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1 Sequential multipoint portinjection of compressed natural gas (CNG) offers several advantages to CNG-engines. With the Trans-Valve-Injection system (TVI) a high speed gas jet is pulsed from the intake port through the open intake valve into the combustion chamber, where it causes effects of turbulence and charge stratification particularly at engine part load operation. The system is able to diminish the cyclic variations and to expand the limit of lean operation of the engine. The flexibility of gas pulse timing offers the potential advantage of lower emissions and fuel consumption. The TVI-System including special two-stage injectors was developed at Lucerne School of Engineering. In the present project this system was tested on a 2.8 litre natural aspirated CNG-IVECO-engine, at the Biel School of Engineering, Switzerland.