My 2 cents...
I have gone through horror stories with electric fans...
I'm very paranoid when running just 1 fan.
Electric fans will fail.
I've had them fail on the street, and I've seen them fail on the track.
Either or will ruin your day.
I'm a firm believer that you should be running twin fans.
Luckily, Spal makes one - I believe Be Cool rebadges these things?
It's like 2800CFM for twin 13" units?
(I don't see it on the Be Cool website.
)
The downside is that these things pull some serious current.
Minimum 15A - 20A *per* fan.
Can you imagine running both of them just idling???
Yeah, upgrade alternator is a must.
As for the numbers...
IME, the stock thermoswitch used to switch on around 225F indicated on my SPI water temp gauge.
The gauge, calibrated down to actual temp via an IR gun, is around -10F in those ranges, so actual was around 215F.
I used to run it triggered directly by that stock switch...
...until it FAILED.
The switch would be intermittent and then one day, it just stopped turning on the fan.
Yes, the circuit was isolated via a Bosch 30A relay.
Luckily, I always run a manual switch, so that saved my ass.
Currently, I have a *single* fan (I've got the Spal / Be Cool sitting on the side) triggered by my Haltech E8.
(i keep one eye on my water temp gauge all the time when I drive.)
Turn on is a lofty 230F and turn-off is at 205F.
I don't want the stock thermostat "clapping" due to too low temps, so I try and float it 10F higher than it's rated at.
IME, things don't get toasty until the temps hit 240F - 245F.
At 240F - 245F, you can SMELL the engine burning - good visceral sign that something is WRONG.
Yes, people will balk at those numbers, but I will stand by my experience.
We've had our race cars run up to 250F - 260F intermittently without puking seals.
This is not possible, right?
I'm living proof that I can run at those kinda numbers.
I've been running my Haltech E8 like that for the past 5 years so far...
I've got these numbers up on my website here:
http://fc3spro.com/TECH/MODS/EL/GAUGES/wtemp.htm
-Ted