Just trying to show how surface area, material, and air flow IMO have as much or more to do with engine cooling than flow rates and radiator cores. I've raced air cooled motorcycle engines for a long time and in the late '70's early '80's high performance motocross and off-road motorcycle engines became liquid cooled and we dealt with the overheating issues and mostly (but not exclusively) the problems were caused by lack or reduced air flow. On air cooled engines it relied on the surface area of the cylinder fins, the material (aluminum) and the air flow across and around the cylinder and cylinder head fins. When we went to liquid cooled engines all we were basically doing was using the coolant as a medium to take the primary source of heat engine combustion and taking it to one or two aluminum radiators and dissipating that heat to air. No real rocket science except in air flow with radiator side panels as scoops and our engineers even came with side panel or radiator "shrouds" that had opening that created a "chimney effect" that would help remove hot radiator air from behind the radiators at slow speeds or even at a standstill. Engines are still air cooled in my opinion they just use coolant to take that heat to a radiator or air cooling area. That's why I feel or know that air flow, surface area and material are most important. Check out this air cooled, 500cc single, hemi head, twin spark plug 60+ HP motocross bike from the early '80's. Lots of aluminum cooling fin area with lots of space for air flow. BTW most liquid cooled motocross bike still use the same basic size aluminum radiators to this day. Only a few things have changed like special radiator coating rather than black paint to better dissipate heat or small electric fans on the backside of the radiators for extreme slow moving conditions. AIR FLOW IMO is a key element.