RADIOACTIVE TRACERS have been used to study the fuel distribution among individual cylinders in two modern V-8 engines. Individual fuel components (both hydrocarbons and fuel additives) were “tagged” with radioactive hydrogen (tritium) or carbon-14. These “tagged” components were blended into a commercial-type fuel, and their distribution to engine cylinders was determined by measurements of exhaust-gas radioactivity. The quantity of fuel distributed to the cylinders was measured by an exhaust-gas analyzer of the catalytic-cell type.
The results reported include the effect of various fuel factors, operating factors, and engine design factors on the distribution of both whole fuel and its components. A study of octane placement within the boiling range of the fuel revealed differences among fuels when rated under accelerating conditions (with “manifold lag”) and when rated at constant-speed conditions with poor fuel distribution.
Also discussed briefly are the improvements in engine power, economy, octane requirement, and fuel ratings which resulted from improved fuel and tel distribution obtained with a modified carburetor.