Lets Talk Radiators Because there is some BAD information out (just replaced mine)

[LEVY]

Believe it or not, black radiates heat better than bare metal, I' m talking about a thin layer of black and not a 1/2" tick coat of paint.

Just look at the heat exchangers installed on electronic boards, if they are painted, they would ne black.

LEVY

How can applying a coating of paint, regardless of color, be more efficient at radiating heat away from the metal than just leaving the metal bare? There is bound to be retention of heat by the coating that wouldn't be there if the metal was unpainted....

[DMCMW Dave]

Something I've always thought curious in this discussion is all the hoo-ha about "triple core". Marketing BS in my opinion.

Actually what you are looking for is the surface area presented to the coolant. One wide core would present more surface area than three narrow cores (with all else equal). It is probably more difficult to manufacture a wide single core.

The overall thickness of the radiator, and the density of the fin tubes (i.e. how many rows as Nick pointed out) and the density of the fins between the tubes has a much bigger impact on the ability of the radiator to transfer heat than does the mere number of cores. Obviously overall size makes a difference too but you are usually limited to the original dimensions.

If you look at the OE DeLorean radiator you'll see that it is MUCH denser, with more rows, than just about any of the others, and certainly more dense than the common aftermarket brass one. Too bad about the plastic tanks, as I have yet to see the core on an OE radiator fail. It is the joint from the plastic tank to the core that fails 100% of the time.

The down side to very dense radiators is that it is easier to plug them up. Not a big deal on a well-maintened car, but we have seen DMC radiators that don't flow well and will cause the car to run hot a highway speeds.

[David T]

The implication of "triple core" is that you are getting more than single or double. The problem with that logic is to have the same external dimensions each of the 3 cores are smaller so you wind up with less surface area available for heat transfer then a single or dual core of the same size. Copper is better at heat transfer than aluminum but it is heavier and more expensive. Painting the radiator does nothing to improve heat transfer except prevent corrosion which would impede heat transfer which is why radiators get painted. They are usually painted black so you can't see anything shiny when you look in the grill. Denser is always better but they do tend to get plugged up faster. A much bigger problem on Lotus's. They get so plugged up with tiny pebbles and other road debris that the motor will overheat. It is also very difficult to clean them unless they are removed and on a Lotus that is a big job!
Bottom lining this, ANY radiator you put in is going to be an improvement over the 30 year old POS that is in there now. If it isn't leaking (it probably is but you haven't noticed it yet) it soon will be. The big danger in still keeping the OEM rad is that one day the left tank will blow off in a spectacular cloud of steam and if you do not IMMEDIATELY stop the car you will also be replacing the head gaskets. Every owner should inspect the left tank seam for any signs of green. You look at the radiator behind the left, front wheel and through the left fan at the backside of the rad. If you still have the OEM rad don't even bother inspecting it, just replace it.
David Teitelbaum

[Nicholas R]

I think the bottom line with radiators is that you cannot get away with not coating copper/brass radiators, otherwise you get bad oxidation. Painting aluminum isn't necessary and would just give another layer of material to transfer heat through. Really you want as little material as possible because you're transferring WAY more heat via forced convection than radiation.

Also, I think no matter what, if you say something has 3 cores, whether it's better or not, it damn well better have 3 cores.

[DeLorean]

Overall thickness, as well as the spacing of the fins is what's critical here. Automotive radiator cooling capacity should be rated in BTU's based on universal coolant flow amount, but no one does this...

[DMC5180]

I have the so called "heavy duty" 3-row brass (made by Aftermarket Radiator Exchange, Inc) or ARE. They also made a 2-row brass version . The 3-row was about 1/2 inch thicker than NOS and I did have to trim the FAN shroud slightly where it gets close to the crumple tube ends. I've had it in the car 15 years without issue. I plan on updating to DPNW fans this fall. When that happens, I'm going to down size the radiator back to the 2-row with the consensus being it is more efficient and it FITS better.

[r00b]

Can we have metal tanks put on the sides of our old radiators?

[David T]

The short answer is no. The long answer is, it is technically possible but no shop is going to spend the time with the very high probability that it will leak. It is very hard to get the old core clean enough to prevent porosities in the weld. Besides, it is over 25 years old, long past it's intended design service life. Consider the old radiator scrap metal.
David Teitelbaum

Can we have metal tanks put on the sides of our old radiators?

[Ron]

Something I've always thought curious in this discussion is all the hoo-ha about "triple core". Marketing BS in my opinion.

+1
I believe this comes from the old days when the Big Three made tanks with 3 rows of holes. Making a 2 row was as simple as saving the extra flutes at the expense of a bit of solder that would automatically seal one set during the normal process, a bargain. (I've seen some with the 'dimples', but no holes, too.) Guess it just made sense then with one set of rubber mounts, brackets, hoses, etc to manufacture and keep track of...and cost ratios.

[DMCMW Dave]

+1
I believe this comes from the old days when the Big Three made tanks with 3 rows of holes. Making a 2 row was as simple as saving the extra flutes at the expense of a bit of solder that would automatically seal one set during the normal process, a bargain. (I've seen some with the 'dimples', but no holes, too.) Guess it just made sense then with one set of rubber mounts, brackets, hoses, etc to manufacture and keep track of...and cost ratios.

Yes - on cars like Novas/Camaros for example, you'd have a two-core on an 6-cylinder car and a three-core on a V8. Everything fit the same.