Coolant Flow Rate
Looking at the previous expression, we can see that slowing the coolant down is the wrong way to go. If the heat load is constant, lowering the flow will increase the temperature drop through the radiator, making the bottom tank, or radiator outlet, temperature less than before. If the bottom tank temperature goes down, the top tank temperature must go up to maintain approximately the same average core temperature so that the heat load may be transferred to the cooling air. 
 At the reduced power setting it would rise above 190 degrees F and at 39.8 hp the engine would be overheating worse than before.  In fact, because the lower flow rate results in lower coolant velocity and less “scrubbing action” in the tubes, the average coolant temperature must rise slightly in order to transfer the heat load from the coolant to the cooling air, making matters even worse.
What would happen if we increase the coolant flow?  Will it go through the radiator so fast that there won’t be time for cooling to take place?  Not at all, from the expression, we can see that if the heat load is constant, increasing the coolant flow rate will reduce the coolant temperature drop through the radiator, resulting in a higher bottom tank temperature.  If the bottom tank temperature is increased, the top tank temperature must go down to maintain approximately the same average core temperature.  This is what we were hoping to achieve.  With the inlet tank temperature now less that 190 degrees F at the reduced power point, we can expect  that the system will be better able to run at 39.8 hp without overheating,  In fact,  because  the increased coolant flow rate results in a higher coolant flow velocity and better “scrubbing action” in the tubes, the average coolant temperature decreases slightly while transferring  the same heat load to the cooling air, further lowering the top tank temperature, resulting in better cooling performance. 
From this we see that increasing the coolant flow rate will result in better heat transfer performance.  On a Motorcross bike Radiator, sometimes the flow path and water distribution through the core are less than optimal, this is another area that HyperFlow work to design out. From 2007 we are now using CFD (Computational Fluid Dynamics is a cutting edge analysis tool that ahs evolved out of Formula 1) Software to optimize flow into the inlet tank and flow distribution to the core. HyperFlow is the only manufacturer of Performance radiators to CNC machine the tanks from Aircraft quality Alloy – meaning we can change the design of the internal tank independent to the external shape. The HyperFlow Racing Radiator is designed to improve flow rate, and the reason why we also provide complimentary Silicon hose sets that optimize flow rates.