Originally Posted by 89.5 Esprit SE
If the fans are set to come on at a temp like 95-100, then the engineers did that for a reason. If you drive your car hard it will tend to run at the higher temps. So I think it is quite safe. Most modern turbos will limit boost if the temp is too cold not too hot. The 4 will not allow full boost below about 82. Clearly you don't want to run too hot, and there are pros and cons of both ends, but if the engine is designed to run at a certain temp then it should be run at that temp.
You do need to ensure that everything is operating correctly and that you have the proper thermostat, since the latter is mechanical.
If the thermostat openened and closed at your ideal operating temp then it would be cycling very frequently and you would not get proper radiator flow which is how you get proper cooling. Remember that the fans don't generally operate to keep the radiator cooling except at slow road speeds or very high ambient temps. If you are driving at 80mph your fans won't add too much air flow.
I clearly don't have anything better to do but debate fan on/off logic...
"If the fans are set to come on at a temp like 95-100, then the engineers did that for a reason."
Same reason they designed the radiator fins to clog up? Same reason the whole rad/fan setup needs to be replaced to really survive for hot weather climates? Same reason they designed liners to fail? Same reason they kept the crap Renault gearbox?
They're not perfect. And I do think vbtodd's theory of letting the car run hot at idle speed to improve the ability to pass emission is a real possibilility, and not that they were thinking they could make sure the car would last past the whopping 2 year warranty period by making it run hot at slow speeds.
"If you are driving at 80mph your fans won't add too much air flow."
Great point. So if air is blowing through the front radiator opening, the fans are going to draw very little current since they don't have to work to push the air. Basically, you are turning off the fans even when they are on at high speeds. That's how electric motors work. No load = no power to drive them. In fact, if the air flow was strong enough, it would charge the battery (wind mill). So there's David's duty cycle problem solved!
Keep in mind the AC switch just checks the pressure level in the AC system to know it's on and then turns on the fans regardless of what the engine wants. So the AC has the fans on all the time even if your driving at 70mph when you live in Texas and you have +100degF and a huge greenhouse for a front windshield.
But, hey, run it hot if you like!