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Radiator Flow Promoter

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Old 06-29-2004, 05:01 PM
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Garth S
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Default Radiator Flow Promoter

- or a water tube, as Porsche call it (928 106 142 00) is installed in the upper right rad inlet of every car I've seen from MY '86.5. It is basically a tube with a notch cut out to direct flow in the right end tank through a '5 o'clock' centered opening. I presume the function to be one of equalizing flow through (most) all of the core's tubes.
One could guess this is a $50 Dealer part: I took a pattern from one, and in ~10 min made one from a piece of scrap aluminium. Cute as that may be, is there any functional gain to install these 'promoters' in the earlier cars? - or is this a 'great theory' idea that has insignifigant function?
I am contemplating such deep issues nearing the end of the 3rd week awaiting parts - and as you can see, this is scraping the bottom of the barrel.
This flow promoter will go in the '80s rad - unless there is some sage advice to the contrary. The photo is of the template, scrap stock, and a tube hand formed around a 1.25 " dowel.
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Old 06-29-2004, 05:13 PM
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Garth S
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...And sitting in the rad looks like this (when half way in). The width of the piece is 4" before rolled, and the tube is 3.5" long - should one care to try.
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Old 06-29-2004, 05:20 PM
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Jim bailey - 928 International
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Deflector is now over $70 at the dealer IF still available . Looks like a nice improvement , I see no down side .
Old 06-29-2004, 06:00 PM
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PorKen
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Garth S,

Can you make a printable template for the masses?
Old 06-29-2004, 06:32 PM
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Chris
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Well you learn something every day, never seen that part !

Chris
Old 06-29-2004, 07:34 PM
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Garth S
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Originally posted by PorKen
Garth S,

Can you make a printable template for the masses?
Were I not so computer iliterate, absolutely: If someone can advise how, please PM: Otherwise, the dimensions are a rectangle of 4.125"x 3.25". Two rectangles of 0.5"x1.5" are nipped from each 3.25" side as per the pic.
The sheet is formed having the 4.25" becoming the circumference.
The outer edge has two small tabs (or 1/8" cuts would do) to create 'grab' points to keep the thing located at a 5 o'clock center. ( the S4s have a moulded ridge inside the hose nipple).
Old 06-29-2004, 08:18 PM
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jpitman2
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Does anybody know exactly what the function of this thing is please? Is it supposed to improve water flow into the end tank, or ?? A template would be easy to make by flattening it out and scanning it , or scanning a paper copy of it....or faxing a copy to somebody with a scanner....I assume the second pic is the top right corner of the rad?
jp 83 Euro S AT 48k
Old 06-29-2004, 09:07 PM
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Garth S
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Originally posted by jpitman2
Does anybody know exactly what the function of this thing is please? Is it supposed to improve water flow into the end tank, or ?? A template would be easy to make by flattening it out and scanning it , or scanning a paper copy of it....or faxing a copy to somebody with a scanner....I assume the second pic is the top right corner of the rad?
jp 83 Euro S AT 48k
The template used is in the first photo, laid over a piece of sheet Al - the appropriate dimensions are in the second post. The rad is standing on edge in the second shot, so the 'device' would have the notch at a 5 o'clock position when viewed from the back (hose connection) when 'right-side-up'. - sorry for any confusion.
edit: The idea , it seems, is to equalize flow through all the rad core tubes.
The tube is installed when pushed in flush with the nipple - so the hose is never in contact ( only 1/2 way inserted in the photo): a notch or barb cut in the metal will keep the diffuser located.

Last edited by Garth S; 06-30-2004 at 08:41 AM.
Old 06-30-2004, 12:07 AM
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jpitman2
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oK, ENOUGH INFORMATION AVAILABLE. Is it fitted as shown in the rad pic, or further into the side tank? From the pic, it looks like the end would be out near the bend in the hose, and the edges may not do the inside of the hose any good? I guess I am wondering if the wider gap in the device near the tank entry tube is a coincidence of the pic set up, or intended location in operation. must ask my local wrench if he has seen them.
jp 83 Euro S AT 48k
Old 07-04-2004, 08:44 PM
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jpitman2
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garth, I went and checked out a couple of radiators - one tube was a dark material, the other almost off white, felt like plastic. End flush with inlet pipe. Felt like the cut away inside was ~ 90 degrees facing down and right, as in

O--
|cut out here
I make it 1 1/2" (38mm) OD, 1 3/8" ID (35mm), so I will see if I can find some thin wall 1 1/2" tubing that will take the heat, and have it ready for next top hose off job.
Thanks for pointing this feature out.
jp 83 Euro S AT 48k, without one so far.
Old 07-04-2004, 10:40 PM
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Doug Hillary
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Hi,
I noticed this "modification" in the 928 WS Manuals a long time ago when commencing to systematically monitor the engine temperatures on my S4

Coolant will always flow via the shortest possible route in some cases missing to coolant's heat loss potential of the whole radiator.
This type of "directional" device was used a lot many years ago and especially so in heavy diesels as power increased. This was to extract every ounce of cooling potential with an existing layout without increasing radiator size, air flow, complexity or weight. The next stage was to flow the coolant through twice (two passes) via directional gates. Cummins Diesel used this system for some years during the 80's and early 90's.
Directional devices usually work very well as much cooling potential can be wasted. This is probably only at the extremes in the 928 which has an excellent if complex cooling system.

But, as the 928's radiator is a "heat sink" it also has the potential to delay the coolant's flow into the engine via the thermostat in cold weather by using more of the radiator's surface area first.

Regards



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