The objectives of the Grant required investigations of cyclic variations in a homogeneous-charge engine initially with gas combustion and the air from ranging from near quiescent to the incorporation of swirl and tumble by valve inserts. Later experiments were performed with unleaded gasoline. The measurements included local velocity and cylinder pressure through the four strokes of a single-cylinder engine, under motored and firing conditions and with examination of the flame kernel growth by combinations of photography and flame-ionisation gauges. In all cases, the measurements of in-cylinder characteristics were linked to performance as measured in terms of speed and its variability, load and emissions. The experiments progressed to consider deviations from homogeneous charge and included consideration of stratified charge with local injection of a rich mixture in the vicinity of the spark gap so as to establish a flame kernel which would propagate securely into an overall weak mixture.