Diagnosis

As pointed out at the outset, the sole purpose of combustion in a piston engine is the generation of pressure in order to shift the expansion process away from compression and create a work-producing cycle. This transition is manifested by dynamic symptoms: the measured pressure profiler and the concomitant piston motion. Its action is referred to, therefore, as the dynamic stage of combustion. The generation of pressure is motivated by thermochemical transformation of reactants into products taking place in the course of a process referred to as the exothermic stage Changes in the composition and thermodynamic states of the reacting substances (metamorphosis) taking place within this stage are deduced from the measured time profile of pressure — the procedure of pressure diagnostics. Treated thus is an inverse problem: deduction of information on an action from its recorded outcome. Its solution yields, in effect, a measure of the effectiveness of the exothermic process of combustion in a piston engine, akin to the account of an auditor on the operation of a business enterprise from the records of its transactions — a well established methodology in acquiring guidance for its improvement.