(coming from seeing my washer/dryer setup in the house)

Of course, not everyone's dryer at home is like this....

On the outside of my old house, the dryer vent had a flapper-style pressure-controlled venting system. It was very simple: some rectangular pieces hung on rods (long ways was parallel to the ground) and the pressure from the dryer venting would allow them to open enough to let air/debris out, but they would shut when the dryer was off. Simple enough idea, right?

Well, I was thinking something like this might work for an e-fan radiator shroud. The biggest problem with them is the fact that because they're so shallow, the best area of cooling is right around where the fan is, and even that area becomes an issue when moving because the fan isn't turning anymore; it's just creating resistance.

My idea is to apply that to the area around the shroud outside of the fan area. When stopped (ie: fan running) the pressure from the fan would keep the vents closed and would allow them to open freely when the car was moving. Or, if you don't think that you'd create enough pressure from incoming air while moving, have a mechanical/electromagnetic setup to open/close the "blinds." Seems like this would be ideal for air movement at higher speeds....

Oh, and I think this would work great for the e-fans that are mounted in front of the radiator, where you have all the factors of heat, etc, working against you, trying to pull in air from the outside, unless you make it a pull fan instead of push.

Ok...I've got my helmet on, I'm ready for the bashing. :-)

 

I don't think that blocking the radiator off around the fan at low speed and stops will help cooling... it will only insulate the radiator and restrict airflow while moving. I could be wrong though...

*Edit... Wait, I may have misunderstood, you mean make a chute around the fan leading to the engine and have the vents open inward? in that case, I can see how that might help at low speed/stops. Not sure the effect it would have at higher speeds though. not sure you would need the vents either...

 

fan running (low speed/stopped) = vents closed so that the fan can push as much air from one side to the other (not just moving air around on both sides)
fan stopped (car at speed) = vents open to allow the airflow coming in to move as unrestricted as possible

 

try it ...intresting idea i mean if it doesnt work just go back to way it was before ...hey i may try it ...

 

I was thinking of something similar except I was going to use a thin piece of rubber that would be sucked in and cover large holes when the fan is on and blow open with your moving.

 

Early VW's (Rabbits and later) had a system sort of like what you are describing. They just used rubber flaps that would be sucked closed by the fan at low speeds and blown open at highway speeds. The shroud fills most of the area behind the radiator and the flaps are on about 1/3 of the shroud.

Great idea, sorry someone beat you to it! I've been working on an idea myself, I'm going to call it the "wheel"

 

You're talking about having the sides of something like this (the flat area next to the fan) open up when pushed on from the rad side.

While this is not the worst idea, it does not have the potential to be nearly as much better than something shaped like the stock shroud as you may think.

It's harder for air to flow through (BS figures here) 2 sq ft of radiator than it is for it to flow through a 1.5 sq ft hole. If you were to just take up the area covered by the fins on the radiator itself you may find that it is less than the hole it's going through.

The big issue is making sure that all of the air that passes through that radiator can make it out that hole easily.

I can't imagine it being any easier for the air to open that door than it is for the air to move over a few inches over the course of a foot.

Other benefits of ducting the air in a funnel like the stock fan are that the fan can work much better than with your doors closed due to the inherent nature of flow of the pic I showed.

You could put doors on the angled sides of the funnel that only open about 20*, but you're looking at such negligible gains if any in the cooling system that it is far from worth it.

I imagine you would end up losing more airflow through the rad in air being sucked into your shroud through your doors even when they're closed.

This is all I can think of that's wrong with this idea at the moment. Let me know if you need more.

 

I don't think this is true. The more open the low pressure side is (engine bay) the easier it would be for the air on the high pressure side (behind front bumper) to flow from point A to point B.

depending on how this "escape door" was designed, it would actually be easier then try to get the air over to the hole. The air is not being directed really toward the e-fan cutout, its hitting the flat panel and spreading out which in its self is causing resistance.

This is why you use something flexible enough to seal. Not metal to metal. Either way, if there was negitive pressure in the shroud, and this "escape door" was closed with small leaks, where do you think the air would come from easier? Through the rad.

Just all I can think of

 

I wasn't saying it wouldn't be any gains at all. I suppose I was just saying that I hope he doesn't think anyone's going to sell one.

The thing is... if you don't have anything pushing the door shut, it's not going to shut. Maybe it usually shuts, but what if you're facing up on a hill?

So... you've gotta have back pressure created by the flap/door/widget.

The biggest issue of all is that you need to have more of a funnel design than what I posted to get the most air to the fan at idle. I don't know how many times you've had a car overheat... but unless a coolant hose blows or you've been sitting at redline all day with a non race prepped motor... you're typically going to overheat in traffic or stopped.

I just think that once you have an efficient shroud adding flappers will make no noticeable difference.

Essentially what I'm saying is that at 40mph you might be flowing 4000cfm through the rad, and the flapper might get you to 4100cfm. Once again these are total BS numbers, but the point I was trying to make two paragraphs up was that it doesn't take near either of those numbers to keep the car cool at 40mph.


Edit: I re-read your post, and I think you are confused on what I was arguing to an extent. I wasn't saying that what I showed a picture of will EVER flow anywhere NEAR as much as the same thing with a flap system. I was only showing that pic to explain to others in the thread what he was talking about.

Re-edit: It seems that you want a lot to debate, and I'm all for it. That in mind... do you think any benefits outweigh the inherent risk of adding complication to a cooling system? What if a flap lets go? Sure it'd be no worse than if you e-fan goes out, but they'll both overheat you. Now you've got 3 things attached to your radiator that if they fail will cost you money instead of just one, and for what?

 

Something like this?

http://www.pwr-performance.com/atv.htm#2

 

Are those "air reeds" just pieces of plastic that flap up when the car is moving?

 

Well you would have the rubber (in my idea) mounted in a way that would force it up agaist the rad. Plus the radiator is tilted forward so that would also hold it to the surface. Remember its just an idea.

Right, but what is easier to move? Forcing air another direction because the air can't push through the aluminum or forcing s thin, about 1/16" thick piece of rubber open?

The funnel would help more when the car is in motion and would also help with the e-fan.

Your right. I would like to see someone build a shroud as efficient as the one that mazda designed.

It doesn't depend on speed. It depends on the amount of HP your engine is creating at such times. If you are cruising around at light throttle say at 40mph, your engine temps should be around 185-190. You floor it, the temps will climb because of the heat generated by the extra HP your engine is creating.

I can watch my GReddy Engine temp gauge rise and fall as the demand for HP increases and decreases.

Understand. BTW, don't take my post as argumentative cause its not, just sharing my side thats all.

Well when I build something, I build in such a way where it won't come apart. I'm always under the hood of my car anyways so I would always check just to make sure. Either way if you build it right, you don't have to worry about it.

 

I'm honestly saying that the constriction is less restriction IMO. Forget entirely about the shroud that I posted. Please... ignore it. I am not talking about flat shrouds at all, assuming that if you are looking for an efficient shroud you will go with a tapered design.

IMO worrying about putting flaps on a flat shroud like that is like worrying about your exhaust tip in regards to performance when your collector is a piece of trash.

This is why I said it is only an issue how much air you flow at speed if you're way up in the revs. I didn't mean way up in the revs but not under load, I mean WOT. If you're running your car at WOT so hard that you need a better fan shroud, then you probably need the stock one. Nothing flows like that beast. Nothing.

I can watch my S4 engine temp gauge fluxuate as I mash all over my car too.

Nope, it's a debate. So far (as i know) noone's gotten upset yet, so it's a good one. I am a little tipsy at the moment though, so I hope I'm not being more rude than I think.

I guess I'm just a little paranoid. I've seen everything fail. I'm convinced a rock can fail, and I don't mean breaking under pressure. I'm pretty sure that given enough time a rock will fail to be a rock.

Nothing is fail safe.

 

Understandable.

The stock fan setup will win hands down every time unless your racing all the time. Even then I can't see it loosing if you have a good radiator.

The thing is, the higher the revs, the more HP the engine is creating, not matter if you are at WOT or not. Infact I realize I was not very clear on the driving conditions.

At 40mph right? In your first sentence about going 40mph, it seemed as though you meant that no matter what condition, at 40mph there would be enough air to cool the engine without any help of the fan.

Thats good.

Agreed. I know everything can fail at one point of another. Just if you build it right, you should have to worry about it for many years to come.

 

It's called a "cowl flap" or "exit flap".

That is pretty much true. A running fan starts to become a restriction at about 30-40mph.

 

WOW, where was I last night. I guess my fingers were typing but my head was some where else. Ofcourse thats true. Smack my head up against the wall. 40mph is fast enough I must have been thinking of going slower then that. To hate my self more, I even drove around months ago without my e-fan hooked up for about 30minutes at various speeds, various throttle inputs and watched my temp gauge rise but never to the point where I needed the fan.

 

yea, so i guess it has been done on some other products

kontakt, yea, i don't doubt the superiority of the stock clutch fan/shroud, but i was hoping i could use this for an *e-fan* shroud that i could locate it in front of the rad before the oil cooler (a/c cooler removed in my case).

edit: thx for the replies everyone, i may give this a shot once i figure out the best way to go about construction

 

What no forum bucks for me for telling you you were on to something?

 

Yeah, what I was trying to say is that if you're doing 40mph at high load high rpm... you're not going to be doing 40mph for very long at all. You'll be at 80+ in no time.

However, if you were to just sit in 2nd gear at 40mph without accelerating, you would technically see higher temps going up a hill than down. I don't know how measurable this would actually be though. The only way to be at full load at 40mph at a fixed RPM would involve being in a wind tunnel set to 40mph pushing the wheels against a huge brake. I do feel, however, that in this condition you would generally be alright.

I generally see temp changes like this. If I'm doing 45, cruising some back road, and I get to an extremely desolate spot and let 'er rip it'll go from 1/4 gauge to 1/3 gauge... maybe. Of course when my coolant seals were going it'd sit at 1/3 gauge, and beating on it would go a little past 1/2, but as soon as you let off of it at speed it cooled right back down. Yeah yeah... not good for it to beat on it when it's blown, but OTOH I was told that my 90k irons looked like 10k irons.

I certainly don't see a temp change at 45mph when I go up a hill vs down a hill (load, as well as RPM determines HP output). When your engine is free-revving without any load on it, it is not actually making horsepower. In order for it to push on the drivetrain the drivetrain has to push back (equal and opposite reaction). If the motor is freewheeling, then it only takes the amount of horsepower to accelerate the rotating assembly as you climb the revs.

This doesn't actually have a whole lot to do with the conversation as a whole though. I could probably tie it in, but I'm getting lazy.

OP you will have a PM shortly.

 

Short version would be HP and heat generated is a function of throttle opening.

If you need 2nd gear and full throttle to climb a hill at 3000rpm the engine will run hot without an electric fan.

 

+1 bucks