Changing the ignition advance angle has a significant impact on the performance of a combustion engine. Optimization of ignition advance angle is a major task of adjusting engine concerning emission standards, fuel consumption, torque value, etc. The results of the research showed that the process of optimizing ignition advance curve can noticeably increase engine efficiency, as well as torque and power output from the engine, while reducing fuel consumption as a result of lower indications of the air flow mass per second from MAF sensor (mass air flow sensor). The highest impact of the ignition advanced angle modifications can be seen in the area of the highest volumetric efficiency of the tested combustion engine. Almost no impact is observed within high engine speed levels. Simultaneously increasing engine load and rotation speed increases the possibility of engine knocking, which has devastating effect on engine durability.

Constant increase in number of vehicles and consequently significant contribution of transportation to air pollution level enforce actions leading to better assessment and emission reduction in urban areas. Advanced measurement stations are being located in key city zones to regularly monitor harmful substances concentration. As an alternative, computer modelling can be used for air quality assessment. This paper presents full process of modelling together with data preparation description. Road emission was evaluated by applying Network Emission Model (NEMO) to Legionow Square junction in Wroclaw, Poland. Geometry of study area was defined using GIS software, fleet structure was determined based on data from Intelligent Transport System (ITS) and emission factors were taken from HBEFA database. Simulation provided detailed data about transportation-related emission of various compounds, among which NO_x, CO, HC and PM are of the highest importance. Results were analysed both in terms of yearly summary and spatial distribution between traffic lanes. Simulation showed extensive emission of CO, PM and NO_x contributing to smog occurrence in Wroclaw. Opportunities for further improvements were discussed as well as the possibilities of applying it in planning systems and integration with dispersion models to develop complete air quality monitoring system for urban areas.

The depletion of the fossil fuels resources, significant increase of the air pollution caused by the use of internal combustion engines, and emission of carbon dioxide which is responsible for the greenhouse effect escalates the development of vehicle’s alternative drive systems. Generally, the emphasis is given to the alternative fuels (natural gas CNG, mixture of propane-butane gases LPG, hydrogen, alcohol fuels, biofuels) and hybrid or electric vehicles. Roads between large industrial and commercial centres, i.e. Wroclaw – Dresden – Prague, are used mainly by heavy-duty vehicles. Consequently, the contribution of the road transport to the ecological threat in this realm is significant. The objectives of this research were the assessment of the traffic volume and emission rate of exhaust gases caused by heavy-duty vehicles on the analysed roads and evaluation of the possibility of using existing and alternative drive systems in vehicles driving on the roads in the analysed region.

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Reliable modeling of emissions and dispersion of pollutants emitted in exhaust gases from motor vehicles is highly challenging due to the presence of multiple variables and inconsistencies in input data quality across different stages of the process. This article focuses on the vehicle fleet. It has been demonstrated that the structure of the vehicle fleet in a given area varies depending on the data collection methods and sources, which ultimately determines the dispersion results. This issue becomes particularly significant in urban environments, where the intensity of road traffic is high, and ventilation conditions are often poor, partly due to the formation of street canyons by dense urban development. The modeling was conducted at a selected intersection in Wrocław for various fleet structure scenarios. The results were compared with the results of pollutant concentrations from a nearby air quality monitoring station. The Copert emission model and emission factors from the European EMEP/Corinair database were used. In contrast, the GRAL model, a CFD model (suitable for urban dispersion modeling), was used to simulate pollution dispersion.