Electric fans?

[Boog]

ok, well, just out of curiousity, I have just browsed Summit's catalog and there are over 900 listings in the cooling/heating section covering direct drive fans, fan clutches, blades, controllers, shrouds, sensors and electric fans and all that goes with them. Quite a number of offerings out there.
Back to where I mentioned earlier about some dual fan setups having vents made into them for increased air flow at highway speeds I found numerous ones listed so there is definately something to this. Most of them have a rectangular rubber flap over them that can open up under increased air flow through the radiator and remain closed at stop or slow speeds for more fan draw through the rad. The PermaCool setups do not cover their 12 holes at all.
I am listing the part # for several of these if anyone is interested in what I have found.
BeCool BCI 75007, 95007, 75037, 75044.
Flexalite FLX292, 295, 298, 278.
Permacool PRM19510, 19513,19514,19515, 19516, 19524.
Each one of these have vents made into the shrouds.

Intended as useful info when selecting a fan setup or diagnosing a cooling problem.
The top pic is a Permacool, then second one is a BeCool. Notice what look like black flaps on the BeCool unit.