In order to clarify theoretically the advantages of crankcase-supercharging, the proportion of the drive load of crankcase-supercharger to the output of engine and the increase ratio of mean effective pressure were studied through thermodynamic theory, and then suitable inlet systems were also examined. The validity of estimated values were checked with the experimental data.
As a result, it became theoretically clear that a mean effective pressure rise of about 9% to 17% could be obtained by crankcase-supercharging. And it was estimated theoretically that comparing the crankcase pumping load with the output of engine, the former became only about 2.5% of the latter and the suitable inlet plenum volume is about 150 times the displacement volume.
Additionally, estimated values are proved to be adequate for practical use by comparing with experimental results.