STD.VW COOLING FANS

Bruce;

Many years ago, I had a Corvair Monza Spyder, Turbo, 150hp.  I always carried extra fan belts. Breaking or throwing one off, was a regular occurrence.   Other than that, the car was a beast, at least for a 19 year old guy!

I didn't have any cooling problems that I recall, but it was 1969-71, awhile ago.

art

Yes, the Europeans are doing it with really good success.  Might look at 1303 Germanlook in google.  They are really doing some trick stuff that I feel we are being left behind.  They do cars for the Autobahn that have to sustain high speeds for a long period and keeping the motor cool is essential.

That looks like a Corvair. I remember you could put the fan belt back on by sticking a large wrench in the belt and have someone turn it over. Presto the belt is back on and you did not turn a bolt. 

There are a lot of aftermarket cooling kits for for the T1 (and T4 engine).  Years ago Jake Raby published a study of their cooling efficiency.  BLF they look kewl but were not effective at evenly cooling all cylinders.  Chrome and carbon fiber look nice but don't cool better.  There are several T4 engines installed in a Speedster with the OEM flat cooling intact (where fan drives off end of crank).

Bad picture above - this is a little better (not my car)

Here's couple Corvair-like horizontal cooling system on T1 engines.

Before we get totally off-track from the original question, (not that all of this hasn't been terrific info and enough to get me to seek out a couple of German air-cooled sites (wish my German was better, but there IS Google Translate), the original question was (I think), could one use a stock, VW cooling fan and mount it horizontally.

The answer to that is no.  The stock VW fan pulls air into the middle, too, but it is a totally different fan design (more of a "squirrel cage" layout) that wouldn't lend itself to a flat application as shown.  

All of those spiffy fans shown above are purpose-made for that application (although it's similar to a 911-style fan, just laying down.

The fan we use looks like this - a whole different puppy:

Has there ever been any engineering done to see if there is a more efficient design for the stock VW fan as installed?  I'm guessing the German Engrs have the best that can be used but it's almost 60 year old technology.

Yeah, fortunately, Bernoulli's Principle hasn't change a whole lot in the past 60 years.  The fans we used to cool computer cabinets looked a lot like the VW fan, just thicker.  It's a remarkably efficient design and there's a lot going on in that design.

Interesting thing about computer cooling - Cabinet cooling designers used to install filters on the input (bottom) side, up until the mid-1980's, when it was determined that (a.) customers never changed them and (b.) they didn't get very dirty, anyway.  After that, the designers simply increased the velocity of the air going up through the cabinet, such that any dust going in just kept on going right out the top and never sticks to the computer logic boards (or anything else, either).

I recall reading Jake Raby's shroud cooling study back in early 2000ish.  I think it was in Ultra VW magazine in 2004-2005.  I was only able to find references to it - not the actual tech study.  From what little I recall from physics indeed reference low/high pressure areas, vanes for directing air to increase flow  IAW Bernoulli principle, metal conductivity - heck, even chrome plating or painting metal parts affects effective heat dissipation.

Here's ref to his study -

http://www.914world.com/bbs2/l...ndex.php?t36778.html

http://www.airspeedparts.com/f...dex.php?topic=3194.0

Study was years ago but I'm sure the Brazilian/Chinese shroud makers didn't read it to add the vanes or OEM VW unseen engineering marvels.  Seems all the DIY "improvements"  of removing the thermostat and flaps or chrome plating stuff was for naught. Remember when "hot" thing was using T3 under cylinder tins for increasing cooling?

Thankyou Gordon, for trying to answer my question more specifically. I was just thinking about how expensive the Porsche fans are and also Bernie Bergmans. I was also thinking about what someone mentioned a while back that these (above) fans force air in and then it has to bend two times in order to flow down through the cyls. and heads. In a  standard VW fan and shroud the air doesn't have to bend at all. This got me thinking about laying down the VW fan horizontal. The air only has to bend once and upon further thought it would be easy  to "bend' the air that occurs front and rear with the use of some deflectors to go right or left.

It just seemed to me that using the VW fan in this method, the air would (like now) be pulled in thru the center and radially delivered  to cool the engine both right ,left and frt to rear but re-directed to right and left.

Also I don't get it on the nomenclature about what is axial flow and radial flow ?

Your comments please....now that you maybe have a better understanding of where I'm going with this...............Bruce

Oh heavens, for what ever cosmic reason,  I ventured over to Bernie Bermann's website last week.  No news in the astro physics department.

There was a fellow sometime back on here, who had worked up a new shroud and I think Carey tested it?  What ever became of the  project. As I  recall, he peaked several people interest with his shroud.

Art

Turns out it was better suited to sustained high speeds than to stop and go traffic, so he marketed it under the name The Shroud of Tourin'.

Wolf:

Jake put up about 25% of the data for about a day or two over on theSamba and STF. It was in the early days of his business when he was working pretty hard to overcome misgivings people had regarding Type 4s, and I think he might have been worried that "the hobby" would not accept the DTM unless he proved it worked. He had spent a LOT of time and money compiling information regarding what worked, what didn't, and why. If I recall, he bought one or two of every single after-market shroud available at the time, and also tested stock VW cooling systems.

However, almost as soon as it went up, it came back down. He was even more concerned about the tendency VW people have for being really "thrifty", and worried aloud that if he put his data up, somebody might benefit from it and undercut him on a cooling system that worked well. Science in research universities works like that, but I think he figured that publishing all of his data would be a great way to give a competitor the benefit of the many hundreds of hours and thousands of dollars he had invested in testing-- and he wasn't feeling all that altruistic about just giving it away. He had cut a deal with the overseas VW mag to publish, and was going to be paid for it, but I don't think it ever got done.

In the end, I bought two of them anyhow. I don't think the DTM was ever a big money maker for him, because the price was pretty high for what it was and the prevailing wisdom held that the stock shroud worked really , really well. Never mind that nobody was using the stock shroud, nobody wanted a (then) $500 chunk of fiberglass.

In the beginning, Jake offered the data to people who would purchase the shroud. I bought the first one in 2005, but never got the data. By the time I bought the second one in 2008, he was offering to provide data for one competing system with a purchase. I bought a second, and never got the data for that one either.

To be fair, they work really well (despite how they look). I monitor all 4 cylinders and the temperature gradation is minimal, and the temps are in line.

Within the last couple of years, Jake sold the DTM rights to LN Engineering, and I think the price is pushing up on $700. That's a lot of jack for a chunk of fiberglass, but as I said-- they work.

Ancient history, and probably boring as all get-out-- but there it is.

About the difference between axial and radial fans.... allow me to opine......

zzzzzzzz

Axial flow versus radial flow:

In the diagrams below, the top diagram shows radial flow (along the radius of the armature of the fan).

The bottom diagram shows Axial flow (Along the drive axis of the armature of the fan)

A stock VW fan is a radial fan.  The so-called 911 fan (Bergman's and others) is an axial fan.

The top one pushes air out at the outside end of the fan circumference, directly into the flow design of the fan shroud to follow a natural path towards the cylinders, then to be pushed over the respective head (left or right), all in a straight line following a curved surface.  There's quite a bit of velocity at the top half of the fan shroud, decreasing in velocity as it approaches the heads (because the fan shroud widens out as it approaches the heads) and dispersing across the cylinder fins.

On a 911-style shroud, the bottom diagram pushes air out of the center of the (vertical) fan, then it has to make a 90 degree turn downward, then separated left and right (there was a divider on the two shrouds I looked at) and then 45 degrees downward toward the heads.  

The Corvair (and the Porsche flat 8 and flat 12 engines on the 917) pulled air downward into a plenum and pressurized it, then out of the plenum left and right sides, flowing over each set of heads taking one less turn.

They sure look neat!

Being an ME with degrees in thermodynamics and heat transfer, I'd love to get into this one, but I will resist the temptation.  Only advice I could offer is: use what works. I'd trust the guys who designed and built the engines first and foremost.  That said, I can see the Corvair-style arrangement as likely being very good, excepting the business about turning the twist (i.e., fan belt) 90 degrees to get it to work.  But the guys at Porsche worked that one out too, so why not.  The pics above for Type 1 flat fans look REALLY COOL.  Bet they work great.  Believe I'd do one of those before I'd do a DTM.  But really, I'll just use my VW dog-house . . . until I can't.

As to how it ought to be done, This one says '61 RS 61L.  Where's the fan belt??

This one seen at Carlisle a while back.  Again, where is the fan belt??

art posted:

Oh heavens, for what ever cosmic reason,  I ventured over to Bernie Bermann's website last week.  No news in the astro physics department.

There was a fellow sometime back on here, who had worked up a new shroud and I think Carey tested it?  What ever became of the  project. As I  recall, he peaked several people interest with his shroud.

Art

The guy with the four cam shroud? What ever happened to that guy?

From an article in Hemmings, a description of the 917 motor - probably how the two motors pictured drive the fan, too? Is the first a 908?

"...With a 120-degree firing order, the engine had more inherent balance than the eight-cylinder 908, though it had the same 85 mm by 66 mm bore and stroke of the 908. When engineers calculated that the ends of the long crankshaft would experience second-order oscillations resulting in significant vibrations, they designed the engine's power takeoff to come from the center of the crank.

 On the bottom of the engine, the center gear drove a propshaft that transferred torque back to the clutch at the transaxle and also powered the multiple oil pumps. From above, the gear powered the four camshafts, two per side that operated a single intake and exhaust valve on each cylinder. The center takeoff gear also powered the top-mounted fiberglass cooling fan via a bevel gear. The fan required as much as 17 hp to run at 90 percent engine speed and could move up to 5,100 cubic feet of air per minute.

 Although the fan provided approximately 80 percent of the cooling necessary for the 917, like all air-cooled engines, its powerplant relied on proper oil cooling to maintain temperature. A thermostatic valve in the dry-sump oiling system (capacity was a voluminous 21 quarts) would open when the lubricant hit 185 degrees to send oil to a large, multi-row oil cooler mounted in the nose of the car..."

Obviously . . .

And we really should call our cars OACs vs. AC, as in oil and air cooled.  Just sayin' . . .

There is a guy on shoptalkforums.com that's designing a centermount fan shroud.  Their test mule: 

The test for the centermount is a 1.6, 7500 RPM sprint engine for HSR, highly balanced, and dry-sumped.

http://shoptalkforums.com/view...hp?f=15&t=146288

I'm sure that I will reveal my ignorance with this question, so don't everyone do a "pile on!"

Could an electric fan be used, are they powerful enough? 

I just found my own answer, I wonder if it works? 

https://youtube.com/watch?v=JuhOK8kezT8

Cole Thompson- posted:

I'm sure that I will reveal my ignorance with this question, so don't everyone do a "pile on!"

Could an electric fan be used, are they powerful enough? 

 

 

No. I don't remember the details, but it has been discussed on here before (and on the Samba, and the Cal Look Lounge, and Shop Talk Forums, and...). I'm sure someone with an explanation (sp?) will chime in shortly. Al