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Discussion Starter #1
I'm just curious which radiator cools better ...

The early copper radiators in the 80's C900, or the later aluminum one in my 1992 C900?

I'm not concerned with weight at all, merely cooling ability.

Radiators in general even. I've heard that, despite being a less effective conductor, aluminum is a better cooling radiator because the walls are stronger and can be thinner.

I have an 89' auto C900T and the afformentioned '92 manual C900 n/a and can theoretically swap the two. Lots of other parts are being swapped. (IE eventually the gearbox, cyllinder head, intake, etc)

If this were a repair I would have put it in the C900 section, but since it's a modification I thought it might get a better response here.

Also haven't seen the difference between copper and aluminim discussed here. So it might be interesting to get a general discussion going.

Most tuners for other auto makes (IE Subaru, Honda, Ford etc) sell upraded radiators and I rarely see it even mentioned in Saab tuning. Maybe we just have really good radiators from the factory? Maybe most of the tuned cars are in cooler climates, like Sweden?

Let's get some discussion!

Dubbya~
 

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Maybe we just have really good radiators from the factory?[/b]
Adrian W, i too am living in hot, sunny southern california. i have never had any trouble with cooling my own 92 C900 (turbo), and my (slightly) modified stage 1 upgrades have not seemed to pose much of an issue with keeping my car running at a comfortable temperature of about 1/2 of the way up the in-dash water temp gauge during the day (it was around 100 degrees F. today) and about 1/3 of the way up the gauge at night.

It is in my opinion that the factory radiators on our cars were designed to do the job well.
 

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Hiya Dubbya,
More questions than answers really, but are the two types of radiator that you mention the same size or did Saab change the size when altering the material?
Nick.
 

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It's a good Q... but I'm not so sure how much of an issue it is for C900s, which don't suffer the problem of 9000s of having a triple radiator sandwich. I've driven my C900 fairly hard during summer and haven't suffered any cooling probs, only intercooler saturation, which is a far greater limiting factor on performance.
 

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Discussion Starter #5
Originally posted by Mark E:
[qb]It's a good Q... but I'm not so sure how much of an issue it is for C900s, which don't suffer the problem of 9000s of having a triple radiator sandwich. I've driven my C900 fairly hard        during summer and haven't suffered any cooling probs, only intercooler saturation, which is a far greater limiting factor on performance. [/qb][/b]
I'm working on the intercooler bit, but my Saabs have always run rather warm.

Suprisingly this turbo seems to run slightly cooler than the n/a Saab. Part of that is due to lower compression. (Higher compression acts like boost pressure, but without an intercooler to cool things off.)

I believe the dimensions are more or less the same as well, and apparently this turbo Saab has had a special relay mod that a Saab tech once told me about. Once the temp kicks the fans on, it kicks both fans on at once instead of just one.

Between copper and aluminum, I've heard this debated for some time. And as for larger radiators, has anyone tried one on a 9000k with the more complicated cooling system?

Dubbya~
 

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I did a bit of a search for custom car radiators- if one believes the info on the sites of firms selling them, aluminium rads cool about 50% better than the brass/copper equivalents. It's certainly got me thinking about a possible alternative for my 9000.
 

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Discussion Starter #7
Does your 9K use a brass/copper rad in it?

If all that is really true, perhaps it wouldn't be a bad idea for me to eventually swap to my Aluminum rad out of the '92 Saab.

Then again, so far the Copper/brass one seems to be up to the job just fine. But the cooler the car runs, the more
it will make, so I'm getting curious about radiators as well. Especially since it's been over 90 degrees F (32C) the last week or so. Heck, last night at midnight it was still 75F (24C) outside.


Dubbya~
 

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sorry to start getting a bit off-topic here... Adrian W, i am wondering whereabouts in southern california do you live? I am in the south Orange County area... i am curious as to whether you are living in the coastal or inland areas?

i was in the car most of the day yesterday, the dashboard temperature gauge sat right around halfway all day, whether i was cruising at 85mph on the freeway or caught in traffic, doing stop and go...[/b]
aluminum is used as a heatsink on your computer's CPU, along with a cooling fan... to the best of my knowledge, aluminum will disipate heat faster than brass or copper. i believe it is not nearly as dense and thus is able to move heat through it faster. if you were to use your radiator as a heating element, i would presume that a copper/brass unit would be more up to the job, as it will hold its heat longer than the aluminum unit would
 

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Discussion Starter #9
I actually saw something on the argument quite a while back.

Copper conducts roughly twice the heat aluminum does, BUT .. it's quite a bit weaker. So in a pressurized system copper has to be more than twice as thick, which cuts its cooling power in half.

Also brass doesn't conduct as well, and I'm pretty sure radiators are not pure copper. (Brass being an alloy of copper and zinc.) At any rate, eventually I think I'll swap the two. I have time, for now.

Dubbya~
 

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I think the other factor Adrian is that copper has a higher specific heat capacity than aluminium. ISTR formo some long time ago when I did any thermodynamic theory that to conduct thermal energy efficiently between two different liquids/air you need somehting with high conductivity but low SHC. Of course someone could be along very soon to tell me this is a load of old rubbish...
 

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I thought it was just a case of which supplier could make a radiator the cheapest - and guarantee the cost over a contract period.

Aluminium price is much less volatile than copper, and cheaper.

Aren't there some all plastic rads about now? Not just the ends.
 

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When working with computers and thir cooling systems (including water cooling) we have found that copper cored radiators and copper cooling blocks cool the most efficiently, but this is in a very low pressure system. on top of a copper radiator, a BLACK copper radiator cools even better than a natural finish one. Aluminium is easier to manufacture as no soldering is required, so the cost is down, but for raw materials, aluminium is actually more expensive (not by much, but still, it costs more). its only because the Al rads have less material than the Cu rad that they are cheaper (and work just as well).

i have a c900 8v n/a and a 9000T.. the c900 has a copper rad, the 9000 has an aluminium rad. I get > 45°C here, and they both only ever get (or got in regards to the now dead c900) just above 1/2 way on hot days with the A/C on...
btw Adrian W... my c900 has the same feature with the cooling.. when the engine fan comes on, so does the A/C fan.... pitty the 9000 doesn't do that aswell!
 
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