D.Hearne, I think WORTH's idea was to make peak pressure at 90* ATDC, to get maximum work out of the energy in the cylinder. This most likely would occur near the end of the fuel burn cycle as nearly all the fuel is burning at once but in a conventional motor by the time it is all ablaze, the CR has dropped a lot so you don't get peak pressure there, it occurs earlier. If you could use the moving cumbustion chamber to hold more pressure longer, you would get more work out of it. Man could you imagine seeing the individual combustion chambers on a V8 going up and down. HAHAHA it'd be comical, they shake enough as they are without external bits going as well.