I am preparing to put the radiator back in today and reconnect everything.

I don't really like that clunky shroud around the big (mechanical) fan. What if I install the fan without the shroud?

Did anybody do this and running their cars without the shroud?

I assume if one tightens the fan properly, the chance are very slim that it can become unglued. Also, one can also conduct periodic checking to make sure everything is tightened properly.

Or is it a bad idea?

 

Of course you can! Is it a good idea? Not in my view!!


The shroud's function is to allow the mechanical fan to pull air through all of the core, not just the middle.


An unshrouded fan, either electric or mechanical is cools the core less than a shrouded one.


The factory engineers are not dumb. We DIYers learned that decades ago.


Caveat. Don't risk an engine failure. Do I have real life experience there, no need to ask, it is clear....


Carl

 

The fan whether mechanical or electric become redundant after about 30 mph as the air is flowing through the rad and a/c condenser to keep things in check so the shroud is very important in stop and go traffic.

Randy

 

In the case of the mechanical fan the shroud is important, as the fan blades are quite a distance from the rad core and without the shroud it would not suck through the core effectively. Apparently (I have been told by someone who understands the dynamics of fanned flows) an unshrouded blade does not need a shroud if it can be mounted right against the core, but the XJS mechanical fan cannot be, as the engine moves independently of the rad. Most if not all electrical fans have a guard ring round the blades that is also used to fix the fan in place. Therefore providing the electric fan is mounted close to the rad (as in 1/2 an inch away max) a shroud is not needed as the guard ring is an effective preventer of airfllow being short circuited instead if being sucked through the core. I mount mine 1/4 inch from the core. If you are worried about chafing, a foam pad between the guard ring and the rad core is a good plan too.
Greg

 

That is what I have been told as well. E-fans should be closed around the edges... Otherwise it won't work properly... Kind of like a room fan isn't as efficient as a modern closed fan (like those Dyson ones).

 

I saw a technical paper years ago from the SPE ( Society of Petroleum Engineers) about cooler performance in gas processing plants and it was looking at the shroud-fan interface. These coolers use large (up to about 15 foot diameter) fans to cool gas after it has been compressed.

The conclusion was that shroud is critical, as is the gap between the shroud and the blades. If the shroud isn't there, the air spills out the ends of the blades, and doesn't create any draw, so it can't pull any air through the radiator. In the testing, the paper said that the gap needs to be as small as possible for efficiency, and with a gap of 3/4" (on a 15 foot fan) the amount of air it could pull across the cooler core was reduced by 70%.

That's why on some electric fans you'll see the blades and shroud moulded together, so the "shroud" moves with the blades to make the blade tip gap zero, and makes the fan as efficient as possible.

So the answer is fit the shroud, and make sure the blades are actually covered by the shroud.

 

The centrifugal force of the blade rotating causes a lot of turbulent air on the blade tip this reduces efficiency and causes noise. So a blade ring will improve air flow and reduce noise.

If you look at the new aircraft with the winglets these do the same thing as the shroud around the blades.

You do not need the whole radiator shrouded only a ring around the blade tips.