I am puzzled by why there is no seal there? Seems that is killing the fans effectiveness by allow air to come in from the sides instead all the air being drawn directly through the rad. Anyone tried using some type of seal to correct in what my opinion is a design flaw? Ideally you would have a large plastice shoud that the fan connects to then the shroud would have a seal that runs around the perimeter of the rad so air is drawn through the entire cooling area. Even the stock twin fans look to have no seal.

I might try some type of seal just around the fan housing so at least it is drawing all the through the rad even if it is just a small circle.

yeah the dual fans dont have any type of sealing and seem to work great for cooling still. i would think sealing around the fans total would block some of the air flow kind of.

i think what matters with a nice eletric fan the the cfm's and the closeness of them to the radiator.

I think the idea was to minimize restriction when the fans are not running (ie when the car is at speed). That probably yielded a cooler running system that didn't need the fans as often... Also, because the fans are so close to the radiator as compared to a mechanical fan (which need shrouds) there isn't much room for the air to sneak in behind the fan blades from the engine compartment. Assuming your condensor area is sealed properly everything should work great, especially with the factory dual fans...

Just as a guess, I'd say the reason for lack of shrouding, as like a conventional mech. fan, is the electric fans have the venturi ring around the outer edge to help aid the pull of air through the radiator instead of just moving what air is around the blades.

If the fan is within 2 inches of the rad a shroud isnt necessary. The fan is capable of pullingall the air it needs thru the radiaator.

Someone explain the fact the higher end after market electric fans are now coming standard with a shroud that has a rubber seal that is against the radiator? Our B&M electric fan in the truck is a dual fan set-up with shroud and the blades are appr. 1" away from the radiator fins. These have some serious cfm and when I let go of the brakes at the starting line they've been known to move the truck backwards Seriously though, anytime you can direct the air flow it's going to lead to more effective cooling since the air has a set pass it must follow and the shroud with electric set-up makes sure all air moved by the fans is drawn across the radiator period. The motor in the truck is only 550hp but it can idle all day or drive around with nary a temp problem. I'll be sure to post sometime this summer when I get mine installed in the car.

But which will be more effective at speed, a disengaged electric fan with a shroud or a disengaged electric fan with no shroud? I think that was the balance that was desired-- sufficient cooling at low speeds and optimal cooling at higher speeds...

Even with a shroud it is still forcing all incoming to blow across the radiator, the important peice of the puzzle. Just like the duct work under the nose of the few GTA's I seen that gives the air a direct inadvertant pass to go nowhere but into the front of the radiator. I guess in my primal thinking the radiator is the only means at cooling an engine. Think of the some of the race cars-know it;s not exactly a daily driven car-they have radiators mounted behind the cabs with the only form of air flow is what's being sucked or pushed through the fans all of which have a shroud in one crude form or another, even if it's just a plastic shroud that surrounds the fans blades. IMO having a shroud is the only way to force air weather it's slow moving or not to blow across the radiator which sole purpose in life is to keep the coolant temp low. Without having Lockhed Martin doing a wind tunnel test I can only imagine the buffeting in our engine bays at any speed so the shroud is offering a dedicated path to move air over the fins regardless of speed. ?

Yes, this is true..

Well, what about your first statement?? The air will go through the radiator with a shroud or without when the vehicle is moving..

As I said-- With a shroud, the air has to PUSH the fan and exert force to move the fan in order to continue PAST the fan.. Therefore, a shrouded system isn't as effective when the vehicle is at speed. I said nothing about a shrouded system being ineffective at low speeds (or even ineffective at high speeds, I'm sure it probably still cools well).. I simply stated that when the vehicle is moving, the most efficient design is the least restrictive design as far as airflow across the radiator is concerned; this means a shroudless system.. Since electric fans can be placed so close to the radiator as to minimize the amount of recirculated air vs fresh cooling air, their efficiency is high enough to not need a shroud.. Therefore, since the cooling at low speeds is quite sufficient without shrouds, they chose not to sacrifice higher speed cooling by putting them there anyway... I hope I have made sense, I think we are discussing different aspects of the same general concept here..

EDIT: just so we are clear, I am just talking about Electric fans... Things change when we're talking about mechanical fans...

LOL, I think your right. I'm not an engineer by any means, just trying to make an educated guess on what's what. I do know my factory dual electric fan set-up and factory aluminum radiator had troubles at times in parades/cruises keeping my extremely low hp motor cool during the summer and long periods of sustained idle. The fans are full on at 160* as is the electric water pump and neither shut off till 140* The only way to cool 'er back down was to make a hwy pass and then jump back into the parade/cruise. That's what I know from personal experience I know I'd never have a mechanical fan stuck in my you know what ever again either. Even my work truck picked up amazing seat of the pants pull when I removed the clutch fan and installed elctric units-and I left the clutch fan shroud in place over the radiator so the twin electric fans were tucked neatly inside out of sight out of mind. No cooling problems there, with my itty bitty 302cid moving a 3ton truck and pulling a 3ton trailer on race day up and down hills. Again, dont know what this proves if anything at all, just my experiences.

I have a single fan so it only covers maybe 50% of the rad so 50% has free flow at all speeds. Besides how many times have you heard someone complain their car overheats on the e-way as oppossed to overheating in stop and go traffic? Also there should be plenty of space for air to pass between the blades, it can't be much of a restriction at. I'll try a seal around it and see if it makes any diff.

BTW My vette came with a shroud that covered the whole rad and cam past the fan a few inches.

sigh...

fine... I'm tired of repeating myself...