Strontium Dog
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| posted on 8/3/10 at 11:27 PM |
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Alloy Radiators
I read a thread about alloy vs copper rads here and came across this on another site I am a member of.
Cheers to "Sunny" on the GT4DC for this info,
WHY ALUMINUM RADIATORS ?
Tubes are the primary source of cooling. A radiators cooling capacity is governed by a number of factors. Most important are the tubes, the primary
source of cooling. Heat dissipates from the coolant (water and antifreeze) through the tube wall (primary), then through the fins (secondary). Air
passing through the fins carries away heat, thereby allowing tubes and fins to absorb more heat from the coolant. In serpentine fin (VT) construction,
the flat side of the oval tube is in direct contact with the fin, providing secondary cooling. The rounded ends of the tube are not in direct contact
with the fin and therefore do not provide secondary cooling. On the other hand, the rounded ends of the tube provide strength to the tube keeping
internal pressure from pushing the tube into a round shape (ballooning).
In the beginning, there was the copper brass radiator. Copper brass construction seemed the obvious choice for the first radiators because of superior
heat conductivity, ease of forming and ease of repair. The earliest radiators used round tubes. Manufacturers moved to 1/2' oval tubes in the
late 1920's which worked well with the low-powered engines of the day.
In the late 1940's, Ford began using 5/8" tubes. In 1958, GM followed suit using 314" tube with a wall thickness of .005. This wall
thickness worked fine on 1/2" tubes but proved too weak for the wider tube thus GM ran into problems with ballooning. GM ultimately recognized
the cooling advantages of the wider tube and forged ahead with a new tube with walls .007 thick. GM also tried one other approach. They built a
radiator that used 3/8" tubes. By increasing the number of tubes in the radiator, GM was able to compensate for this smaller tube size. The
smaller tube had virtually no dead spots. In other words, virtually all of the coolant came in direct contact with a tube wall. However, because the
tubes were so tiny, even the smallest particle could cause them to clog thus decreasing the overall efficiency of the radiator.
In the 1980's, Ford attempted to improve the cooling efficiency of their radiators by utilizing computer technology. What Ford learned was that
improving the cooling efficiency would require utilizing wider tubes. This meant that still a greater tube wall thickness would be needed to prevent
ballooning. For example a 1" tube would require a wall thickness of .015" which was over twice the thickness used on a 5/8" tube.
At a time when auto manufacturers were trimming weight on all their vehicles, the increase in weight that resulted from the increased tube wall
thickness was unacceptable.
The question that manufacturers were faced with was "How can a radiator be built with increased tube width, increased tube wall thickness and
still end up being lightweight?". The answer - ALUMINUM! An aluminum radiator built with 1" wide tubes with a .016" tube wall turned
out to be approximately 60% lighter than the same copper brass radiator. The 1" tube increased direct tube - to-fin contact and cooling capacity
by roughly 25%. Therefore, a 2-row aluminum radiator with 1"
tubes is equivalent to a 5-row copper brass radiator with 1/2" tubes. The state of the art engineering advantages of the increased tube-to-fin
contact are far superior to the lead joint found on copper brass radiators. The welded aluminum construction also proved to be stronger than the lead
- soldered copper brass radiator. Today all vehicle manufacturers incorporate aluminum radiators with wide tubes in their designs. GM, for instance,
offers an aluminum radiator with 1-1/4" tubes. Mercedes Benz uses 1 1/2" tubes.
Copper is a good heat conductor, but solder required to bond the tubes to fin creates an insulation point that prevents some heat transfer. Aluminum
tubes are welded rather than soldered to the aluminum tanks, providing a more efficient conductor for cooling efficiency.
The strength of the materials is one difference between aluminum and copper. The copper tubes carrying the coolant must be very thin to keep a copper
brass radiator cooling efficiently. Since copper is relatively weak, the tubes must be narrow in order to prevent the internal pressure from swelling
or exploding. Aluminum is much stronger, allowing the use of considerably wider tubes. Wider tubes allow more direct contact between the fins and the
tube, increasing the radiator’s capacity to dissipate heat away from the engine.
Aluminum radiators are commonly recommended and preferred for the demands of high performance applications.
Another important benefit of aluminum is its resistance to damage. SCP goes the extra mile to supply the GRIFFIN rugged, durable, high performance
radiators. Every GRIFFIN radiator is reinforced with a special high temperature epoxy, which provides additional tube to header strength and assists
in the prevention of vibration failure. This process is Q1 approved by Ford Motor Company, one of the toughest quality standards in the industry.
The intercore structure is furnace brazed at temperatures in excess of 1100 degrees Fahrenheit. This unique GRIFFIN manufacturing process also anneals
the tubing, making it flexible to resist puncture or split damage when assaulted by smaller debris found on a racetrack. Aluminum tubing tends to bend
rather than tear or split. In many cases, the GRIFFIN manufacturing process is the difference between finishing a race and experiencing an expensive
failure.
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avagolen
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| posted on 9/3/10 at 12:16 AM |
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WOW... Thats very interesting...
I suppose that is a good reason to use ally rads in our kits then.
[Edited on 9/3/10 by avagolen]
The Answer for everything, but never the last word....
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procomp
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| posted on 9/3/10 at 12:56 AM |
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Hi
So why on earth are people having to use alloy rads with 30% bigger surface area to cool there engines to the same temps as a good old copper brass
unit. The 30 % bigger alloy unit is still lighter by some way. But excluding weight. That lot doesn't quite stack up in the real world.
Cheers Matt
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v8kid
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| posted on 9/3/10 at 02:43 AM |
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Very,very interesting.
I also didn't know that people were using 30% bigger radiators when changing from copper to alloy I always assumed that the change was due to
the copper rad not working properly due to increaced power, clogging up of waterways or whatever and guys took the opportunity to upsize. Perhaps the
30% rule is just a fallacy?
Cheers
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02GF74
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| posted on 9/3/10 at 07:36 AM |
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hmmm, think I have seen something similar before, see if I find it... but
Copper is a good heat conductor, but
solder required to bond the tubes to fin creates an insulation point that prevents some heat transfer. Aluminum tubes are welded rather than soldered
to the aluminum tanks, providing a more efficient conductor for cooling efficiency.
hmmm, but the main cooling is water to the tubes not from header to the tubes - I'd be surprised if that makes more than a couple of percent
difference.
Since copper is relatively weak, the tubes must be narrow in order to prevent the internal pressure from swelling or exploding. Aluminum is much
stronger,
pretty sure that is not true, not when compare dimensionlay as opposed to by weight - the radiator may be made much stronger by using thicker
aluminium tubes but be lighter due to the weigh of aluminium.
BUT nottice is is blurb from a manufacturer - if their main product line is aluminium radiators, they are not gonna say copper is superior.
no mention of cost - I'll bet aluminium ones are cheaper to make too, especially the ones with the plastic headers, whcih I presume these are -
as apposeto all alloy - hence maybe where the 30% comes in due to the insulating properties of the plastic?
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rf900rush
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| posted on 9/3/10 at 07:42 AM |
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Surely the Ali Rad would depend on it's application
Car makers would be biased towards cost.
Race Rads will be on performance.
Later this year I will be finding the difference for mysef.
At the moment running a Suzuki swift Copper rad on a ZX12R, which struggles.
Next will be the popular Ali Polo Rad.
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iank
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| posted on 9/3/10 at 08:15 AM |
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A lot of people with cooling problems in locosts find air management* to be more important than the core material.
* i.e. making sure all the air from the nose goes through radiator by sealing around the edges.
--
Never argue with an idiot. They drag you down to their level, then beat you with experience.
Anonymous
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Strontium Dog
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| posted on 9/3/10 at 08:21 AM |
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quote:
Originally posted by 02GF74
Since copper is relatively weak, the tubes must be narrow in order to prevent the internal pressure from swelling or exploding. Aluminum is much
stronger,
pretty sure that is not true, not when compare dimensionlay as opposed to by weight - the radiator may be made much stronger by using thicker
aluminium tubes but be lighter due to the weigh of aluminium.
no mention of cost - I'll bet aluminium ones are cheaper to make too, especially the ones with the plastic headers, whcih I presume these are -
as apposeto all alloy - hence maybe where the 30% comes in due to the insulating properties of the plastic?
I didn't put this up to start an argument but for general information. However to answer a couple of points:-
We don't use copper (well at least if you have any sense) for brake pipes as it work hardens and breaks from fatigue. Ally is more likely to
remain ductile. Alloy rads are lighter and when concerned about balance etc this may be a factor. I was quite interested in the resistance to
mechanical damage too, having picked up a stone or two over the years and having had to replace the odd rad. I have even got home on an egg more than
once. Lol!
The best rads that I have come accross such as Koyo etc are ally, and so is my massive intercooler that I have front mounted on my GT4 which has
suffered some high speed stone strikes. (Car's good for 165mph and has seen 140+ with me in it, on a track of course)
It is also true to say that it is not the first thing I would worry about, my 300 BHP 2L turbo'd engine has a cooper core with plastic heraders
and works just fine on a 1400Kilo four wheel drive car. It does have two suckers pulling air through but these are gonna be redundant over 30mph!
If I had the dosh and a suitable alloy rad was to hand I'd use it every time, if not I'd go with the rad that did the job!
All IMHO of course!
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Strontium Dog
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| posted on 9/3/10 at 08:24 AM |
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quote:
Originally posted by iank
A lot of people with cooling problems in locosts find air management* to be more important than the core material.
* i.e. making sure all the air from the nose goes through radiator by sealing around the edges.
Excellent and much overlooked point. Getting the air through and out of the bay is key! People often ask about the vents in my bonnet and think they
are there to let air in, Wrong! The air comes in the front through intercooler and then rad and the rads are shrouded to duct as much of the cold air
through the cores as possible.
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mcerd1
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| posted on 9/3/10 at 09:17 AM |
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quote:
Originally posted by 02GF74
Since copper is relatively weak, the tubes must be narrow in order to prevent the internal pressure from swelling or exploding. Aluminum is much
stronger,
pretty sure that is not true, not when compare dimensionlay as opposed to by weight - the radiator may be made much stronger by using thicker
aluminium tubes but be lighter due to the weigh of aluminium.
that depends on the grades of copper / aluminiumn and the heat treatment / work hardening thats been done
the proof stress of anealed copper can be as low as 60 MPa (most alluminium alloys start around double that)
but thats missing the point, all the old copper rads that I've come across weigh a ton - the first time I picked one up I thought it was still
full of water 
were as the alloy ones that do the same job weighed less than half that 
-
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procomp
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| posted on 9/3/10 at 09:46 AM |
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Hi
Theres no arguing. Just that what is found to actualy happen in practice does not necessarily stack up with what was written.
Cheers Matt
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Confused but excited.
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| posted on 9/3/10 at 11:56 AM |
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An 30% larger aluminium alloy radiator may be lighter on the bench but when it is in the car it has 30% more water in it, so logic dictates that it
will actually add to the overall weight of the car, not make it lighter.
Tell them about the bent treacle edges!
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MikeR
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| posted on 9/3/10 at 12:10 PM |
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what do formula 1 use?
We're all constrained by material availability and price - even in the sorts of race series some of us partake in. The 'best'
solution is likely to be formula 1 / top of the top motorsport / etc.
Once you know the answer then the question is then why do they use that instead of ali or copper or what ever else we can get our hands on???
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Strontium Dog
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| posted on 9/3/10 at 12:26 PM |
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quote:
Originally posted by MikeR
what do formula 1 use?
We're all constrained by material availability and price - even in the sorts of race series some of us partake in. The 'best'
solution is likely to be formula 1 / top of the top motorsport / etc.
Once you know the answer then the question is then why do they use that instead of ali or copper or what ever else we can get our hands on???
Alloy is what F1 uses, Check this out
http://www.grandprix.com/ft/ft00298.html
Pants that doesn't work as a link? Can someone make it work for me?!
[Edited on 9/3/10 by Strontium Dog]
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franky
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| posted on 9/3/10 at 12:27 PM |
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I guess car makers now use alloy as its cheaper?
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Strontium Dog
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| posted on 9/3/10 at 12:29 PM |
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quote:
Originally posted by franky
I guess car makers now use alloy as its cheaper?
And since when have F! teams worried about cost? We should see what Kia use for cost effective purposes, then burn all Kia's!
[Edited on 9/3/10 by Strontium Dog]
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MikeR
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| posted on 9/3/10 at 12:33 PM |
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I hate contradicting Matt (Procomp) as invariably i've found him to be correct.
A not very quick google has pulled up the following results.
http://www.f1technical.net/articles/4 - near the bottom it states,
"While in this picture the radiator is covered with a protective hose, it is not during running as air passes through the aluminium fins of the
radiator."
http://www.azom.com/news.asp?newsID=9721
All about honda using aluminium radiators
I haven't found anything that states what the radiators have to be made out of although i did find a nice article from denso radiator division
in yorkshire.
edited to add.
So F1 uses ali. Not sure that helps really. The question now is why does real world experience (matt) find copper radiators more efficient than car
based ali radiators ????
[Edited on 9/3/10 by MikeR]
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BenB
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| posted on 9/3/10 at 12:46 PM |
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F1 isn't really applicable.
when you're travelling at 200mph and rarely stopping for longer than six seconds the cooling system required will have different requirements to
cars built to go max 70mph (officer) and sat in traffic jams in the middle of summer.
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MikeR
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| posted on 9/3/10 at 12:58 PM |
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the point for f1 is they'd use the best - if they used copper argument over.
So they don't - it reverts back to why does Matt find in real life copper better than Ali.
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iank
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| posted on 9/3/10 at 01:27 PM |
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quote:
Originally posted by MikeR
the point for f1 is they'd use the best - if they used copper argument over.
...
BenB's point is they use the best for their application, which may or may not be the best for other applications back down in the real world.
(I agree they'd use tiger skin and rhino horn radiators if it gave them a few 100th's of a second advantage )
--
Never argue with an idiot. They drag you down to their level, then beat you with experience.
Anonymous
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Strontium Dog
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| posted on 9/3/10 at 02:44 PM |
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As I said, I didn't mean to start a hot debate, but on the subject of F1 where efficiency is the no.1 priority, I believe they would use what
gives the best ratio of cooling to wieght inc. water carried etc.
The only other consideration would be will it last the race out or will it pop or a 160mph pebble be the end of it!
If the cost is not prohibitive I'd go for the most efficient and tough solution myself. I do however see an advantage to an old fashioned brass
and copper cooler and that is that you can fix it with a blow gun and some solder. Try that with an ally rad!
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franky
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| posted on 9/3/10 at 04:12 PM |
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quote:
Originally posted by Strontium Dog
quote:
Originally posted by franky
I guess car makers now use alloy as its cheaper?
And since when have F! teams worried about cost? We should see what Kia use for cost effective purposes, then burn all Kia's!
[Edited on 9/3/10 by Strontium Dog]
I said car makers... not boring f1 teams
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franky
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| posted on 9/3/10 at 04:14 PM |
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Just to add, cheapest ally rad for my application. £275 inc vat.
Triple cored copper one £110..
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D Beddows
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| posted on 9/3/10 at 04:59 PM |
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lol, nothing wrong with a copper core rad....cheaper too.....aluminium's lighter but there are SO many other variables with this it's not
just a a simple 'oh it's lighter and more modern like an F1 car so it must be better' type thing. You might save a couple of pounds
but you'll spend a couple of hundred quid doing it for little to no gain on 90% of cars....
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