Shroud Depth

I was doing the math on the shroud (not in the same fashion as the Shroud Math thread) and made my first test shroud, but then I started thinking about how the depth of the shroud--distance between shroud and fan--can affect temps. I based my shroud around the distance between the fan and heater core, which was 3 cm in this case.

Would it be better to increase or decrease that distance? The closer the fan is the faster the air can move through heater core, but at a farther distance it can envelope more fin area of the heater core. Is there a consensus over how far the fan should be from the heater core, or do I have to make 3 shrouds and test them myself? I really don't want to go through all the trouble of making 3, so I'm hoping someone here has an answer to this.

Not really sure that putting a fan closer helps move air faster, but if you make a sealed shroud that will not allow air to go anywhere, but through the heatecore, then about a inch should work fine. The idea is that it cuts out dead spots and allows air to come through entire heatercore instead of just part.

I agree with an inch .I think I read somwhere the further the better I have mine at 2 inches and it appears to work well..I have no comparisions though to tell if closer or farther is better..DO a search on shrouds.

Mine is at 2 inches also. Important part is to get a good seal out of it so that air is being sucked or pushed through the Rad instead of sneaking around it.

1.5-2in is good

fubulg6000 said:

... Would it be better to increase or decrease that distance? The closer the fan is the faster the air can move through heater core, but at a farther distance it can envelope more fin area of the heater core. ...

Click to expand...

Well, no. So long as the air is forced through the radiator (i.e. no leaks), and assuming that the same surface area is covered by the shroud, the air velocity will, on average, be the same regardless of shroud depth. Use whatever depth is convenient, though it's helpful to use an inch or more if possible to minimize fan noise due to turbulance.

Yes at less than 1" fan blades are too close to the rad surface (turbulence..). Also consider the "engine dead spot" that decreases "active" radiator surface area.
IIRC BillA made some experiments on that precisely, and (IIRC again) after a minimum depth of like 1 or 1.5" further depth is not useful.