2.1.1. Engine

Tests were carried out in a test-bench with a Nissan YD22 four-stroke, turbocharged, four-cylinder diesel engine. The engine bore and stroke are, respectively, 86 mm and 130 mm, and the compression ratio is 16.7:1. The exhaust system (Figure 1) is equipped with a diesel oxidation catalyst (DOC) and a muffler.

**Figure 1.** View of the engine test bench including (**a**) the exhaust system pipe and (**b**) the diesel oxidation catalyst (DOC).
