THE investigations described here by Mr. Porter were initiated to evaluate the relative importance of pertinent diesel-engine variables, the relative effect of fuel properties, and to compare laboratory and service results on cold-starting performance. Tests disclosed:
Required cranking time is decreased with increased cranking speed, increase in surrounding temperature, and decrease in altitude.
The starting performance of undoped fuels is predicted by the delay cetane number. Increase of cetane number results in greater ease of starting. With doped fuels, however, the delay cetane number may or may not predict service starting performance.
It was indicated by tests on one make of engine that laboratory results may be used to predict service starting performance.
Various substances are effective as starting dopes, but the report indicates that an auxiliary applicator should be used, and warns that the effect of such materials on maintenance should be determined first.
The author outlines in detail the test equipment used, the test procedure, and the results.
Among the additives used were chlorine, hydrogen sulfide, amyl nitrate, ethyl disulfide, and chloropicrin. These ranged in amounts from 20 to 35 ml at ambient temperatures of 20 F, for starting in 5 sec.