Originally Posted by swamp2
It is more about displacement and mass of reciprocating and rotating components. I don't know the record holder for V8 on hp/l but the smaller the displacement the higher the revs and the higher the hp (of course assuming all other engineering top notch). Just look as 1 liter superbikes, ~15k rpm and ~180 hp/l.
Superbikes don't weigh much, so they can go with an incredibly short stroke design, which allows for much higher RPMs (16K - 18K redlines) and thus more hp/L, but no torque in the normal drive range.
This engine design would not work in a 3000 lb car - it would never get off the line.