Electric Fan

i run a fan from a volvo. ive saw somewhere that it was rated to 4000cfms. dont know if thats true but if i turn it on when im in the drive way and put my hand in a few inches infront of the ford emblem on the grill you can feel it pulling air in really hard. uses about 50amps to run the damn thing. i blew so many 50amp relays it was rediculous. finally just got a 200amp relay for it and no problems since

you want a larger fan so that it pulls more cool air faster so that the coolant chills faster and is colder when it enters the engine which is making more heat then a bone stock motor

I did the Taurus fan on my old 5.0 and my current ZJ. Never had an issue with either. My ZJ can idle with max a/c on the hottest day of the year in Tucson and never move past the 210 mark. If I turn the fan on high, and stand behind the car, I can feel air on my feet.

My buddy back in WI has a notch with a blower and uses a chevy cavalier electric fan, if that tells you anything.

As you eluded to, the electric fan is really only needed when there is no air flow moving arcoss the the radiator. At speed or on the highway the fan doesn't even need to run because the air is moving fast enough on its own. So really fan choice comes down to how you use your car....

I just swapped in a Mark Viii fan, but I live in Metro Detroit and all I do is follow other cars and stop once a mile for a red light. Plus, I wanted to be safer than sorry, even with a stock setup...

TrickStang37, you raise some good questions. I do not think I have the answers, but I would like to hear some more discussion on this, and I am going to put in my thoughts.

I would tend to think your heat production would be more linked to fuel input than to maximum HP. So if your new motor needs more fuel at idle and in traffic (because it has a blower, is tuned for high RPM so it is less efficient for daily driving, or for any reason needs more fuel than the old motor at times when overheating is a problem) then I would think you would need an increase in cooling capability to match.

If (as an example) your new motor does not require any more fuel than the old motor for conditions where cooling is a problem (at idle or in traffic), then there would be no reason to upgrade the cooling system. Like, for example, if the only change was a nitrous system used for short bursts.

I personally would splurge on the cooling system though. It is a sick feeling to be stuck in a traffic jam in the summer, watching your temp gauge rise, and knowing there is nothing you can do about it.