular attention has been paid to the torque delivery and response times at low engine speed. At 1000rpm the engine develops 147lb ft of torque, and 206lb ft at just 1250rpm. In addition, the engine has a very wide operating range with excellent driveability through the rev range, attaining its maximum power of 170bhp at 4000rpm and a torque of 277lb ft from 1500rpm (54% more than the previous generation engine at the same engine speed).

A new type of combustion chamber, third-generation common rail increasing injection pressure to 1800 bar, and of course parallel sequential twin turbos are the main technological innovations.

The parallel sequential twin turbo

The technology of the parallel sequential twin turbo is a world first on a 4-cylinder car. The system (patented with Honeywell Turbo Technology) consists of two identical, smaller-diameter turbochargers. At low engine speeds, a single turbocharger ensures engine responsiveness. It is then supported by the second turbo, which starts to operate in parallel between 2600 and 3200rpm according to the required load and atmospheric conditions. The entire range of engine speeds is therefore covered. The system is controlled entirely by the engine Electronic Control Unit (ECU).

In addition, the low inertia and compact size of the turbo reduces turbo lag. These technological innovations enhance driveability, and in particular ensure excellent torque availability. Moreover, the driver can more easily drive at low engine speeds, thereby reducing fuel consumption.
ECCS combustion chamber (Extreme Conventional Combustion System)

In each of its pistons, the 2.2-litre HDi engine is equipped with an all-new combustion chamber. Compared to the previous generation, the chamber is characterised by a reduced compression ratio (16.6 compared to 18 previously) and a larger diameter (+25 %), helping to reduce the quantity of incompletely burned fuel by limiting the proportion of fuel in contact with the walls. This effect is obtained as a result of a special piston design and geometry (manufactured from aluminium with a very high mechanical strength and thermal resistance). This geometry also makes it possible to significantly reduce SWIRL (air movement in the combustion chamber) by limiting thermal losses against the walls.

These developments allow greater homogeneity of the air-fuel mixture, resulting in a significant improvement to the engine?s overall efficiency, as well as quieter combustion.
Third-generation common rail injection system

The ECCS combustion system is combined with an all-new, third-generation Bosch common rail injection system in which the injection pressure has been increased to 1800 bar (1350 bar for the first generation).

The higher injection pressure, associated with new piezo-electric injectors in which each nozzle is equipped with seven apertures (instead of five previously) with a diameter of 135 microns, allows the number of injections to be multiplied (potentially up to six per cycle) and ensures meticulous uniformity of the diesel injection spray pattern. As a result of this optimised air/diesel mix, combustion is more complete and more uniform, and therefore reduces emissions at source.
The environment

The new 2.2-litre HDi is a worthy standard bearer in terms of environmental protection. Firstly, it should be remembered that through its basic design, the Diesel engine ensures excellent thermodynamic efficiency and that HDi direct injection increases its performance still further.

Due to the very high pressure injection of the common rail system, the extremely fine spray of diesel fuel in the combustion chamber allows more uniform and more complete combustion, giving rise to more efficient combustion, which significantly reduces emissions at source.

In addition, the two turbochargers and the exhaust gas recirculation system contribute actively to environmental protection and observance of the EURO 4 standard.

Specifically, on the new 2.2-litre HDi, the combination of the new combustion chamber design with an injection pressure of 1800 bar results in a reduction of emissions of around 30% compared to the previous generation engine.

It is of course combined with the latest-generation DPFS (Diesel Particulate Filter System) technology featuring an additive-enhanced filter. This third-generation Octosquare particulate filter has a service interval on the 2.2-litre HDi of 120,000 miles. This interval has been made possible by improvements to the additive and the ceramic filter. The Eolys additive, with an enhanced effect that allows a smaller dose to be administered to the fuel, reduces the quantity of residue stored on the walls of the filter. The filter has a new structure in which the Octosquare geometry and larger diameter inlet ducts significantly increase the residue storage capacity.
Compact size

Compared to the previous generation engine, the overall height of the engine has been reduced by 4 cm. This highly compact engine allows greater adaptation into other vehicles and also improves the protection of users (particularly pedestrians) by creating a larger space between the bonnet and the engine block. Creating greater space under the bonnet ensures better energy absorption in the event of an impact.

The double-wall cylinder block, patented and produced entirely in the Trémery foundry, improves the engine?s acoustic performance by 3dB, a level which is a significant improvement and will be appreciated by customers.
Service

A large capacity two-part oil sump allows the oil change interval to be increased to 20,000 miles. Similarly, the drive belt and its engine accessories are designed and dimensioned to be maintenance-free during the life of the vehicle.
THE ML6C MANUAL GEARBOX

The 407 2.2-litre HDi engine is coupled with the 6-speed ML6C manual gearbox, highly acclaimed for its smoothness of operation, precision and swift gear changes.

Its compact size, one of its most striking characteristics, means it requires no more space than a 5-speed gearbox, so preserving the turning circle radius.

Ah, ecco, mi pareva... adesso sì che quadra tutto

Beh... era chiaro 

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Direi proprio di si

e sono turbine a geometria fissa, più affidabili. Mi pare una buona idea, complessivamente.