Abstract
Small pressure transducer and signal transmit system were developed, and applied to measure the inter-ring gas pressure in a four stroke SI engine running at a full load condition. Inter-ring gas pressure was measured to tune in the orifice discharge coefficients for the concurrent simulation study. Measurement of cylinder pressure and blowby were also made simultaneously. Discharge coefficient of top ring was observed significantly lower than that of other rings. Simulations were performed under the starved lubrication condition using a commercially available RINGPAK program adjusted with the experimental results to investigate the influence of piston ring assembly design variables on blowby and friction.