I don't really know.
Which heater core were you comparing it to?
As a gross over-simplification(1), the "cooling power" of a radiator is proportional to its frontal area. A radiator for two 80mm fans would have about 19 square inches frontal area. The ubiquitous 6x6 heater core would have about 36 square inches frontal area, so my first
guess would be... no.
I'd suggest reading
An Evaluation of the ThermoChill Radiators.
Bob
(1) Over simplification as my high school physics teacher used to do: "Physics is the science of
everything and we have only one school year. So! I will over-simplify - in fact, from time to time, I will even
lie to you...".