A NEW research tool, the crank angle-time recorder, is described. This instrument conveniently obtains a permanent record of the time at which various combustion phenomena occur in the engine cycle. Use of the recorder in studies of normal and abnormal combustion (deposit-ignited surface ignition) has provided information of interest to both engine designer and petroleum refiner.
Studies include determinations of those deposit-ignited flame fronts which result in knock, effect of fuel antiknock quality and additives on surface ignition, and resistance of fuels to surface ignition. The records obtained show that considerable variability exists in the time at which normal flame fronts arrive at an ionization gap. Some factors affecting magnitude of this variability are ignition timing, fuel-air ratio, engine throttling, changes in manifolding, and fuel type.