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This study proposes a method to calculate the limit of piston ring conformability to deformed bore based on measured gas leakage flow rate through ring-bore gap and calculated gap area using a test device that allows the creation of arbitrary bore deformation. As a result, it was clarified that predicted conformability can be matched with measured value by modifying a constant value in the conformability equation for a single order bore deformation proposed by Dunaevsky and Tomanik et al. Furthermore, it has been confirmed experimentally that the conformability limit index ∑U for the complex bore deformation proposed by Tomanik is valid. Using ∑U, area of gap between piston ring and deformed bore under engine operating condition was calculated to derive the relationship between blow-by gas flow rate.

This paper represents the adaptation of turbo charger to single cylinder 450cc SI engine which is used for the student formula competition. The experiment and 1D engine simulation called as GT-Power were performed to confirm the effect of valve profile, compression ratio and air fuel ratio on the engine performance under the naturally aspirated condition. The maximum valve lift of the intake valves increased 27% and that of the exhaust valves increased 15% as compared with the low profile cam. The compression ratio was increased from 12.3 to 13.5 by changing the piston top land length in order to improve the thermal efficiency. It was confirmed that the torque peak was moved from 6000 rpm to 8000 rpm by changing the valve profile. Furthermore, turbo charger was adapted to the engine as changing the capacity of the turbocharger, the maximum boost pressure and the air fuel ratio.