Do a lengthly search on the web for "Soft head" and you should get several links to this technology.
Try here for starters...........
I think Energy Dynamic's, Inc. (i.e., ENDYN), leads the pack on this??
And just maybe Dr. Gas and McFarlands "sloped/diveted" shaped piston crowns too?? I hope I've remembered this one right, it's been a long time?? Search for Dr. Gas.........