toobroketoretire

When it comes to cooling systems your C3 came from the factory with a very reliable system. When changing over to electric fans BIG problems often occur and its because of inadequate air flow thru the radiator core at idle or at freeway speeds. I'll rate them according to their efficiency:

1. The very best is the OEM tapered fan shroud with a 20" opening (314 square inches) and 18" 7-blade severe duty clutch fan spinning all the time.

2. The next best is the OEM tapered shroud with a 20" opening (314 square inches) but using an 18" electric fan running all the time at idle speeds.

3. The next best is a flat fan shroud with a 20" opening (314 square inches) and 18" electric fan running all the time at idle speeds.

4. The next best is a flat fan shroud with two 12" openings (only 226 square inches) and two 11" electric fans running all the time at idle speeds.

5. The next best is NO shroud (486 square inches) and two little 11" electric fans running all the time at idle speeds. This setup will work okay at freeway speeds because of no air flow restriction thru the radiator core but won't work worth a darn at idle speeds because of no shrouding.

6. The very worst of all is NO fan shroud (486 square inches) and two little 11" electric running part of the time at idle speeds. This setup will also work okay at freeway speeds because of no air flow restriction thru the radiator core but won't work worth a darn at idle speeds because of no shrouding.

Electric fans may provide adequate cooling at idling speeds because the amount of horsepower (heat) being developed at idle speeds is next to nothing; maybe 5-6 horsepower and that ain't much. But when the car is traveling at freeway speeds a pair of 12" openings only allows about 66% of the air flow thru the core that an OEM 20" shroud allows and that's why engines with little 11" electric fans usually overheat at cruising speeds. I recommend only using the larger 18" electric fan when making the change and set it to start running at about 200 to 205 degrees.

speedreed8

running dual spals 11", i have none of the problems you mention at freeway or at idle.

TheycallmeDave

Ive got twin fans in shroud off of an early 90's vette and they move a helacious amount of air . Never overheated---- not even on a 100 f day with a/c on. They free up some hp too.

gmachinz

I don't know where this thread is coming from-I run OEM electric fans in about everything with none of those issues either. Aftermarket fans in general tho-suck....and not efficiently either.

COOLTED

I had an electric on my Trans-Am. it ran a little warm, but it I will admit it was too small for my application. But I never really had any problem with it.

Sigforty

Area is only part of the equation. You also have to account for air velocity. The smaller areas would have increased air velocity.

Additionally, the better shrouds for electric fans have bypass flaps that allow high velocity air at cruising speeds to open and move the air out. With this method you have a variable area of fan shroud.

Kacyc3

E-fans should not have to run while going down the interstate, if they do there is another problem they are covering up.

MrForce

OEM fans in OEM shrouds will usually outperform anything else. Chinese aftermarket junk is, well, Chinese aftermarket junk.

pws69

It's coming from someone who knows absolutely nothing about what he is talking about!!

Kevin68

And at idle electric fans are running full speed while the belt driven fan turns slower. So even though there is less area, an electric can move more air.

DUB

What amazes me is that on most hot days....electric cooling fans are not ON when the Corvettes I work on are being driven. The fans will generally come on when the car is allowed to IDLE for a long time. Working on the 1984- later Corvettes. The fans generally do not come on until the coolant reaches 226-228 F. And unless there is a coolant system problem...I have rarely seen the electric cooling fans come on when driving it. And I do not consider 'stop and go'---'grid lock traffic' as driving it.

All of the foam seals to seal off the radiator and hood make difference along with the from air dam or spoiler....especially when it is being driven...obviously. Regardless if it is a factory or aftermarket set-up.

But rating which system is BEST to WORST...it kinda one persons opinion.

The only statement that I can agree with is:

I have installed cooling systems back to factory specs...and also using aftermarket parts and do not have a problem with either working correctly...IF ...all variables are taken into consideration. So being able to definitively state that one system is better than the other.....is just not possible....in my opinion...when the subject matter is strictly its cooling capabilities.

DUB

bluegtp

I've never had an issue with my dual little ford focus fans. Never had issues with the new radiator and electric fans in 95-100 degree weather in traffic or on interstate with th350 trans and 3.55s outback (usually 3000 rpms at 60mph). If you're having issues with electric fans check and double check all of your seals are in place around the radiator and verify you radiator doesn't have corrosion built up like mine did.

30+ years worth of junk:


And the dewitts. ......

mrvette

BTDT, OP dunno jack what he talking about.....

a PROPERLY shrouded/installed Dual Spal fan setup cools my 362 cit FI automatic '72 with no problems, In FLORIDA and this last summer has been a BITCH!!! and too boot I have a go to hell engine oil cooler between my 1.25"? single row aluminum rad from a ~89 F body and that cooler is for the trans, that runs at ~130f.......someone needs learn how to install FANS.....

and YES, I have had many a fan install in this car over some 20 years now, finally settled on the one that WORKS!!!!!

rcread

There is a rumor that his next thread is titled "Why overdrive transmissions cause such a reduction in mpg".

Les

Shark Racer

Can we add a "condemn" feature to the forum, or some other kind of anti-thank?

I love my electric fans. The car has ran impeccably with them, and as long as the car is basically MOVING they never come on. They come on when stuck at idle for a few minutes and shut off after a few minutes. I actually disconnected one of them during a smog test and the single fan was more than enough to cool the engine.

Bad Bird

Why do you keep starting these stupid threads?

SH-60B

I agree, I have dual e-fans with aluminum radiator, cools much better than the factory set-up, never gets above 195* anymore. This thread's a joke.

Big2Bird

A radiator does not know what is providing the air flow.
I find it interesting that the OP has listed the efficiency of fans without a single word about CFM.
If a stock fan with a shroud provides "X" CFM, and an electric fan with shroud provides "X" CFM, there is no difference, except the electric unit would use less HP, and provide more "at idle" air flow for air conditioned vehicles.
Above 35 MPH or so, it just doesn't matter. The air is forced thru the radiator faster than a fan can provide.

REELAV8R

Someone gets really bored easily. Posts just to inflame. Maybe they didn't teach physics or chemistry where the OP went to school.