To find a suitable engine for snowmobiles — the task is far from simple. Series motors in many aspects (in particular, power density) does not satisfy the Amateur designers. This makes certain enthusiasts to elect quite difficult, but the right way is to create motors own designs, using components and parts of serial.
The editorial Board has provided the pages of the magazine designers and enthusiasts, discussing the principles of design of engines, their technologies, So, of particular interest to the readers of the article that generated the F. Kiseleva (“M-K” No. 6, 1978), which describes the technology of manufacturing of reciprocating engine — motor having a number of advantages compared to other engine circuits. Today’s article A. Kozhakhmetov from the city of Troitsk, Chelyabinsk region — on improving the “oppozit”.
Trinity at city station of young technicians, we have built several snowmobiles and karts. The main engine used tractor of puskach PD-10. What we just did with these motors: and crossed them, and mated, but the desired results to achieve and failed. Great weight, size, relatively low power density, and forced variations and unimportant life. Tried to increase power by improving the scavenging, but it didn’t help.
The fact is that on most two-stroke engines the inlet of combustible mixture to the crankcase is controlled by the piston. The window it opens, not reaching 60-65° before top dead center (TDC), and closes it later the same 60-65° after its passage. Thus, the intake phase is symmetrical relative to TDC, and there’s nothing you can do, since the relative position of the edges of the window and the piston with its both up and down are one and the same.
For improvement of cylinder filling mixture inlet it is desirable to begin 130-140° before TDC and ends after 40-50°.