INCIDENTAL to the cooperative fuel-research work of the author, which has been described in another paper, was a study of the effects of other operating factors. The results of these observations are presented in this paper.
The effect of unequal fuel-distribution through the inlet manifold was studied by running acceleration tests on two cylinders at a time. Other series of acceleration tests showed the effect of jacket-water temperature with a cold inlet-manifold and of spark advance. Data are presented also from laboratory acceleration-tests simulating low-gear conditions, and showing that deceleration tests recorded by means of a spark accelerometer are useful in measuring friction under temperature conditions that are more nearly like the running conditions than are friction tests made by motoring the engine by means of a dynamometer.