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Crankcase Supercharging Question

  1. Sep 27, 2011 #1
    There is a four stroke Model Airplane Engine made by Yamada (YS) that uses a rotory valve in the back of the crankcase to compress a fuel/air mixture for two rotations in the valve cover, before it is admitted by the intake valve. The fuel contains oil which lubricates the bottom end. Excluding pumping losses, this would make about 14lbs of boost. YS claims 30% increase to power/weight figures compared to nat. aspirated motors.

    My question is whether this has been done with larger boxer engines, like a BMW. It would seem a huge waste of energy to blow and suck the total displacement of the engine overboard with every revolution. Even with pumping losses, it seems a waste of energy. With standard oiling, one could just pump air and use EFI to add fuel at the valve.

    Am I missing something or has this been done and proven to be not useful.

  2. jcsd
  3. Sep 28, 2011 #2
    If the crankcase is sealed there wouldn't be much loss compressing and expanding the air quickly. Pumping it through a valve like your engine would be a different story though.
  4. Sep 28, 2011 #3
    so, with pumping losses, heating, and other issues, is there a net gain with the boost provided?
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