The dependence of the turbulent flame speed and the flame development angle on air-fuel ratio, engine rotational speed, ignition timing and compression ratio has been verified. An isooctane-fueled research engine has been utilized in the experiments. The turbulent flame speed and the flame development angle have been determined with the aid of a spark ignition engine cycle simulation model. The results from this work confirm existing theories on the influence of engine design and operating parameters on the turbulent flame speed and on the flame development angle, but suggest the way they relate is to be better established. The effects of knock and incomplete combustion have also been examined.