Quote:
Originally Posted by Sunwapta
I've always wondered why they don't eliminate the radiator or cut its size by half by just running one or two cooling lines under the car to the rear then back to the engine bay. If necessary add a couple miniature rads midway back.
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Another consideration that affects this suggestion (and the body-surface exchanger as well) is manufacturability. The assembly plant has to fill the cooling system with fluid after it has been assembled in the vehicle and is often one of the last things done before starting the engine and driving away. Filling fluids is time consuming and messy, both of which are abhorrent in a mass production environment.
Complicated fluid pathways are more difficult to fill. Air only comes out of the system at the top and if there is not a continuous path upward the system will not purge. Some factories use vacuum-fill where a considerable vacuum is drawn to purge the cooling system of air "dry" and then fill the void with coolant, but there will still be air. Inserting exchangers under the body will almost surely cause air traps and long horizontal runs of line tend to pool air bubbles without a clear upward path to an air bleed. Excessive air bleed screws make filling hard and messy, especially if tool access to the bleed screw is difficult. Even if many of these challenges can be overcome for initial production, servicing the cooling system can be dramatically more difficult as draining/filling partially wetted systems is even tougher and more likely to trap air than filling a dry system.
Folks here pay attention to cooling systems as a necessary evil that robs us of aerodynamic efficiency, but I'm pretty sure that cooling system engineers at all the auto companies are trying to please many different masters not the least of which is reliably cooling the engine (something air traps and off-putting maintenance costs don't help).