which of the former has the most efficient power delivery. all things equal : bore, stroke, breathing of heads, pushrods to pushrods, ohc to ohc, etc... the only difference to be tolerated is of course there will be more moving parts on the V/H6 engines due to copies of moving parts.

just for clarification

I6 = inline six/straight six
V6 = vee six(of what ever angle)
H6 = flat six/boxer six/horizontally opposed six

Steven Folchi