Electric Fans - Who Needs 'Em>

Bullshark said:
Kid, Now I remember....back then you dealer mechanics said if it's not pegged over in the red ....not a problem. BB are supposed to run hot! :lol:

Bullshark
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:lol::lol: Busted me!

Seriously, some people forget that there's an optimum operating temperature range. I've always heard 180-200F is optimum. I don't think I would get too worried unless it went over 220F. The CE article that I fell in love with states that a system with a 15 lb cap and 50/50 mix won't puke until around 265F.
 
turtlevette said:
Twin_Turbo said:
it controls the MINIMUM operating temp. .
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therefore it controls temperature. :D You're playing with words. We all know the STEADY STATE max operating temp is controlled by the system design parameters and ambient temperature.

But, you are making my point for me.

The point is, you have less control over temperature with no thermal reserve. You want fans pulling air past the radiator at all times to keep the coolant in the radiator as low as possible at all times so the engine thermostat will have more control over the maximum operating temperature.

Let me spell it out. I'll use an extreme example. If the electric fans kick off until the radiator coolant temp hits 185. Then the engine thermostat opens at 190 the delta T is only 5 degrees. You then immediately make a quick blast up a mountain road. What do you think the system temp is gonna do. Probably hit 230.

With the mechanical fan turning all the time the radiator coolant temp is lower say 140. The engine thermostat opens at 190 so the delta T is 50 degrees. Now you make the same quick blast up a mountain road. You have a lot of cooling capacity there due to the large mass of cool coolant in the radiator. The max temp probably will not exceed 190.

And at speed, who is going to argue that a negative pressure behind the radiator to increase the delta P resulting in more flow through the radiator is a bad thing.?

BTW, When i owned my Regal Grand National i bypassed the electric fan thermostat so it would run all the time when the key is on. Yea, the fan needed brushes much sooner than it would have but that's a small price to pay to keep engine temps from spiking.
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A factor that is being neglected is the flow of the coolant thru the radiator. It can be anywhere up to 30 gpm, depending on the pump used.
In a properly sized cooling system, the recovery time need not be long at all.
Remember that the capacity of the system is circulated several times per minute, thus removing a substantial amount of btu's.

A real life scenario.
My tow van had lost it's mechanical clutch (was spinning at about 2 rpm, useless), was stuck in traffic in S Florida in 95° temps and the temp gauge was past 3/4. As a last resort, I turned on the A/C (because I always install pusher elec fans for A/C only) and within 45 seconds my temp gauge had dropped to the normal 1/4 position. Turning the A/C on not only created air flow, but also increased the ambient temps to the radiator because of the condenser. A pusher is aproximately 50% as effective as a puller in a shroud.
Despite all this it is easy to see that an electric fan can be quite effective and certainly only needs to run when needed. The mountain scenario should work the same.

From posts I have seen, a lot of people that run electrics have not positioned their sensors correctly or have the temps set at inappropriate settings.

I favor mechanical fans with proper shrouds, except for A/C.

I have a 77 and a 75 C3, both have very clean cooling systems, both mechanical fans and a/c, both have the stock brass rads, both are auto trannies, both run Shaw tstats, neither have any of the underhood foam anywhere and both never run over 180° even in the hot S Florida temps whether at idle or at 3500 rpm on the road. In fact the 75 doesn't even have the chin spoiler, but it does have a Stewarts stage 2 pump. They are not, however high horsepower engines.
These temps were checked with a real pyrometer, so they should be fairly accurate.:)
 
I have no technicale data to share,but i have my experience with both setup's in my 78.
I just recently replaced the factory set up with a DeWitts alum rad with dual spals. The factory set up worked fine,no over heating issues at all,but alas the old rad sprang a leak this spring so i changed the whole thing out.
Now for the new setup,it also works great no complaints what soever.One thing i have noticed though,is that while driving at speeds say 55mph and over the temp gauge drops,quite a bit,to usually around 175*,the only times the fans have ever come on is while driving in town or setting at a light.
I never noticed the original set up drop like that at highway speed,it remained pretty much steady.
 
turtlevette said:
kwplot34 said:
the only times the fans have ever come on is while driving in town or setting at a light.
.
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how do you know when the fans are running?\
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I can here them come on,plus i can see the volt drop,and i lose about 100rpm when they kick on.
And before you ask how can you here them kick on while at highway speeds,I can't. But like i said earlier my temp actually drops at highway speed,and the temp gauge has to be at 195* before they will come on.
 
i think the old school style of a clutch fan is very simple and bulletproof. as long as your shroud is in good order and your car doesnt do high rev,s this is the simplest and best.....but if your looking to tidy up your engine bay, save some fuel and have a more controllable cooling system then electric fans are the way to go. its what i did. i have a manual switch so i can turn my fan on and off. thats the way i like it. i only have to do this if i ever sit at lights for a while. it sits on 185 most of the time . if it was a daily driver and i drove in built up traffic all the time i would opt for an automatic switch or the old clutch fan system but i dont .

IMG_0997.jpg

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Kid Vette said:
The CE article that I fell in love with states that a system with a 15 lb cap and 50/50 mix won't puke until around 265F.
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and actually puking saves the engine. When the coolant flashes to vapor a much larger amount of heat is removed from the surface.


Latent heat of vaporization.
 
Don't forget - the main reason to install an electric fan is so you have room for a spreader bar... :D
 
big2bird said:
mrvette said:
About a year ago I had a super RARE chance to run above 120 for some 8 miles, with a ~2 mile slo down in the middle to 80.....we topped about 150, it was hot FLORIDA summer at about 100f outdoors.....the car never had a problem
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I dunno Gene. The natural airflow at that sped and HP requirement of 40-80HP to cruise.
As Kid said, it's compression, but add in engine LOADING. Hard acceleration, uphill, in thin air. THAT"S a test. I can see a hill climb being the ultimate test, or a desert road course in high ambient.
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Well with ambient at 100f in my shaded back yard with some trees there, in the breeze without stewing in still air....I figger that street ambient off the pavement gotta be about 130-140f easy....freeway or city at a light....

at 150 mph for a minit or so, I would think that engine was about peaked out on temps....it didn't seem to bitch too much, didn't take to much of a trip down the off ramp and the fans DID turn on pretty quick....no question....

the off ramp here is totally fucked up with like a 1 MILE off ramp....into Orange Park off I 295 when you see the google you can find it....look for Blanding Blvd and I295 on a recent photo....funny to look at....longer than a dragstrip WITH shutdown lanes....

at any rate my silly single row rad worked barely adequately with the '87 vette fan in the stock '72 shroud....and it was sealed up pretty damn good too....better than stock anyway...

but with my Spals setup I was determined to seal it tighter than whale pussy, and that's WATERPROOF.....and it cured my tendency to run hot a idle in the traffic just off the freeway....

I say 100f temps here tend to thin our the air pretty good too....not as much as 7500' elevation maybe...but then I not making the POWER at 7500' as at sea level course I am NA ....

but since then I have not done a full power run, with the up and over air cleaner assy...there is lotsa wind openings in there that miss the rad core....

so far, its marginal affect.....but with GAS at 4.20/gallon for premium 92 I don't tend to driver the vette a whole lot, DAMNIT....so I really can't swear if the car overheads at high speeds or not, currently....

80-100 is NOT a high speed run,...IMO.....

120+ is....
 
turtlevette said:
I guess i'm willing to accept electric fans but i won't go to the trouble to convert.

My philosophy is run them all the time. Any time the key is on.

None of you guys run your cars for more than 30 minutes at a time or more than a few hundred hours a year anyway.
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BULLSHIT LITTLE EVA.....I run the socks off my car whenever I can....

go to the beach quite often...top down most of the time, but a/c on and top UP for the midday trip home.....beach is some 45 miles one way through mainly cityish traffic....no runs at 70 even.....

much less my runs across town to see some buddies once in a while....

sorta depressing with gas to high....50 miles would put TT into Italy allready....:pprrtt::hi:
 
Bullshark said:
Kid, Now I remember....back then you dealer mechanics said if it's not pegged over in the red ....not a problem. BB are supposed to run hot! :lol:

Bullshark
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:bounce::bounce::smash:

Ya know summfin?? U rite!!, I remember them saying that.....didn't think it was applied THAT way though....

the meaning HOT CAR was applied either of TWO differant ways back when....

stolen or very fast....

which come think of it....could be the same thing under certain circumstances....:bump::surrender:
 
Z-man said:
Don't forget - the main reason to install an electric fan is so you have room for a spreader bar... :D
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It may be a good reason on a BB; however I'm guessing that most guys that install electric fans don't know what a spreader bar is. :tomato:
 
turtlevette said:
mrvette said:
turtlevette said:
BULLSHIT LITTLE EVA.....I run the socks off my car whenever I can....
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how many miles you put on it in a year?
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10k/year minimum....wear out a set of tires in 4-5 years....but damn nearly NO burnouts....I do corner quickly though....275-255/50/17

course at 5 bux/gallon, I suspect my thoughts of making an electric car maybe a thing I have to do....wanting a Fiero or Saturn coupe for the test....I think an old Saturn would do nicely.....

another post...OT section....engineers welcome....

:stirpot::stirpot::stirpot:
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MYBAD79 said:
big2bird said:
Huh?
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So are there any cars with belt driven fans manufactured after 1990 ??

I'm not saying the stock system is all that bad but if electric fans were not better then why is everybody using them ? Like I said, I don't have a cooling problem but if I did I'd rather spend the money on a electric fan setup than on a new fan/clutch/seals a.s.o.
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Perhaps for the same reason you didn't see too many low spec cars at one time fitted out with electric windows, a/c, power steering etc etc as a standard items until the manufacturers (usually far eastern) of such components improved quality and performance and were able to reduce the supply prices because of the huge volumnes being sold.
 
I tried to read all 10 pages of this post in my limited time (my car is calling). What I can tell you is, I have a very hot blooded LS5 in a 69 coupe. Somebody did a pretty good swap with it too. When I bought it, the damn thing would run for 30 mins. and just about overheat. It would be just a thin hair over the 210 mark, and not come back down. I started in on this problem, and won't bore you with ALL the crap and 7 radiators I went thru..........
I lastly and finally installed a DeWitt's aluminum radiator that fit the small block core support. I installed a Lincoln Mark VIII 2 speed fan with 2 constant duty solenoids and I don't have an overheating problem any more. To me, that's a feat in itself, living in the Tucson, AZ desert with common summertime temps well over 100* for many days in a row. I wired the solenoids to handle the amp spikes on fan start up, which is low speed upon starting the engine. The other for high, is triggered by the temp sensor in the head, or A/C turn on. Whatever I did wrong, isn't showing up with over a year on the car, OK, a few hundred miles then.
I'm a firm beleiver in DeWitt's radiator, and a good Mark VIII fan wired properly, that's about all I can say about electric fans.

BBTank
 
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