Some aspects of thermal load and operating indexes after downsizing for internal combustion engine

The twenty-first century started with many downsizing applications. This important trend in the engine technology has been constantly developed. There are questions about limits and on the other hand new solutions in the face of new materials, tribological discovery, lubrication oils, turbo- or supercharging, new control electronic system of the engine run, higher accuracy in designing, etc. Some of parameters of thermodynamics of working cycle and thermal load according to the downsizing engine parameters were considered in this article. The downsizing impacts on fuel economy and emission were analysed, too. The investigations were carried out with own measured data (i.e. pressure inside inlet manifold, temperature of engine wall) as well as data from references (for example material properties) and at the end the simulations were done. The essential achievements of the work are (a) downsizing factor (DSF) was defined first time in this article (nobody before), (b) because of possibility of exceeding thermal load in piston (as an example engine part) the changes of DSF has to be restricted to almost 0.95 giving changes of 0.85 for base cylinder diameter and 0.90 ratio of base volume for stroke, (c) the main goal of downsizing to reduce CO₂ emission was results of all tests but it show only 10% benefit, and (d) it is possible to optimise the downsizing technology. So, the next research work will be focused on changes of super- and turbocharging as well as lean mixture combustion for better optimisation of downsizing.