The puller fan "may"restrict air flow but it's cool air flow that has already passed through the heat exchanger before it hits a possible restriction.... Hence it has already cooled the coolant...
The pusher fan restricts air flow before it enters the heat exchanger, just by it's physical size impeding said air flow, and again this restriction is before it has had a chance to enter the heat exchanger so theres less air flow to cool the coolant.
No comparison....
re. shroud, a properly installed shroud has the effect of creating a low pressure area within the space between the radiator and the fan/output. Air being air will rush to fill a low air pressure condition. The air entering the low pressure area will travel through every orifice contained within the radiator to fill the low pressure space. A shroud increases the overall heat exchanging efficiency more so than a similarly equipped vehicle without one.
Thermal dynamics at it's most basic.....
Puller be better than pusher.... LOL...
Dave
