In this video you will see a unique project of a young Czech engineer – MAREK FOLTIS, a motorcycle powered by a radial two-star two-stroke engine.- BISTELLA 500.The whole project have started 2,5 years ago.The main goal was to create my own engine design, something that had never been used before in any vehicle.
And most importantly I wanted engine design, for such, there are no engineering templates. (for example for inline 4 you can find numerous “stencils of formulas” and you just put your numbers in formulas on page 1 then you put the result from page 1 into the formula on page 2 etc and 40 pages of calculation later you have your engine designed and you don’t have to know anything about physics or material science.
So I chose a supercharged two-stroke radial engine design, which had never been used in mass production before. So I had to make my own formulas.Then I set a goal to make this project on edge of mechanical complexity. (but without self-purpose nonsense gadgets)”One step further in complexity and I would need magic not science to make this engine work.”So one of the goals was as many cylinders as possible
Radial design is the most space-effective.Two rows of cylinders reduce engine diameter.One crankshaft with master rods -> engine diameter and height reduced (but the blower is needed to maintain scavenging cycle).Rows overlap slightly + onesided slave rod connection -> height replacement created space for blower assembly between crankcase and frame.
Using 5 tiny roots blowers is more space effective and allowed me to use high blower rpm (up to 40 000 rpm) so blowers can be small enough to fit in the engine and still are capable to charge the engine. (1,6 charge to cylinders displacement ratio).Then I compared the dimensions of 8,10,12 cylinder designs and I choose a maximum number of cylinders that still fit in the frame without cutting Jawas’ frame. So I went for 10 cylinders. Now clearance of the engine/frame is about 1mm, so it is really close fit.via//read more: bistella