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Old 11-22-2014, 08:59 AM   #4 (permalink)
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Felix Wankel Patented the "Rotary" engine, which is not really a rotary, in 1926, if my memory serves me properly, almost 90 years ago.

The basic flaws are the surface area of the combustion chambers and the problems with sealing the combustion chambers. I had one of the first RX2s and the fuel mileage was atrocious (13.5 MPG). The engine basically blew up at 13k miles and I got a replacement free, even though the car was salvaged.

The surface area and shape of the cumbustion chamber with flat surfaces on the sides means serious heat transfer issues and differential rates of expansion of those surfaces make sealing almost insurmountable, even after 90 years.

To keep the tip seals from melting you have to lubricate the tip seals with oil losses similar to a two stroke engine. Not quite that bad but bad enough that, in my opinion, it's dead end technology.

Many major manufacturers including Mercedes tried to overcome those design "defects" and not one of them has succeeded.

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