Some interesting information from Bosch (www.bosch.com):

As a pioneer of diesel injection technology, Bosch offers a wide range of common-rail systems for diverse markets and applications. From two to twelve cylinders, for the Asian, European, and U.S. markets – Bosch has the right system in its portfolio for every kind of demand. Continuous improvements are making the diesel of the future even better in performance and more economical. “As Bosch sees it, the consumption of diesel engines can be reduced by another 30 percent in the future. Moreover, this can be achieved in compliance with increasingly strict emissions standards such as Euro 6 and the U.S. Tier 2 Bin 5,” says Dr. Markus Heyn, the member of the Diesel Systems division’s executive management responsible for the passenger-car business.

The modular concept of the CRS2 common-rail system with solenoid-valve injectors covers the range from two- to eight-cylinder engines. Apart from the tried and true CRS2-16 and CRS2-18 models, which deliver 1,600 and 1,800 bar respectively, the system is now also available in a CRS2-20 version, delivering 2,000 bar. Higher injection pressure vaporizes the fuel in the combustion chamber even more finely. This optimizes combustion, thus reducing emissions and fuel consumption. Moreover, in the newly developed CRI-20 solenoid-valve injector, an integrated high-pressure reservoir is used for the first time. This reduces fluctuations in pressure. All CRS2 injectors allow a wide dynamic range when controlling the nozzle needle, and thus make short intervals between injections possible. That allows up to eight individual injections per cycle. Advance injection reduces combustion noise and NOx emissions, and post-injection reduces particulate emissions. For some applications, the CRS2 common-rail system can already be designed to meet the Euro 6 emission standard, which will come into effect in 2014. Especially for the Asian growth markets, and in particular India and China, Bosch continues to offer its CRS1-14UP and CRS1-16, which are especially robust and cost-effective solenoid-valve systems featuring injection pressures of 1,450 and 1,600 bar.

The technically more complex CRS3 common-rail system with piezo injectors is designed for engines with very high specific power of more than 75 kilowatts per litre of displacement. It works in combination with the CP4 high-pressure pump and is so far available for system pressures of 1,800 and 2,000 bar. However, Bosch engineers are already working on systems with up to 2,500 bar. The piezo actuator develops some ten times more power than a solenoid valve, and is thus less sensitive to minor fuel impurities. For precisely metering the tiniest amounts for advance and post-injection, as well as for consistent quality over its service life, the inline piezo injector satisfies the highest standards. Thanks to its modular design, this system can be adapted to the requirements of engines with between four and twelve cylinders.