On Fri, 23 Dec 2011 16:43:17 +0000 (UTC), Steve Firth
wrote:

Cobblers. The Atkinson cycle does not improve efficiency at low rpm. It is
designed to maximise efficiency at a given, constant rpm which for the
Pious is IIRC around 3k rpm.

Quite. Just like genset engines - cam timing and breathing optimised
for a given rev range.