*2.3. Methodology of Measuring Process*

The tested engine was operated at two stabilized engine speeds: 1000 rpm or 1500 rpm and at different engine loading levels (Table 3). The cooling water temperature was maintained between 75 ◦C and 85 ◦C. The lubricating oil temperature was kept between 90 ◦C and 100 ◦C, depending on the operational conditions. The values of engine fuel consumption, exhaust gas temperature and NOX emissions were continuously monitored in three-minute intervals, whereby the measured results were averaged.
