Electric fan conversion..has anyone done one?

[Rversteeg]

No expert in english language, but I guess the shroud prevent air from braking out sideways from the fan, thus impriving the efficiency.
When stationary, the backing plate prevents hot air drawn in by the fan into the engine compartment from recirculating back through the radiator or worse, through the fan again. The rubber flaps act as a sort of non-return valves.

[Laird Scooby]

Pretty much it in a nutshell Rob.

Also when the fan is stationary, the shroud creates a bit of venturi effect around the actual fan area, increasing the speed of the air flowing through it from forward movement of the car.

Again this helps to get a good volume of air through, even without the fan running.

[tofufi]

Originally Posted by monkeh

That fan looks familiar...
You still not fitted it yet?

Oh yes, several years ago. Been working fine ever since, thanks

That was just an image I grabbed from eBay

[TonyS9]

Originally Posted by Laird Scooby

Pretty much it in a nutshell Rob.

Also when the fan is stationary, the shroud creates a bit of venturi effect around the actual fan area, increasing the speed of the air flowing through it from forward movement of the car.

Again this helps to get a good volume of air through, even without the fan running.

The shroud is only for stationary low speed effect to ensure air comes through the radiator rather than from beside it. Its is actually a disadvantage at vehicle speeds above the fan air movement speed, and blocks air flow. Removing the shroud was the biggest improvment I got in my overheating 360 turbo on summer track days. Although it has no speed relief valves as apparent in the pics.
The air may well speed though the fan when the vehicle is moving but that doesn't help anyone. It will be overall slower through the rad because of the shroud. Its is rad air speed that is important. I think the shroud also increase air resistance of the car.

Mostly in this country you can get away without a shroud for non-AC cars.-

[230ina245]

I put an electric fan/shroud (same as picture) on my 240 when I changed the radiator to the shorter 7/940 one. It fitted without any (or not a lot - was a while back) modification. Used the Volvo relay & connected a bmw two temp thermostat switch into an inline connector (also shown earlier) in the top hose. The fan only comes on if left idling for long periods - don't think I've ever heard the high speed except when testing.
Apart from anything else you will be amazed at how much room is created when the old v/fan shroud is removed (at least on the 240). Also, if you need to work on the front of the engine, you don't need to take the fan & shroud off before you begin.
Tim