Investigations into the Composition of End Gases from Otto Cycle Engines

Techniques are described for determining the chemical nature of the end gas in a normally fired CFR Otto cycle engine. Apparatus for obtaining and chromatographically analyzing representative end-gas samples is described, and its utility illustrated using isooctane as a fuel. Twenty-seven carbon containing slow combustion products were identified before flame arrival; these consist principally of olefins, ring ethers, carbonyls, CO, and CO₂. Product formation is shown to increase with increasing pressure and temperature stress and to be inhibited by octane number appreciating additives. Distinct product formation trends from the slow combustion of isooctane were observed.