The high temperatures and pressures produced in the combustion space of an IC engine stimulate
the nitrogen content in the air and also in the grades used (such as heavy fuel oil) to react with oxygen in
the combustion air. In this reaction mechanism, the formation of nitrogen oxides proportionally increases
with the temperature rise. This behavior unfortunately combats the efforts of improving on
engine efficiency because conversion of energy at the highest possible temperature level is to be aimed
for to reach the optimal efficiencies of combustion processes.