A rad this big has unlimited flow, in PC cooling terms anyways. The end tanks are connected together with nearly 100 cooling tubes all flowing in parallel. You can stick a garden hose in the top, crank it on full blast and it will all just flow out the bottom without backing up and overflowing the top. This rad was designed to cool a big V8 engine afterall. When I look in the fill hole, I can't even see the water moving. If we assume my flow is 1.5GPM, divide that by 100 tubes and you get 0.015 gallons, or roughly 2oz per tube per minute.

The big rads that have huge restriction are the tube style rads like the Mora 2. They have no end tanks and have a single tube that winds it's way back and forth across the cooling surface. The massive tube length and dozens of 180 degree U bends create alot of restriction.