Keith,
    What's the difference between a radiator core and an
    air-conditioning core.
    George (down under)

    George,

    The major difference is around 300 - 400 psi in the a/c core v.s.
    around 20 psi for a radiator.  A/C cores are thicker walled round
    tubes to prevent them from distorting when subjected to the hgh
    pressures in the system.  Radiator cores can use a rectangular tubes
    with thinner walls and will have more surface area per square inch
    of radiator surface, hence better heat transfer.

    Joel

Aircon cores are also generally a thinner package, while heater cores
are significantly thicker.

Keith Wood

Thanks Keith and Joel,
The reason I ask is that there are many GM aircon cores out there being used
as radiators. Generally they appear thicker (not thinner), than the rad
cores, perhaps 3 to 4" for the GM aircon cores and about up to 2" for the
Rad cores.
I believe the suggestion to increase the pressure in the Radiator to about
24psi to protect against boil-over at altitude might put the radiator at
risk,  if it's rated at only 20 psi - would there be a safety factor built
in or would it be running dangerously close to pressure limits.
George (down under)


---------------------------------------------------------------

It depends on which one you are talking about George.
There are two heat exchangers in AC systems. One inside the
vehicle and one up front next to the rad. The one up front has
large frontal area and is thin similar to a rad.

The one inside the vehicle has frontal area constraints and aerodynamic
drag or pressure loss is not a consideration. It is dumb to use it in a way
it was not designed for. The typical car rad is a better match for
aircraft engine cooling use.

Any air/fluid heat exchanger works better if thin. The ultimate heat
exchanger has infinite frontal area with infinitesimal thickness :)
The first half does three quarter of the work.

So far nobody has blown a rad with up to 30 psi.