I found this while researching what makes up most of the losses in an engine. While this may or may not be the highest it certainly is up there. I'd never have thought of this and i wonder if it will ever make it a little more mainstream?
If we are going to use IC engines for the forseeable future then this needs to make headway and quickly.
http://www.rotatingliner.com/RLE-Art...nal-022404.pdf
RLE | Rotating Liner Engine
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