[Duffman]

I also agree that you are barking up the wrong tree. The drag that is costing energy is created at the piston top. There have been some good ideas bantered like cylinder deactivation, some not mentioned but discussed before like reducing RPM through gearing, introducing inert material to create additional pressure (EGR or water) or running lean.

You can get a similar effect to what you seek by advancing your intake lobe on the cam but this is only good if your CR is not already relatively high (as you are moving the opposite of Atkinson effect). I think a smaller intake plenum would also have a similar effect.