For analysis of in-cylinder flow from intake to compression process, a optical engine with a quartz sleeve for high engine speed was developed. This engine was able to be driven up to 10000rpm. We measured and analyzed in-cylinder flow using PIV. According to the result, 2 pairs of vortex were observed under intake valves on intake process. This vortex is a feature flow of engine with high volumetric efficient intake port. We also evaluated in-cylinder flow of 2 valves and 1 valve deactivation. A turbulent intensity of 1 valve deactivation was about 3 times one of 2 valves and it was confirmed to obtain the combustion promotion by turbulence at high engine speed on both of optical and metal engine.
