to shroud or not to shroud? thats my question!

[kikkegek]

I bought one of these babys for my Burb:

a 16" reversible electric fan




Now I would really like to mount it straight onto the radiator. But I wonder:
- do I need a shroud?
- or can I just mount is straight on it?

I would really prefer straight on it, since the big shroud I currently hanve takes up a lot of space in the engine bay.

this is what my engine bay looks like now!




lemmeknow what you guys think! OK?

[Dalaigh]

No you don't need the shroud. Infact it would actually impeed the effectiveness of the electric fans. A buddy of mine just did this on his 89 K5 and he said the truck has quite abit more grunt.

[BHBurban]

The shroud helps direct air from the outside through extremities of the radiator core when the truck is moving, and the fan pulls it through. Removing it will cause the electric fan only to effectivley cool the fins and tubes within the diameter of the fan itself.

[kikkegek]

okay thanks guys.

thats
+1 for NO
and
+1 for YES

[Dalaigh]

Because the fans are moved to right on the rad, I'm assuming your mounting them as a puller and not pusher fans, it is no-longer in an optimum position for the shroud to be effective, if you put the e-fan in the same spot as the clutch fan then the shroud would serve a purpose, but mounting the fan to the rad, the shroud will only cause turbulence and lower the fans force against the front of the engine.

[Psycho71]

I shrouded my electric fans on my '71. Have a 16" and a 10" on an aluminum radiator. Driving on the hwy it would run a little warm. I cut some relief holes in the shroud to let the air flow freely and it helped the hwy temps. Still runs good and cool at low speeds too.

Before the alum. radiator, I just had the 16" zip tied to the 3 core brass and copper rad. itself, and it wouldn't cool for squat in 100+ temps at low speed/idling in traffic. Did fine on the hwy though.

Also, if you mount it straight to the radiator itself, make sure you have some good padding between the feet on the fan and the rad. core. Road vibration can, and will, eventually rub a hole in the core with the cheesy little pads you get with the fans. That's exactly why I ended up going with a new radiator and built a shroud for it.

[Zoomad75]

I've got a completely different solution. Get rid of the flex fan junk. Go back to a stock 5 or 7 bladed clutch fan. They work. It was designed for it to run inside the shroud you already have. The clutch fan in my K5 has ALWAYS kept the engine running cool. That's even in 105 degree heat creeping along in traffic. There was a lot of engineering thought put behind the design and use of clutch fans from GM when these trucks were new. Yeah, some of the ideas (like side saddle tanks) were not the best, but the fans work. It's one of the few things that hasn't changed as clutch fans are still coming on new GM trucks to this day.

It might be harder to get a correct clutch and fan in Europe, but it might be worth looking for.

[Dalaigh]

Originally Posted by Zoomad75

I've got a completely different solution. Get rid of the flex fan junk. Go back to a stock 5 or 7 bladed clutch fan. They work. It was designed for it to run inside the shroud you already have. The clutch fan in my K5 has ALWAYS kept the engine running cool. That's even in 105 degree heat creeping along in traffic. There was a lot of engineering thought put behind the design and use of clutch fans from GM when these trucks were new. Yeah, some of the ideas (like side saddle tanks) were not the best, but the fans work. It's one of the few things that hasn't changed as clutch fans are still coming on new GM trucks to this day.

It might be harder to get a correct clutch and fan in Europe, but it might be worth looking for.

They may work, but they rob the engine of power having to spin that fan. And the OP isn't putting a flex fan on, he's putting an electric fan on, which is leaps and bound better then the antiquated clutch fan. The stock fan moves what maybe 600-700 cfm, the electric fan on my V8 S10 pushes 2150cfm and I never need to have the fan on when moving, only when idling in traffic does it turn on. E-fans are the first thing any one should do if they want to get some more power and increase the efficiency of their truck.

[Zoomad75]

Originally Posted by Dalaigh

They may work, but they rob the engine of power having to spin that fan. And the OP isn't putting a flex fan on, he's putting an electric fan on, which is leaps and bound better then the antiquated clutch fan. The stock fan moves what maybe 600-700 cfm, the electric fan on my V8 S10 pushes 2150cfm and I never need to have the fan on when moving, only when idling in traffic does it turn on. E-fans are the first thing any one should do if they want to get some more power and increase the efficiency of their truck.

I fully realize he was wanting to put a electric fan on. I offered a different solution to his cooling problem by ditching the existing flex fan he already had on his truck. E-fans do have their place. But its funny to me to call clutch fans antiquated if the OE's, GM included are still using them on trucks. Including the Duramax Diesel HD's. Keep in mind with a correct working clutch, the fan is only pulling when the temp is hot enough for it to lock the clutch in. Yes it robs power, but it robs less power than that flex fan that is engaged 100% of the time. On a stock engine, much less one that looks like it's running on Propane I can't say that he's going to feel that he's gained a huge amount of power from mechanical fan to electric.

[tobiahr]

to answer the question originally asked it is always a good idea to shroud the radiator fan as it pulls air from (or pushes air through depending on which side is shrouded) the entire radiator instead of just where the fan is directly attached. if you look at the side of the electric fan you have pictured you will see its designed with a small shround that is supposed to be attached directly to the radiator. we have all either seen or heard horror stories of the damage this can cause but it is the way these fans were designed to be used. i have also seen people fabricate fan shrouds out of aluminium that take up much less real estate under the hood and can be just as effective at cooling with the electric fan as the oem clutch fan. see http://67-72chevytrucks.com/vboard/s...d.php?t=216128 for an example on this forum ( or http://67-72chevytrucks.com/vboard/s...=447246&page=4 ) you can also mount them in the existing fan shroud but that would not obtain the results you are wanting.

[mooseknuckles]

I agree^^^

[kikkegek]

Originally Posted by tobiahr

to answer the question originally asked it is always a good idea to shroud the radiator fan as it pulls air from (or pushes air through depending on which side is shrouded) the entire radiator instead of just where the fan is directly attached. if you look at the side of the electric fan you have pictured you will see its designed with a small shround that is supposed to be attached directly to the radiator. we have all either seen or heard horror stories of the damage this can cause but it is the way these fans were designed to be used. i have also seen people fabricate fan shrouds out of aluminium that take up much less real estate under the hood and can be just as effective at cooling with the electric fan as the oem clutch fan. see http://67-72chevytrucks.com/vboard/s...d.php?t=216128 for an example on this forum ( or http://67-72chevytrucks.com/vboard/s...=447246&page=4 ) you can also mount them in the existing fan shroud but that would not obtain the results you are wanting.

thanks man!
those links are very helpfull!

when the fan is in! couple of weeks from now. I'll post some pics!

[BigBlocksRule]

^ and if that little electric motor goes out, you're hot with no way to get home more than a mile at a time. That little fan may move a lot of air, but it's only directly in front of the blades. A properly setup clutch fan with the correct shroud pulls air through the entire radiator.
I prefer a serpentine setup with an extra belt

Has your buddy with "quite a bit more grunt" done any tests or is this butt-dyno only? They're unreliable and affected a great deal by how much money was just spent on the vehicle.

Once up to speed, the clutch fan pulls nearly zero from the engine. The water pump actually pulls a good bit more...

[Dalaigh]

If you buy a cheap efan, yeah it can fail. My old daily driver was a 89 cavalier they came with efans from factory and when the body finally gave out and it went to the scrap yard, the fans still worked and never gave me a problem through the 230000kms I put on it, and with all those cars and trucks out there that have efans from factory no-a-days, efans can't be that unrelieable. For all the arguments that efans will let you down, I've seen flex fans and clutch fans go to. Clutch fans are up to the job, but if you want something that can do the same job and more, well gaining some power and quieting the under the hood noise, go with an efan.



As for my buddy, he had his truck dynoed three years ago when the engine was rebuilt (with clutch fan) and it was 230hp at the wheels. After the efans at first it was the seat of the paints dyno, but he has since had it dynoed and with the efans K&N filter royal purple fluids (engine trans T/C and gears) and new 2.5 exhaust with magnaflow cats, he netted a 22hp gain. Now obviously that didn'tall come from the efan, but he did say he noticed the most improvement after doing the efan.

[kikkegek]

thanks guys!

@ Psycho71: got any pics for me of your setup?

So what I learned from you guys so far, is that I should not mount the fan directly to the rad, because that might damage the rad. thats a good advise. On te other hand, you want to get the fan as close to the rad as possible, because otherwise it will just suck air from the front of the rad and not through the rad.

I have drawn this picture to make my point.


so, please help me, by putting up some pics with details about mounting....that would help me a lot!

[nerphin]

the shroud makes sure air is pulled through the entire rad.

with no shroud the fan can only pull through the surface area equal to the size of the fan.