A new single turbo engine for PSA Peugeot Citroën

A new single turbo engine for PSA Peugeot Citroën
PSA Peugeot Citroën commissioned Bertrandt in France to develop all the mechanical components for its new DW12CTED4 engine. This 2.2 litre HDI engine with a single turbocharger produces 200 bhp, which makes it one of the manufacturer’s top-of-the-range models. At the same time, it meets the new Euro 5 emissions standard. We look back over all the stages of this exciting project.

How it all began
Right from the very beginning, it was clear that this project represented something completely new. For the first time, PSA Peugeot Citroën had decided to outsource the entire development and design process for the mechanical components of its new DW12CTED4 engine. The company chose Bertrandt to take responsibility for these challenging tasks. The goals of the project were ambitious: to design a single turbo engine, based on the twin turbo DW12BTED4, with improved performance and reduced fuel consumption that complies with the Euro 5 standard. PSA Peugeot Citroën plans to use the new engine in the 508 GT and the C5, but also in the Land Rover Freelander and the Jaguar XF250. For this reason, it had to produce 200 bhp. In addition, three variants of the engine had to be developed to meet the specific requirements of the four different brands: Peugeot, Citroën, Land Rover and Jaguar.

Complete component development

The team of Bertrandt component specialists and design engineers worked on the project from May 2007 to the end of June 2010. On the basis of PSA Peugeot Citroën’s functional concepts, they designed and developed the mechanical components of the engine which was to be the successor to the now discontinued DW12BTED4. The component specialists were responsible for the entire process of developing the parts: architecture, simulation, testing, costing and quality management. In addition, they had to meet all the specified criteria and ensure that the components reached production readiness on schedule. Furthermore, the components had to be designed for ease of assembly and manufacture. Other tasks which the design engineers took responsibility for included the design itself, the 3D plans, the calculation of the chain dimensioning and support for subcontractors who provided feedback on the parts.

A single turbo engine with the performance of a twin turbo
The Bertrandt engineers fitted the new water-cooled engine with a single lightweight turbocharger to ensure that its performance was equivalent to that of the DW12BTED4 twin turbo model. Subsequently, the exhaust manifold and turbo mountings were also redesigned to give the DW12CTED4 a new generation exhaust manifold. In order to avoid modifying the exhaust system as a whole, all the interfaces to the system were retained. After the design process had been completed, the package was created to enable the turbo to be fitted into the vehicle. As a result, the surrounding components, which included the turbo shield, the oil inlet and outlet pipes, the water feed, the coolant hoses and the manifold gasket, had to be modified for all three engine variants.

EGR module: highly efficient cooling

The combustion mechanisms were improved in order to ensure that the exhaust gas treatment process was as efficient as possible. The team at Bertrandt France focused closely on all the elements of the exhaust system, including the exhaust valves, the manifold and the exhaust turbo itself. The exhaust gas recirculation (EGR) module captures and cools a part of the exhaust gas and returns it to the combustion chamber. This is an essential element in the process of reducing the engine’s raw emissions. In collaboration with specialists from PSA Peugeot Citroën and the subcontractor, the Bertrandt team designed a highly efficient cooling system. A great deal of work was put into implementing the system. First of all, the components of the exhaust gas supply, recirculation and cooling systems were designed, together with the mountings.

Defining the architecture of the modules and choosing between a U-shaped or an I-shaped exhaust gas circuit in the heat exchanger presented further challenges. Ultimately, the U-shaped circuit was chosen, because it was the only solution that complied with all the functional and dimensional criteria. This design process took around six months. Finally, two EGR models based on two completely different concepts were designed to meet the differing requirements of the various vehicles: one for PSA Peugeot Citroën and Ford and another for Jaguar and Land Rover.

Crankshaft drive system: reducing energy losses and noise
The crankshaft, con rods and pistons are moving parts which make up the crankshaft drive system. The addition of a more powerful turbocharger necessitated the expectation of higher stresses being imposed on this system. With the aim of cutting CO2 emissions and fuel consumption, the component segmenting was improved in order to reduce the mechanical friction losses in the crankshaft drive system.

The torsional vibration damper was used to compensate for the changes in the inertial forces on the shaft assembly. The damper functions as an adjuster for the active inertial forces. Noise was transmitted through the end of the crankshaft in the previous version of the engine. Because the new engine is a premium model, the engineers at Bertrandt France decided to develop a special acoustic damping plug to resolve this problem. Incorporating the additional damping component presented challenges with regard to the process flow, because it was essential that it could be fitted easily.