Vehicle speed vs fan speed question
04-08-2010, 03:06 PM
#1
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Vehicle speed vs fan speed question Does anyone know or have a way of finding out this value?
What value you ask?!
I want to know at what vehicle speed it is useless to have your fans on for cooling purposes? I have a manual switch for the high/low speed fans and I always wonder when I should turn them off or not. If you're stopped it's obviously a benefit to have them on, but at what speed are they overcome by the incoming air?
Any help would be awesome.
What value you ask?!
I want to know at what vehicle speed it is useless to have your fans on for cooling purposes? I have a manual switch for the high/low speed fans and I always wonder when I should turn them off or not. If you're stopped it's obviously a benefit to have them on, but at what speed are they overcome by the incoming air?
Any help would be awesome.
04-08-2010, 05:59 PM
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Your fans cannot flow enough air to match 60-65+mph. Fan clutches typically start to free spin again after 60-65+mph. Was actually thinking about this today as well.. I think in the newer vehicles, there maybe a programing parameter in the ECU to shut the fans off when the vehicle goes over 60 or 65.
04-08-2010, 07:35 PM
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i bet its more like 30 mph or so that they turn off. But I have to ask why did you take out the automatic operation of the fan? I understand having a way to override to turn them on, but you dont want to override the factory option to turn them all the way off.
04-08-2010, 08:06 PM
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Oh no no no, I didn't in any way affect their auto operation. I have the manual switch PRIMARILY for when the car is off, I can turn the fans on (like in the staging lanes). I have an LED wired to the fans so that anytime the high speed comes on (whether auto, or with my switch) it lights up. It's neat to see the driving conditions that make them come on automatically.
You're right, the fans do come on at a certain engine temperature (that can be tuned). Because of that, they aren't on all the time. My question is, at what vehicle speed it's not worth it to have them on purely from a CFM point of view.
That's to say, the high speed fans flow xCFM and 60mph flows >xcfm. (or whatever speed it is)
I see that a couple people got what I meant, sorry if i was unclear.
You're right, the fans do come on at a certain engine temperature (that can be tuned). Because of that, they aren't on all the time. My question is, at what vehicle speed it's not worth it to have them on purely from a CFM point of view.
That's to say, the high speed fans flow xCFM and 60mph flows >xcfm. (or whatever speed it is)
I see that a couple people got what I meant, sorry if i was unclear.
04-08-2010, 08:49 PM
#6
There is def an equation for it... I would try googleing it or something. I'm pretty sure I have read it on one of the mags like GM high tech or car craft. It was a long time ago and I don't remember what issue, other wise I would go look it up for you.
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04-09-2010, 02:02 AM
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Looks like the stock settings have both fans programmed to shut off at 65 miles per hour. Fan 1 is programmed to shut off at 35 miles per hour unless it's above the turn-on temp. I don't know if GM did tests on these or not, but I imagine 65 is probably a pretty close speed at which the fans no longer cool any more than the air that the car is pushing through.
