electric fans

[yakatak76]

so has anyone thought about pulling the fan off, pulling the factory fan shroud out, and installing an aftermarket electric fan to cool off the savage beast under the hood?

unless of course you are going for ncrs standards that is.....

 

[1979toy]

I'm using the model 210 Flex-a-Lite, it fits like it came that way from the factory. Others have used late model Camaro fans or Spal fans.

 

[JohnZ]

Why remove the factory system that was engineered and developed to cool the beast to begin with? Nothing works better than the original factory system for all-around cooling effectiveness if you keep the components working properly. Only two things determine cooling effectiveness - radiator heat rejection capability and airflow through it, and the factory system was designed to optimize both of those factors. As soon as you start to dismember the elements of that system, you create new problems and start having to throw band-aids at it to try and make up for the lost efficiency. If you add more motor (thus more heat), just add more radiator.

 

[Bob Chadwick]

John,

I've read your various posts about electric fans with interest. You are one of only a few that do not speak of electric fans as the saving grace on the C3's.

My stock fan keeps the car cool at speed and within limits at idle in traffic even on the hottest of days. (up to about 220)

My problem is the a/c. It blows very cold at speed but stuck in traffic the temperature creeps up about 20 degrees or so. About the only solution I have read about is replacing the stock fan with an electric fan that will blow a high volume of air across the a/c components at idle.

What are your thoughts on this?

Bob

 

[JohnZ]

Bob, having been involved in design and development of Chevrolet cooling systems in the late 60's-early 70's, I'm pretty familiar with their capabiities and behavior. Assuming there's room for it, a thermally-clutched 7-blade stock fan with the correct shroud and seals in place will ALWAYS move more air than any electric fan; not only will it move more CFM of air, but with the proper shrouding, it draws air over the entire surface of the core. Electric aftermarket fans only draw air over the (relatively) small surface of the core immediately ahead of the circle described by the electric fan blade, leaving virtually no airflow at all through 50% or more of the total core surface.

Corvette cooling systems didn't have a lot of "margin", but they met all the idle-hot-soak shed tests that all Chevrolet products had to meet, with new parts. Nobody ever expected an OEM radiator to maintain its heat rejection capability for more than ten years, and most older Corvettes have built up enough scale and corrosion (which becomes an insulator to the passage of heat from the coolant to the air) on the tubes in the radiator that the actual heat rejection capability of the radiator is reduced by 30%-50%; this becomes a "beyond-margin" situation in traffic with the A/C on. If the radiator is sized correctly and has comparable tube surface area to the original, it will cool the car, but most folks don't want to "bite the bullet" and replace the scale-coated old radiator with a new one that will restore the original heat rejection capability, or they replace the old radiator with one that "looks about the same" and "was a good deal" - these replacements seldom are as efficient as the original.

 

[Bob Chadwick]

Thanks John. While I may ultimately have some deficiencies in the radiator's abilities, the problem I want to resolve at this point is low speed air flow. I will take a closer look at the air flow of my system later this Spring. The shroud is in place and in good shape, as is the spoiler. I will take a look at the seals and fan clutch to see if there is something there. I'm assuming that the 7 balde fan that you are talking about is stock as I have seen ads for after market fans with larger and more blades.

By the way, I really like your car.

Thanks for the help.

Bob

 

[Don&Kelly]

I removed the schroud & added two 12" electric fans & they cool my C3 much better than the old fan did ...

 

[yakatak76]

thank you john z for your thoughts. since now i know a little bit about your history, why not a two piece shroud for ease in removing it in order to work on the front part of the engine. i had a 79 blazer that had a two piece shroud which made it much easier to remove.

thanks

 

[SwaveDave]

The reason electric f ans are gaining in popularity , is because, many people have an engine buildup increasing hp/tq and often compression. This all adds to the heat of rejection from the motor which the cooling system and oil has to handle.

The guy before me, replaced the radiator and mech. fan with a 4 core radiator and the twin-fan package from an early 1990's LT 1 Vette (includes shroud for each fan and an entire perimeter enclosure which is almost the same size as the radiator) . This set up moves a hellacious amount of air thru the radiator and i can maintain 180 f. degrees head temp. at idle, in 90 degree ambients. Pulls 22 amps and i have it work off of a Remote Bulb Controller with the bulb in the passenger Head.

The key to any cooling system efficiency are some fundamentals : Make sure the radiator is sealed up good around the sides/same with the a-c condensor, make sure the top radiator seal fits tight against the hood when it closes, run a 180 degree stat , power wash the radiator / condensor /fan blade , dont use any more than 25% coolant to distilled water ratio, use a bottle of Water Wetter, makes sure the inside of the cooling system is clean , make sure your lower radiator hose isnt collapsing at higher rpms, make sure y our water pump is up to the task, pop open the headlights on very hot days to allow more air to come in to the radiator/condensor , and install a heater shutoff valve in the heater inlet hose so no (hot) water enters the dash.

Dave

 

[pws69]

Bob, having been involved in design and development of Chevrolet cooling systems in the late 60's-early 70's, I'm pretty familiar with their capabiities and behavior. Assuming there's room for it, a thermally-clutched 7-blade stock fan with the correct shroud and seals in place will ALWAYS move more air than any electric fan; not only will it move more CFM of air, but with the proper shrouding, it draws air over the entire surface of the core. Electric aftermarket fans only draw air over the (relatively) small surface of the core immediately ahead of the circle described by the electric fan blade, leaving virtually no airflow at all through 50% or more of the total core surface.

Corvette cooling systems didn't have a lot of "margin", but they met all the idle-hot-soak shed tests that all Chevrolet products had to meet, with new parts. Nobody ever expected an OEM radiator to maintain its heat rejection capability for more than ten years, and most older Corvettes have built up enough scale and corrosion (which becomes an insulator to the passage of heat from the coolant to the air) on the tubes in the radiator that the actual heat rejection capability of the radiator is reduced by 30%-50%; this becomes a "beyond-margin" situation in traffic with the A/C on. If the radiator is sized correctly and has comparable tube surface area to the original, it will cool the car, but most folks don't want to "bite the bullet" and replace the scale-coated old radiator with a new one that will restore the original heat rejection capability, or they replace the old radiator with one that "looks about the same" and "was a good deal" - these replacements seldom are as efficient as the original.

So YOU'RE the one.....

 

[page62]

Interestingly, the '79 L82 with A/C came with an auxiliary electric fan behind the radiator. It is designed to come on at 232 degrees(!) or whenever the A/C is on.

When I first bought my car, the fan clutch was bad. I believe the car was being cooled solely by the electric fan. The temp would rise and then abruptly cool off -- so it must be effective...

One final comment: Before I installed an OD tranny, the car would run very hot at freeway speeds -- 220+ degrees. Installing the new tranny dropped freeway rpms by a third, and engine temps are down 20+ degrees!

 

[LEEJANDZ]

page62 --- Interestingly, the '79 L82 with A/C came with an auxiliary electric fan behind the radiator. It is designed to come on at 232 degrees(!) or whenever the A/C is on

I didnt get one of those on my 79 L-82.

 

[page62]

Do you have A/C? If so, it should be there. It's even shown in the Assembly Manual.

 

[LEEJANDZ]

page 62 --- Do you have A/C? If so, it should be there. It's even shown in the Assembly Manual.

A/C originally came with the car but one of the PO took out most of the components. Instead of having the beautiful interior piece that surrounds the shifter with the A/C controls, window switches, etc... I got a B&M sport shifter and some tacky black carpet. Ugly Ugly Ugly

No top flight award for me I guess

JASON *** I SELL MAGNECOR IGNITION WIRES!!!

1979 L-82 - BLACK/BLACK - T-TOPS - B&M AUTO

*UNDER CONSTRUCTION*
POLYURETHANE FRONT END - EXHAUST

 

[JohnZ]

Most FACTORY electric fan setups include a shroud that encloses the entire surface of the core, so the entire core surface is exposed to airflow, and most have rubber "flappers" that open up at highway speed to allow additional ram airflow.

The least-efficient electric fans are the usual aftermarket variety that you attach directly to the back of the radiator and have no shroud - just the round fan frame - these are the ones that only pull air through the circle described by the fan blades.

The factory-engineered electric fan setups are pretty efficient; the aftermarket ones with no shroud are not.

 

[sscam69]

The dual 11" becool (spal) fans woud fall under the "efficient" catagory?

I think I know which ones you are talking about JohnZ, the Spal fans have a shroud as part of the assembly and have little rubber flaps that run along the top and along the bottom of the shroud. Though I didn't know they were for high speed airflow.

I have have uploaded a pic

 

[yakatak76]

sscam69,

man look at all that room in there. i bet you don't have to take the front sway bar off and since you have the shroud out of there you don't have to take that off just to remove and replace the lower radiator hose. thanks for the picture.

 

[Don&Kelly]

sscam69


Thanks for the picture - those are the fans I have & they work very well.

 

[Bob Chadwick]

Most FACTORY electric fan setups include a shroud that encloses the entire surface of the core, so the entire core surface is exposed to airflow, and most have rubber "flappers" that open up at highway speed to allow additional ram airflow...The factory-engineered electric fan setups are pretty efficient; the aftermarket ones with no shroud are not.

Isn't there also an issue with the direction that the electric fans point also? The stock fan, in addition to creating air flow over the radiator, creates air flow moving air over the engine. The electric fans that attach to the radiator point downward and blow the air under the car and don't create the air flow over the engine.

 

[sscam69]

man look at all that room in there. i bet you don't have to take the front sway bar off and since you have the shroud out of there you don't have to take that off just to remove and replace the lower radiator hose

Yeah there is definitely a lot of roon now!

Replacing the hoses is a breeze. According to Be Cool I was suppose to use a 76 or earlier upper radiator hose. Didn't work, would crimp when I tried installing it. Thats the reason for the aftermarket hose. I matched the lower one for looks.

The only problem I had was having to install the radiator and fans seperately. When I first tried to install it I thought I had enough room to install the radiator with the fans attached, but didnt. So I just installed them seperatly.

I agree with JohnZ, that the stock cooling system should suffice for a stock configuration as long as everything is up to par. BUT I have bigger plans for either a 502 crate or a Vortech supercharged 400c.i. SBC. I decided to bite the bullit early.