Mercedes-Benz has revised their Series 300 and 400 engines so that they do comply with EURO 2 limits even prior to their coming into force in October 1996.
Comprehensive further development of the combustion process, turbocharging and of the entire fuel injection system has made it possible to comply with the exhaust limits while achieving optimal fuel consumption.
Multi-hole injection nozzles with small spray cross-section and appropriately matched injection pumps produce the high injection pressures necessary for low particulate emissions.
An electronically controlled variable stroke injection pump is used for achieving optimal fuel consumption on the Series 400, enabling the start of injection to be ideally matched to engine load, speed, temperature and operating altitude without the need for a mechanical injection timing device.
To remain within the economic remit, the aim in the case of the Series 300 was to meet the emission limits using a mechanically controlled injection pump. These engines are equipped with waste gate turbochargers for maximum power outputs to achieve good starting-off properties and a favourable torque curve in the lower engine speed range.
The strict US limits which come into effect from model year '94 are met by a specific further development of the in-line engines used in the future NAFTA area, with Mercedes-Benz do Brasil playing a major role in this development work. The various cycle-specific development strategies for European and American limits are compared and analysed.