the engine with the best cooling ive seen with my own eyes is newer ktm. the head isnt a big pompous looking thing with gallons of water but rather its fairly small with passages that mimic the combustion chamber top side. alot can be learned from the oem manufacturers and their latest and greatest designs. why aftermarket companies continue to make these big heads with rediculous amounts of water capacity is a mystery. its likely their heads have little to no testing
I agree.
Making a head or cylinder hold more coolant in the water jacket does not improve the heat transfer from the head and or cylinder to the coolant flowing through them. Adding volume to the coolant system does allow one to run at lower speeds for a longer period of time before the coolant will reach the a critical temperature for a given engine.
The difference in coolant volume from an OEM head to one of the aftermarket heads that boast their head design holds more coolant is insignificant in regards to the amount of time it would buy you before the coolant reaches a critical temperature.
If all we were concerned about was coolant temperature, we could remove the radiator and add a 5 gallon coolant reservoir and let the engine just circulate the coolant through the engine and coolant reservoir. On a 50 hp engine running wide open we could run it for about 15 minutes before it would boil the coolant without a radiator cap. Install the radiator cap and it would now take about 20 minutes to boil the coolant.
