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A 40MFLOPs DSP(Digital Signal Processing) based data acquisition and engine control system with 2-microprocessors (one for DSP, the other for host computer) has been developed for the rapid acquisition of analog data from an engine with ECU. With the use of a DSP system, it has been demonstrated that high speed data acquisition by 8 channels (0.8MHz/CH) as well as real time display and real time processing of various thermodynamic & knocking analyses are successfully performed. The engine operating conditions are to be changed through a serial communication interface, and performance of an engine can be analyzed as a function of time or crank angle. As a result, the correlations between engine performance and various engine operating conditions can be obtained with high speed and ease.

The effects of swirl on early flame development and late combustion characteristic were investigated using a high-speed single-shot visualized SI engine. LDV measurements were performed to obtain a better understanding of the flow field in this combustion chamber. Spark plugs were located at half-radius (R/2) and center of bore. High-speed Schlieren photographs at 20,000, frames/sec were taken to visualize the detailed formation and development of the flame kernel with cylinder pressure measurements. This study showed that high swirl favorably affected combustion-related performances in terms of the maximum cylinder pressure and flame growth rate regardless of spark position. However, at R/2 ignition the low swirl showed desirable effects at low engine speed, and degraded performance as engine speed increased than without swirl. The effects of spark plug shapes and rotations on combustion performances at R/2 ignition and swirl were found.