upgrading to slim fans....Fan Shroud OR no Fan Shroud????

[mrod900]

Running a performance header on my non turbo VR6 Corrado. Never got around to wrapping it with heat wrap and just this past week my radiator started to leak. My radiator fan has been making some noise lately also so, I figure now is good time to upgrade with a dual 12" spal fan setup.

Should I make a fan shroud for the mounting or should I use those plastic push rods that come with slim fans that punch directly through the radiator?

[RedYellowWhite]

I was told that its better to modify and use the oe shroud with slimline fans. And I quote: "That way you eliminate "dead spots" where air will not be pulled thru the rad at idle and where the fan would contact the rad causing the "dead spots" at higher speeds"

[vwflygti]

use those plastic push rods that come with slim fans that punch directly through the radiator

Just used them two nights ago...
Makes for a nice tight and clean install:

[dogger]

I was told that its better to modify and use the oe shroud with slimline fans. And I quote: "That way you eliminate "dead spots" where air will not be pulled thru the rad at idle and where the fan would contact the rad causing the "dead spots" at higher speeds"

Shrouded is suppose to be much better from what I found out from asking around. I'm swapping to dual slim lines on my car and talked to several engine and race car fabricators. They all said you will get better efficiency across the entire radiator with a shroud. If you are looking to save time I'm sure its not a big deal. I'm planning to build a composite shroud that will fit either single or dual slim line 12" Spal fans for my car. A mold will be made so we can offer them from SFT.

[vwflygti]

Shrouded is suppose to be much better from what I found out from asking around. I'm swapping to dual slim lines on my car and talked to several engine and race car fabricators. They all said you will get better efficiency across the entire radiator with a shroud. If you are looking to save time I'm sure its not a big deal. I'm planning to build a composite shroud that will fit either single or dual slim line 12" Spal fans for my car. A mold will be made so we can offer them from SFT.

Nice, of course anytime you can make/have room for a shroud that will cover 100% of the radiator it will work better than two round fans covering 80% of the radiator. But if two slimline fans don't get you what you need, an aftermarket radiator should be in the works... These babies pull some air! I've been running two of these on my s4 with great success with a shroud. expecting great results without a shroud also. Will deff update soon as this thing should be running next week...



This may sound funny but with the shroud and 3 electric fans I think at times the s4 is too efficient The fans tend to run such a short time to satisfy thermostate.

[yosa12]

Shrouded is suppose to be much better from what I found out from asking around. I'm swapping to dual slim lines on my car and talked to several engine and race car fabricators. They all said you will get better efficiency across the entire radiator with a shroud. If you are looking to save time I'm sure its not a big deal. I'm planning to build a composite shroud that will fit either single or dual slim line 12" Spal fans for my car. A mold will be made so we can offer them from SFT.

Do you have a timeframe for offering the fan shroud? Also will it be available for a VR6?

[dogger]

The plan is the make a VR version. My goal is to have it ready by the end of April. They will come in fiberglass, carbon fiber, and carbon/Kevlar.

[dannyace]

The plan is the make a VR version. My goal is to have it ready by the end of April. They will come in fiberglass, carbon fiber, and carbon/Kevlar.

Any idea on pricing yet? And where are folks buying their 12" slimlines?

[RedYellowWhite]

...And where are folks buying their 12" slimlines?

ebay?

[dannyace]

Did a little more searching, a few folks have had ordered through http://www.the-fan-man.com

[vwflygti]

Here is where i got mine. They are local to me though...
http://www.jscspeed.com/catalog/Univ...ting_Kits.html

[hallkbrd]

There is no need for a fan shroud with fans that cover most of the radiator, unless you drive up hill at slow speeds and need near 100% efficiency.

You are much better off ducting the radiator in front so air must go though it - and not around it.

A fan shroud is only a positive thing when you are not or barely moving. The rest of the time it just reduces the effectiveness of the radiator. And if your not moving, your engine isn't making much heat to get rid of.

[hallkbrd]

These babies pull some air!

Hopefully they are pushers and not pullers on that side of the radiator.

[dogger]

There is no need for a fan shroud with fans that cover most of the radiator, unless you drive up hill at slow speeds and need near 100% efficiency.

You are much better off ducting the radiator in front so air must go though it - and not around it.

A fan shroud is only a positive thing when you are not or barely moving. The rest of the time it just reduces the effectiveness of the radiator. And if your not moving, your engine isn't making much heat to get rid of.

When your not moving your engine isn't making much heat to get rid of? What is the engine turned off in this situation?

If the engine is running and the car is not moving the engine certainly will generate plenty of heat. Even if its moving slow in traffic its generating heat. That is the whole point of having fans on the radiator is for those situations. To push or pull air through the radiator to cool the engine.

And a fan shroud will certainly make the fans more effective especially since your not going to get fans that cover a majority of the radiator. There are going to be large parts of the radiator where cool air is not being pulled across it. When the car is at speed the airflow will still be fine with a shroud or every car company in the world wouldn't be using them and spend the time/money to make them work efficiently.

[hallkbrd]

When your not moving your engine isn't making much heat to get rid of?

Exactly. Don't think so? Do this test.

From cold, start your engine and just let it idle. See how long it takes to get up to working temperature. Then the next day, start your engine and drive and note how long it takes to get up to working temperature.

Mine takes about 10 minutes at idle, or about 1.5 minutes in 45 MPH driving. No contest - an engine under load uses more fuel and thus makes more heat.

Even if its moving slow in traffic its generating heat. That is the whole point of having fans on the radiator is for those situations. To push or pull air through the radiator to cool the engine.

Yes, it is generating some heat - but not near as much as when under load. And yes, with no fan at slow or now speed you have no heat extraction - except a minimal amount from radiation - so yes, you need a fan for that reason. OEM's and most interested in cost and quiet operation, not efficiency. A slower shrouded fan at slow speed sounds better than a faster non-shrouded one.

And a fan shroud will certainly make the fans more effective especially since your not going to get fans that cover a majority of the radiator.

Again, that depends how much of the area the fans actually cover. Typically if that is more than about 60% and the high-speed fans are well sealed to the radiator face, you don't need a shroud from my experience. And when moving forcing all air to go up against the shroud and through the fan is definitely less efficient that it just flowing straight though in the non-fan areas. Adding ducting to force air though the radiator is the key for cooling while moving. When air meets the radiator, if it can go around it instead of through it - it will. Path of least resistance.


Seriously though - if cooling is that iffy without a shroud and those two new high-speed fans, what is needed is a better (or possibly just new) radiator. He could also consider using Evans coolant instead of water/glycol and gain another 100 degrees of buffer before boiling coolant. That especially helps in the heat of summer where the temperature delta from the air coming off the road is much closer to the boiling point of water/glycol than other times of the year.

Here is what I am running - a single high-speed fan on an all-aluminum afco scirocco radiator with Evans. No problems any time of the year, or on the track.

[turtledub]

The plan is the make a VR version. My goal is to have it ready by the end of April. They will come in fiberglass, carbon fiber, and carbon/Kevlar.

Insert "shut up and take my money" pic.

[TheBurninator]

Insert "shut up and take my money" pic.

[dogger]

Exactly. Don't think so? Do this test.

From cold, start your engine and just let it idle. See how long it takes to get up to working temperature. Then the next day, start your engine and drive and note how long it takes to get up to working temperature.

Mine takes about 10 minutes at idle, or about 1.5 minutes in 45 MPH driving. No contest - an engine under load uses more fuel and thus makes more heat.




Yes, it is generating some heat - but not near as much as when under load. And yes, with no fan at slow or now speed you have no heat extraction - except a minimal amount from radiation - so yes, you need a fan for that reason. OEM's and most interested in cost and quiet operation, not efficiency. A slower shrouded fan at slow speed sounds better than a faster non-shrouded one.




Again, that depends how much of the area the fans actually cover. Typically if that is more than about 60% and the high-speed fans are well sealed to the radiator face, you don't need a shroud from my experience. And when moving forcing all air to go up against the shroud and through the fan is definitely less efficient that it just flowing straight though in the non-fan areas. Adding ducting to force air though the radiator is the key for cooling while moving. When air meets the radiator, if it can go around it instead of through it - it will. Path of least resistance.


Seriously though - if cooling is that iffy without a shroud and those two new high-speed fans, what is needed is a better (or possibly just new) radiator. He could also consider using Evans coolant instead of water/glycol and gain another 100 degrees of buffer before boiling coolant. That especially helps in the heat of summer where the temperature delta from the air coming off the road is much closer to the boiling point of water/glycol than other times of the year.

Here is what I am running - a single high-speed fan on an all-aluminum afco scirocco radiator with Evans. No problems any time of the year, or on the track.

I wasn't comparing the difference between the heat generated under load versus when a car isn't moving. What I am saying is that a car that isn't moving has an engine that generates plenty of heat. Your scenario of a cold engine idling makes a senseless and unrealistic point about the effectiveness of cooling fans and a shroud. The reality is that cars are driven and not always are they moving at a high enough speed to move enough air through the radiator to cool the car. Take your same cold start scenario and let that car sit there running for 30 minutes on a hot day and tell me that engine isn't generating much heat. Why not unplug the cooling fans and than tell me how little heat that engine generates. Your coolant temps will go through the roof without a effective cooling fan(s).

Track cars are totally different. Your not sitting in stop and go traffic when racing or dealing with the same variety of driving conditions that road cars deal with.

So a slower shrouded fan is more effective than a unshrouded high speed fan? Production road cars are built to have efficient and yes cost effective cooling systems. I don't understand your point. If cost was so important than why wouldn't they save the money and not use shrouds? They use them because they are more efficient. I'm sure if they could get away without using them the accountants would love that.

[cata]

All I know is that us VR guys run hot. I have a completely refreshed cooling system and if I leave my car to idle from a cold start, the fans will start coming on after 15 mins tops. The shrouds increase cooling efficiency at low speeds. Stressin about engine temps in the middle of traffic on a hot summer day isn't my idea of enjoying ownership.

Count me in for a fancy shroud too

[vwflygti]

Hopefully they are pushers and not pullers on that side of the radiator.

No, they are pullers. That is the back side of the radiator. Radiator is not in the car at this point.


Here is the rad in with a third fan, a pusher, in front of it...


Car has low, high, and accessory fans/speeds.

[mrod900]

just placed order on two 12" Spal fans. I tried going to Ebay but was having a hard time finding two identical fans from the same buyer so I went to the Spal website. I'll be starting work this tueday and wednesday and post some pictures.

http://www.spalusa.com/store/main.as...&item=30100467

[hallkbrd]

Look, I'm not going to make a fight of this - that is silly. An engine makes the same amount of heat on a hot day as it does on a cold day, it's just easier to get rid of the heat when the temperature delta is larger.

BTW - Spal fans are great, just expensive and with no replaceable parts.

If you want a shroud and it makes you comfortable - get one. But keep this in mind, here is the custom-made radiator I used for several years with two fans on it in 100 degree summer weather, and traffic. I did make a shroud for it - since it needed all the air draw possible when not moving in the summer heat. Now this is for a 1.8T and not a VR6, but their heat output is roughly the same, so it is a good comparison of what you can get by with. Note, I do run Evans though - so boiling point for me is at around 375, not that I pegged the 250 needle with this setup (until a rock punched a tiny hole in it), causing me to change to the larger cheaper afco unit.