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"In the design of new CI engines, it is of paramount importance to reduce the pollutants and fuel consumption," writes author Marco Nuti. In this, the first book devoted entirely to exhaust emissions from two-stroke engines, Nuti examines the technical design issues that will determine how long the two-stroke engine survives into the twenty-first century. Dr. Nuti, director of Technical Innovation at Piaggio, thoroughly explores pollutant formation and control from unburned hydrocarbon emissions, carbon monoxide emissions, catalytic aftertreatment, and secondary air addition.

After some general considerations about energy utilization by different types of vehicles when used in urban areas, the possibility of improving moped performances by means of simple carburation and engine modifications is evaluated. Positive results are achieved in this research and the show that decidedly the moped is at the first place as regards energy economy in urban areas transport. This implies that, in a short time, it will be available a class of vehicles which, besides offering energy utilization coefficients little lower than those of public transport vehicles, will be characterized by the advantages of individual transport and, moreover, will contribute to reduce traffic congestion in urban areas.

The Hi-Tech Two-Stroke SI engine is finding good appreciation in various fields of vehicle application and the final solution appears to include air assisted direct fuel injection and several solutions are now evaluated by the major world engine manufacturers. Those solutions anyway are poorly tailored to be fitted on very small engines such as for moped or light scooter applications both for the complications they require, consequentely the costs, and the difficult tuning of low load and idle caused by the very low quantity of fuel per cycle required. The proposed completely mechanical solution instead does consent with small modifications to the engine, only a new cylinder head is in fact required, to manage very well the engine all over its utilization range. After general considerations of the philosophy of the system and on the main parameters evaluation, a practical application on a 50cc scooter engine is described.