*2.1. Test Engine, Fuels, Operating Schedule*

One of the tested engine was a compression ignition engine made by FCE Powertrains. The main parameters of this engine are presented in Table 1. The arrangement of the cylinders is in line with the Double Overhead Camshaft. The engine is fueled with diesel fuel and meets the EURO 5 standard. The engine has Common Rail direct injection

system. The engine also has anelectronically controlled Exhaust Gas Recirculation valve, the operation of which is aimed at reducing the emission of harmful compounds in the exhaust gas. The EGR valve directs some of the exhaust gas from the exhaust system to the engine's intake system, thereby lowering the temperature in the combustion chamber and slowing down the combustion process. This allows the emission of nitrogen oxides to be reduced. The engine is also equipped with an oxidation catalytic converter and Diesel Particulate Filter.

**Table 1.** Engine's parameters.


The second tested engine was a spark ignition four-stroke engine with a capacity of 0.05 dm<sup>3</sup> used in motor scooter. The engine is fueled with unleaded gasoline 95. Diesel engines were tested on an engine dynamometer test cell equipped with a brake AMX-210/100. The maximum power of the brake is 100 kW, maximum torque is 240 Nm, and the rotation speed is 10,000 rpm. The tests were based on the engine load characteristics, which consist of assessing the change in basic engine parameters, depending on its load at constant crankshaft rotation speed. The tests were made for three rotation speeds: 1800, 2100, and 2400 rpm. For every rotation speed, at least seven engine loads were tested, from 15 Nm to 135 Nm, in steps of 20 Nm. The exception is the test for 2100 rpm, when the regeneration of DPF has become apparent, and, for this rotation speed, the number of tested loads is 8 points.

In the case of the petrol engine, the research was conducted differently. Due to the fact that the engine was mounted on a scooter, it was necessary to use a chassis dynamometer for two-wheelers. Due to the above fact, it was only possible to carry out tests for the qualitative determination of whether the engine was under load or not.
