Pusher fan: Top, middle or bottom of radiator?

[parkwood]

you are right, if you're running a shroud that covers the whole radiator. i see a lot of guys who run steel fans (flex or hard) without a shroud and if they don't get the fan as high as they can the motor will have a hard time cooling. if the hot water comes in at the top and it doesn't get any air pulled thru the radiator until just before it goes back into the block you will over heat... etc: stop lights on a hot day, running around the fair ground at a show,, how many times have you seen cars boil over doing that?
I've had very good luck cooling components, they have the shroud that covers the radiator and the little flaps on the bottom. move a lot of air and it comes thru the whole radiator..