International Scientific Journals
of Scientific Technical Union of Mechanical Engineering "Industry 4.0"

Overcharging is one of the most effective methods for increasing the power output and improving the energy efficiency of spark-ignition internal combustion engines. It has a significant influence on the processes of mixture formation, combustion, and heat release, which necessitates a detailed experimental investigation of the engine working process. This paper presents an experimental study on the influence of supercharging on the indicator diagram and the heat release coefficient of a VW-1600 GTI spark-ignition engine equipped with a K-Jetronic mechanical fuel injection system. The appropriate operating modes, defined by engine speed and load, were selected to ensure reliable measurement and comparison of the investigated parameters under naturally aspirated and supercharged operating conditions.

The paper presents numerical analysis of in-cylinder pressure and temperature change for naturally aspirated gasoline engine and two of its upgrades – upgrade with turbocharger only and upgrade with turbocharger along with air cooler. Numerical analysis was performed with 0D (zero-dimensional) numerical model. In-cylinder temperatures, for each engine rotational speed, are the highest for engine upgraded only with the turbocharger. The highest observed in-cylinder temperature of turbocharged engine was obtained at 5000 rpm and amounts 2542.4 °C. In-cylinder pressures are the highest for engine upgraded with turbocharger and air cooler for all rotational speeds except the highest one. The highest observed in-cylinder pressure of a turbocharged engine with air cooler was obtained at 5000 rpm and amounts 129.7 bars. Presented analysis showed that the selected air cooler can be improved at highest engine rotational speed.

The paper presents numerical analysis of air after turbocharger cooling process and its influences on the gasoline engine operating parameters. Analysis was performed with numerical 0D (zero-dimensional) simulation model by using two sets of simulations – for gasoline turbocharged engine without air cooler and for the same engine with air cooler included. Between engine rotational speeds of 1000 rpm and 5000 rpm, air cooling process increases analyzed engine developed power and engine torque up to 20.67%, increases cylinder maximum pressure up to 17.03%, increases engine volumetric efficiency up to 23.65% and reduces brake specific fuel consumption up to 1.32% when compared with the same engine without air cooler. At the highest engine rotational speeds (between 5000 rpm and 6000 rpm) it was observed that selected air cooler does not offer the required and expected performance, so air cooling process in this engine operating area can and should be improved.

Numerical investigation of naturally aspirated gasoline engine main operating parameters and engine upgrade with a turbocharger is presented in this paper. Analysis is performed by using numerical 0D (zero-dimensional) simulation model. Turbocharging process with a selected turbocharger increases engine maximum torque for 62.58 % and also increases maximum engine effective power for 58.82 %. One of the main reasons of turbocharging process usage is reduction of engine brake specific fuel consumption. The highest decrease in brake specific fuel consumption for a turbocharged engine, in comparison with naturally aspirated one, is obtained at 4000 rpm and amounts 8.83 g/kWh (from 239.01 g/kWh for naturally aspirated engine to 230.18 g/kWh for a turbocharged engine). Turbocharging process brings several useful benefits to the analyzed gasoline engine, which is also a valid conclusion for internal combustion engines in general.