Section A - Cooling System, continued.....

Subject: RE: Aluminum Radiators
Date: Thu, 4 Mar 1999 09:25:49 -0700
From: Bennett Cullen-P21988
To: "'spook01@mindspring.com'"

Subject: Aluminum Radiators (sorta long post)

Hi Ray,
To answer your questions with my personal experiences with an aluminum radiator:
{How well do they work both moving and stationary?} I live in Tempe Arizona and have been driving in ambient 123 degree summer heat. Under those conditions, stationary will tend to creep up on the temp meter pretty quickly. But, not to the point of puking fluid. On a normal 105 degree day it will take 15 minutes of idling to see a temp around 205 on the "calibrated" meter. Under normal running conditions, mine stays at 195 solid. Mine works well enough, that I was able to put an air conditioner condenser core out in front of it, and that sure makes life more enjoyable inside while taking trips (of course the air goes off and the top comes down when we get there for "cruising". On the way back from Big Bear last year, out on the desert it was hot enough (both air temp and radiated road heat) to boil the gas in the fuel line (read attempted vapor lock on cheap gas) before it got to the pump without over heating (air conditioner was on full) the engine. On that day, the meter was reading around 220 (the highest I have ever seen on it).
>Is there a full wrap shroud available with it? The stock Tiger did not have a lower half on the shroud. To make one go to the drug store and get a big sheet of construction cardboard, take a first guess at what it will take, cut and fit. If its too small in an area, use a stapler and put some of it back by overlapping the cardboard. Once you have one that "fits" pull it out and use it as a template to cut some sheet metal from the hardware store. I bought mine at an "ACE" hardware. I attached my final lower half to the original shroud with a single sheetmetal screw (one on each side). The lower shroud tucks under the bottom of the radiator.
>Cost? $480.00 about three years ago.
>How long did it take to get? About three weeks. This totally depends on their work load and the time of the season. They build a LOT of radiators.
>Where did you get it? What is their phone number and location? The radiator is custom built by "Ron Davis Racing Products" on the West side of Phoenix. The address is:
Ron Davis Racing Products
7334 W. 108th Ave
Glendale, AZ 85307
(602)-877-5000
There are a lot of other "considerations" to implement that will help the situation out a bit. They include, closing off the holes on either side of the radiator with clear Plexiglas to prevent recirculating the hot air, a modified six blade "rigid" Ford fan blade (that has references on previous postings) with about 1/3 of the blade surface sticking outside the opening in the shroud. Seal the edges of the shroud contacting the radiator with sticky backed foam rubber to allow for a "low pressure" area to form inside the radiator/shroud compartment. It is this "low pressure" that sucks air through the radiator and is blown out the back by the fan blades. Run no more than a 50/50 distilled water and antifreeze mixture, error on the side of more water if you are not sure. Calibrate your temperature meter so you know where you "actually" are operating. Check your ignition timing so as to minimize excess heat generation. AND AN ABSOLUTE MUST if you use an aluminum radiator, put some zinc or magnesium metal in the system as a sacrificial anode for the electrolysis to eat-up. Several auto parts stores sell chrome plated (outside) thermostat housings that are almost pure zinc. They are cheap, $10 (relative to the radiator) and easy to change out and discard every couple of years. Use a normal pressure radiator cap (for other considerations, i.e. heater core). Use a thermostat, (mine is a 180 degree) with 4 additional 1/8" holed drilled through the area outside the valve. All of these valves require 15 degrees to move from where they are rated (start of opening) to where they are fully open. I have not found even one exception to this observation. Hope this helps,
Cullen Bennett (B9472658) Tempe, Arizona USA

ANOTHER VIEW ABOUT ALUMINUM

Subject: Re: Aluminum vs Copper
Date: 18 March, 2000
From Bob Palmer
To: Richard F. Flynn

Opinions are free but "rigorous data"? That you'll have to pay dearly for. ;-) Actually, I could probably write several paragraphs on thermal conductivity and a comparison of aluminum versus copper and even throw in some data too, the bottom line of which is it doesn't make a nickel's worth of difference in a radiator. Before I say why this is so, I might point out that the purity of a metal has a very big influence on its thermal (and electrical) conductivity. Stainless steel, for example, is a very poor thermal conductor compared to pure iron (or pure nickel). I could explain this in terms of phonons and quantum mechanics, but you can get a feel for this classically by thinking about colliding billiard balls. When the billiard balls are the same size, they transfer momentum most efficiently. If you have a pure metal, all the nuclei (billiard balls) are the same size and it will conduct heat pretty well. If you alloy two very different size nuclei together, it really screws up the momentum exchange and the thermal conductivity goes to hell. The effect at very low temperatures can be several orders of magnitude; in fact, this is a pretty good way to measure purity. For completeness, I should also point out that in a typical metal, approximately half the heat is conducted by the conduction electrons, the same ones that carry electrical current. That's why metals are generally better heat conductors than insulators, although there are some very high thermal conductivity insulators like diamond and beryllium oxide, for example. (I'll resist the temptation to explain this phenomenon. ;-)

The reason the purity discussion is relevant to comparing copper to aluminum is that industrial copper is relatively pure, whereas most aluminum structural parts are highly alloyed for strength, which makes the thermal conductivity of typical aluminum alloys a lot less than copper, radiators included. (BTW, an interesting engineering fact about structural aluminum I learned a while back is its failure limit is zero; i.e., it will fail eventually, no matter how small the applied stress is. Makes you think twice about flying in an old airplane, huh?)

From the previous argument, it would seem that copper is the best material to build a radiator out of. However, the thermal conductivity of the radiator is scarcely a factor in its efficiency. You could even make one out of stainless steel and it would work just about as well as copper or aluminum. The biggest impediment to heat transfer in a radiator is the air/surface interface, and to a lesser extent, the coolant/surface interface. There is scarcely any temperature drop across the thickness of the cooling tubes. Other factors, like weight, are very important though. I had occasion to pick up an empty copper radiator for a Tiger, one of the really good ones which, incidentally, worked extremely well. It weighed a ton! I couldn't believe how heavy it was. I didn't actually weigh it (see, you have to pay extra for real numbers), but it must have easily weighed twice or three times as much as my aluminum radiator. If you don't mind an extra twenty pounds or so on the front of your Tiger, then copper has the practical advantage of being pretty easy to repair compared to aluminum.

I understand by private communication that there is a better aluminum radiator undergoing testing on a Tiger with very impressive results. It is not as thick as the Ron Davis radiator. The source is Fluidyne, who supplies radiators to NASCAR, etc. You can check them out at:
Fluidyne

Right now, a radiator for a Tiger would be special order, but if there is enough interest, maybe one of the clubs like CAT will have them make a limited production run. I'm sure it won't be available for this summer though.

Hope this amuses if not instructs.

Well, TTFN

Bob

At 05:34 PM 3/18/00 +0000, Richard F Flynn wrote:
>I hesitate to ask, but does anyone have and rigorous data on aluminum or copper
>is better at dissipating heat? I have been told by a HVAC type that copper is
>usually the metal of choice for cooling systems in buildings because it is
>more efficient than aluminum, yet people on the list seem to have had improved
>their cooling situations with aluminum radiators.
>
>Any hard data out there?
>
>thanks in advance,
>
>rick

P21988@email.mot.com

Subject: Re: Waterpumps? Date: Mon, 03 May 1999 08:53:54 -0700 From: Steve LaifmanTo: Stig RamCC: tigers@autox.team.net References: 1

Stig Ram wrote:
> I«ve changed (tried to) the waterpump on my Tiger Mk 1.----.After a lot > of this
> and that I found that the Workshop manual > said 5,15 inch (130,82 mm) between the engine mating surface and the > waterpump Hub-pulley. I measured 131 mm on my new pump as well as on > another Tiger pump. But my old ( not reparable) pump has approx. 125 mm! > And is perfectly aligned w. the crankshaft and generator pulleys! So now > to the QUESTION(s): > What engine does I have?
> :-) Stig Ram > Ps. My SnowTiger as well as my Alpine SV is presently hibernating, > awaiting the Spring, Its cold here.
Stig,
I have found data that suggest the venerable Official Workshop Manual is in error in this measurement. It does indeed list 5.15 inches for the MkI, MkIA 260, and 5.43 inches for the MkII 289.
My information says the "correct measurements" should have been 4.875 inches for the MkI/IA, and 5.1 inches for the MkII.
Hope this helps.
Steve
-- Steve Laifman B9472289

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