On the Effects of Intake Pipe System in a Small Two-Stroke Cycle Gasoline Engine : 1st Report, The Effects of Length of an Intake Pipe

Abstract

To examine the effects of length of an intake pipe and the engine speed on the delivery ratio (or the breathing capacity) in a small two-stroke cycle engine, the authors have measured the amount of air flow and analysed some pressure diagrams for the intake pipe, crank case and cylinder. Some conclusions obtained in such experiments are summarized as follow : a) The delivery ratio (K) at the motoring differs little with that at the firing. b) The maximum delivery ratio occurs on account of the inertia-effect as same as in the case of four-stroke engine and the matching conditions are expressed approximately by the following equation [numerical formula] c) According to the equation, the optimum length of intake pipe (Ls or L) engine speed (N or ω) or timing of inlet port (θs) can be determined, and then the relation between the pipe length and engine speed is easily shown to be given by N·√(Ls)=constant. d) In special cases of long intake pipe or high speed, the pulsation waves in the intake pipe have inffuence on the delivery ratio and such pulsation-effect is governed by the following expression [numerical formula] Thus the pipe length is related to engine speed by the equation N·√(Ls)=constant, so that it may be noted that the pulsation effect differs essentially from the inertia-effect mentioned above.