There is a huge range in rads. Amoung the "made for water cooling" rads they start with the "micro" rads that are just big enough to fit a 80mm fan on them for cooling. Micro's are long on look and short on performance. The other exteme amoung the custom made for water cooling is the 120.3 rad which can take 3 120mm fans per side.
Heater cores offer the best of performance, but require some modding skills to alter the cores inlet/outlets and custom make shrouds to mount the fan(s) on. A large heater core that can take dual 120mm fans per side offer massive cooling. The sinlge pass core from chevy pick ups 69-72 offer very low resistence to flow and thus extreme cooling potential, they can take dual 120mm fans per side.
|