You can shove all the btu's in the radiator you want, but if the coolant is flowing faster than the radiator can dissapate them you've accomplished nothing by putting the warmer coolant back into the engine.
Nope.
The faster you flow the coolant, the better the engine cools.
Let's put this another way. You're heating the metal of the radiator by running hot water (coolant) through it. The more efficiently you can heat the radiator, the more the radiator can heat the air blowing through it. If you can heat the air, you've removed that energy from the coolant.
The thermastat was designed just for the reason to allow proper operating temp
Yes. By restricting flow to the radiator to CONSERVE heat, otherwise the radiator would over-cool the engine.
and to allow radiator time to dissapate the heat from coolant before re-entering engine maintaining the proper coolant flow.
No. Faster flow would over-cool the engine unless the cooling system is defective or under-sized.
High flow pumps aren't going to change much of anything when the thermastat is closed making the coolant sit on engine anyway. It will expell it from engine a little quicker when stat opens.
True. The high-flow pumps don't do anything better than an "ordinary" pump until the thermostat is nicely open. Then they "could" make a difference.
I think it's more important that the flow characteristics of the pump be matched to the expected engine RPM level. An engine that spends a lot of time at idle and low-RPM (but may be worked hard at that RPM level) is going to need a pump and pulley system that moves coolant at that low engine speed. Such a pump and pulley system may cavitate at high speed, losing efficiency and causing overheating. Conversely, a pump and pulley system that is designed for high speed may not pump enough coolant at low speed.
Yup, life is about compromise...
If you want more flow and don't want coolant to sit on engine, then why even run a thermostat.
The thermostat is primarily to allow the engine to WARM UP in a reasonable amount of time; and secondarily to maintain an even and appropriate temperature under varying operating conditions. The thermostat is the "throttle" for the cooling system. The throttle opens as you need to reject more heat, and closes to conserve that heat when the engine isn't producing as much heat.
The first requirement for this to happen is that the cooling system has to be able to reject the maximum amount of heat that the engine can produce--and then that "maximum rejection" is "throttled" by varying the amount of coolant that goes through the radiator. Less flow = less heat rejected to the air stream. And since the cooling system has enough capacity, the temperature is kept relatively constant.
A considerable problem is too many people have a cooling system that has too little heat-rejection capacity to begin with--and the simple-but-wrong "fix" is to shove in a thermostat with a lower temperature--or--to pull the thing entirely out. Either way, there's less restriction to coolant flow. In a radiator with top 'n' bottom tanks, the top tank is both the inlet and the tank with the rad cap; too much dynamic pressure from the water pump can overload the relief valve of the rad cap and cause coolant loss. Since crossflow radiators have the radiator cap on the suction side, the rad cap doesn't "see" the additional dynamic pressure from the water pump and so crossflow radiators don't tend to overflow like downflow radiators do when the thermostat is removed.
Result: The engine runs hot because the cooling system is always near it's maximum capacity for heat rejection--or--a downflow radiator
appears to be boiling over when the issue is too much static + dynamic pressure at the rad cap rather than too much temperature.
