Radiator: Aluminum vs. Copper? (time-critical)

[Sean]

OK, I am on my way in a few minutes to Brice Thomas Radiator in Gadsden, AL (AKA CG&J, recommended by Don Fairchild).

They have quoted me around $1,800 to recore either with aluminum or copper/brass.  They are agnostic, but when pressed recommend the aluminum for its better cooling ability.

All my research shows this is principally a religious debate, with proponents on either side.  Here are my questions for the group:

1. Has anyone switched to aluminum?  How did it work out?

2. Does anyone have a good reason why I should go one way or the other based on either the specifics of the Detroit engines or the types of coolants and SCAs we run in them?

3. Has anyone had a bad experience either way?

I will need to make my decision in perhaps three or four hours, when I should be in Gadsden with the radiator.  I'll get the responses on my phone; post them here or email them to me, whatever is convenient for you.

Thanks!

-Sean
http://OurOdyssey.BlogSpot.com

[Lin]

I once had a job for a radiator company many years ago.  At that time, aluminum cores were not repairable.  Has that changed?

[luvrbus]

Sean, the only aluminum radiator I ever owned is the one in the Lexus had a few problems with it mostly the tanks,but in my trucks the plastic air to air coolers lasted longer than the aluminum go figure seem like they were always cracking from the vibration,I think I would go with copper 


good luck 

[bevans6]

I don't know how they would attach an aluminium core to the brass header tanks that you probably have on the old radiator, but they probably have a new-fangled way to do that.  A lot of new radiators have crimped/epoxied joints onto plastic tanks.

Copper cores are heavier, dissimilar metals used in construction/repair can cause internal corrosion (the solder, basically), they transfer heat better, they are easier to repair (torch, flux, plumbers solder on the side  of the road, done that before), and they can be repaired properly by the fast dying breed of old time radiator men.

Aluminium radiators can be custom made in almost any size, shape and configuration you can buy a core for.  People (me, sometimes) get a core and weld up custom tanks for the ends.  They are very light, and seem to last a really long time in race cars, but I don't know about buses...  Corrosion is an issue, you need to have the right antifreeze.  Most aluminium radiators that I have seen fail had the crimps where the plastic header tanks are attached leak, or had large pieces of race car stuck through the middle of them.

I would decide based on your evaluation of the technical method to attach the header tanks to the core.  I'd have to be really convinced that an aluminium core would be well fixed to the old header tanks.  Soldering one on to a copper core is simple for an experienced tech.

My 2 cents, anyway.

Engineering oriented discussion group http://www.eng-tips.com/viewthread.cfm?qid=61247&page=7 has a few interesting tidbits hidden in the thread, for new construction anyway.  In your case I think even more now that the method the shop has the most confidence in, if your engineering spider sense agrees, is the best idea.  One thing to research if you want to is the compatibility of the required anticavitation additives in the anti-freeze for you V92 wet liners vs that needed to make an aluminium core last a long time...

Brian



Brian

[Hard Headed Ken]

A friend of mine was a Design Engineer at Mac truck a few years ago when I was building an oversize radiator for my 4104 for my 6V92 swap. He said on paper aluminum has better thermal transfer properties but when they tested the same size radiators side by side the copper always performed better.

I used a copper core with dimple fins. I made the tanks from 1/8 mild steel and never had any overheating problems.

The slit fin design design may have cooled better but I thought any gain would have been quickly offset once the tiny slits were filled up by trash and dirt kicked up by the rear wheel.

Ken

[belfert]

It seems to me a big reason manufacturers use aluminum radiators is due to reduced costs.  Brice Thomas Radiator seems to be charging the same for aluminum or copper.

[luvrbus]

Labor cost for a aluminum constructed radiator will offset the material price I was surprised the cost being the same I ordered aluminum air to air coolers that cost that much

good luck

[skihor]

Copper conducts heat better than aluminum.
http://www.arrowheadradiator.com/14_rules_for_improving_engine_cooling_system_capability_in_high-performance_automobiles.htm
Don & Sheila

[bevans6]

The thing that makes it hard to determine which will be better is that while copper in theory conducts heat better than aluminium, the radiators made from the two materials use different enough design details that a direct comparison does not yield a clear winner.  Sometimes a copper design with more tubes and denser fin count is better than a given aluminium design, sometimes the aluminum design out performs a different copper design.  Sometimes the air flow requires less dense fin count, giving up maximum heat transfer for a different benefit.  It's virtually impossible to pick based on a recore of an old rad of uncertain design, cores of completely unknown specification, and not knowing the way the shop will assemble it all together.  Only thing certain is it's gonna cost a lot, and it's gonna be a lot better than what he had!

[Sean]

Well, the deed is done.  I decided to go with aluminum.

The overarching reason for that decision was the fact that they make the aluminum cores in-house, but the copper/brass one would have to come special order from Texas by truck freight.  They might be able to have the aluminum one done on Thursday some time, whereas they wouldn't even have the core from Texas until sometime Friday.

The other reason is that almost everyone agrees that aluminum can be made more efficient (yes, I am aware that copper has a lower specific heat than aluminum, but the mass of each assembly is also different, along with fin spacing, tube cross-section, and other factors that make direct comparison on this basis alone impossible).  Given that our engine runs hot anyway, I am willing to accept some of the other downsides of an aluminum core to get just a bit more heat-shedding ability.

Where people tend to disagree is on durability and resistance to corrosion.  Some swear copper/brass corrodes faster (and this is the reason these cores must be painted) while others swear aluminum corrodes faster (galvanically, especially in the present of salts).  Most evidence either way seems to be anecdotal.

There is a concern about fin durability, but this has more to do with thickness and construction than material.  The shop showed me their serpentine aluminum fin construction and I was satisfied that they will not flatten/dent in normal use.  My radiator is set well back from the exterior of the coach, so FOD is unlikely anyway.

I am relatively confident that the new radiator will last at least as long as I own the coach, and will likely make it the same two decades the original unit did.

I will post photos of the completed unit on the blog when I pick it up.

Thanks to everyone who chimed in.

-Sean
http://OurOdyssey.BlogSpot.com

[bevans6]

I wouldn't mind having the contact info for the shop you are using, if they make their own aluminium cores.  I have a seriously hard time finding cores for when I want to make a custom radiator for some old vintage car.  I would love to have a place I could just order a core from! 

Brian

[Chopper Scott]

I guess we all will learn something here. Basically by failure, success or not much improvment. Keep us posted...

[Busted Knuckle]

I wouldn't mind having the contact info for the shop you are using, if they make their own aluminium cores.  I have a seriously hard time finding cores for when I want to make a custom radiator for some old vintage car.  I would love to have a place I could just order a core from! 

Brian

Brian,
Here is the link to where Don Fairchild suggested. (I also found out today that it is the same place that my ex-neighbor and hot-rod guru Mark Jones uses to build his custom radiators for the one-off custom creations he builds.)

Sean (& others) Don explained to me that with all other items being either equal or close too equal that he'd still go with the aluminum in order to lose 40-50 lbs on a radiator of that size. Like he said we all know weight is an issue with all our buses.
  BK 

[boxcarOkie]

[quote Like he said we all know weight is an issue with all our buses.
 BK  
[/quote]

Well smack my butt and call me Judy!  

When I posted Fuelish Moves awhile back (http://www.busconversions.com/bbs/index.php?topic=19991.msg218209#msg218209) I was poo-poo'ed and told that weight was no big deal.  

Now it has turned around and it is?  I am confused (Isn't life grand?).  Now excuse me Y'all, I am going on-line and getting a quote on the material for my new granite floor.

BCO

[pabusnut]

In my mini-bus(actually a Chevy Suburban), I had an aluminum radiator go bad in the Appalation foothills of WV, while taking my daughter to camp last year.  Of course the new 4 row radiator was only $10 more than the factory 2 row one, so I got it. 

When I did a failure analysis on the "bad" radiator, I found that the aluminum core was fine, and so were the plastic tanks, but the rubber seal between the two on the top had failed.  Since they are crimped over the plastic tank, I don't think there is any real way for us shadetree mechanics to effectively repair these radiators.  The upside was that the replacement radiator for the thing was half the price of the one I put in my Volkswagen TDI!

Steve Toomey
pabusnut