Your "smaller" area of 1953mm2 is equal to a 50mm duct. In what engine is this maybe not enough?I have an air cooled twin engine that shares the same bore and stroke as a more modern liquid cooled engine. The liquid makes very good power. I am essentially taking most characteristics from the liquid and applying them to my anemic air cooled turd. I have ground off the Cooling fins around the exhaust duct and welded up the area for auxiliary exhaust ducts before welding fins back on. Also welded up the floor and the bottom corner radii with aluminum sticks ( thanks for the tip wobbly ) will be doing the 75% nozzle on this and reshaping the duct to oval. The air cooled is a cylinder reed with very little intake area and no good way to add larger reed blocks due to the design limitations and rear studs. I know... I know I could cut the pistons and so on but I would rather have a nice inner transfer radius and a case reed air cooled. I have cut the reed blocks off of the liquid engine and am planning on welding them to the air cooled engine. Even though the bore and stroke is the same, the liquid has a taller case and shorter cylinder than the air cooled counterpart, due to the intake design amongst other reasons I am sure. There is not enough room between the crank bearings on the air cooled engine with the shorter upper case half ( the case splits horizontally ) for the liquid reed blocks to have straight unblocked flow into the crank case. The rectangle area of the aluminum after the pedals on the reed blocks is 2480mm2. If I keep the height the same and reduce the width to the width of the case between the bearings it would be 1953mm2 at the case. My idea was to make the reduction in width with a block of aluminum welded between the reed blocks that I cut from the liquid engine and the air cooled case. I know this would also add to the case volume and or intake length? ( If that makes sense to anyone I will be surprised ) This finally leads me to my question. Is it acceptable to have a smaller intake area after the reed petals at the crankcase, or would it be a better idea to transition the rectangle into a square of the same area? I ask this because I know the inner area of the reed block already is not the same as what is going through the reeds.
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