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Bosch says that for Euro 5 and EEV applications it will offer a choice of two common-rail systems, both capable of delivering nozzle pressures above 2000bar. The less costly option is a "third generation" derivative of today's 1600/1800bar systems, but with a 2,200bar potential, says director of automotive business Bernd Bohr. Though its technical details have not been revealed, the systems are understood to be functionally similar to the XPI extra-high pressure common-rail system being developed  jointly by Scania and Cummins.

According to MAN director Dr Georg Pachta-Reyhofen - until recently head of engineering at the truck and bus subsidiary - the upgraded Bosch technology will be adopted on the company's D20 and D26 engines, enabling them to meet Euro 5 standards with EGR NOx control. Bosch's other new high-pressure common-rail offering, which is going into series production later this year, is destined for use in DaimlerChrysler's all-new HPEP (high performance engine platform) 9.9-, 12.8-, 14.8- and 15.6-litre heavy-duty in-line six-cylinder diesel family. It is the more radical APCRS (amplifier piston common rail system) which incorporates a 2.5:1 stepped piston intensifier serving each injector.

In its initial form it will deliver up to 2100bar at the nozzle from a modest rail pressure of only 840bar. Bohr explains that each injector's second solenoid actuator will not only "switch in" the intensifier when required it will also perform a rate-shaping  role, facilitating pre-, main- and post-injection events, allowing future stringent emission limits to be met with a minimum fuel consumption penalty. The first of DC's HPEP engines scheduled to feature the Bosch intensified common-rail system will be a Detroit Diesel-branded 14.8 litre unit, due to go into production at the group's Redford (Detroit) plant towards the end of 2007.

MAN evaluated but rejected this Bosch system, says Pachta-Reyhofen, on grounds of complexity, cost and bulk, especially installation height. The APCRS has the potential to deliver nozzle pressures of at least 2500bar, Bosch says.