Electric Fans - Who Needs 'Em>

[Kid Vette]

Since a few people have shared anecdotal experience to back up their claims for electric fans, I'll share my own experience with a clutch/fan setup. I have a 350 ci, .040 over, 9.5:1 compression, cast iron heads, manual trans, no AC, 180 thermostat. I have the water pump as underdriven as possible - PN 3770245 water pump pulley with a PN 3858533 crank pulley - the old Z-28 setup with a 5 blade fan. I have a DeWitt's Direct Fit aluminum radiator with new seals. And one other thing I should mention; there's NO chin spoiler.

With this setup, after the thermostat opens the temp gage NEVER moves. Doesn't matter how hot the weather, stop & go city driving or high speed - it NEVER moves. I know everybody is going to jump in and point out that I don't have a big block, auto trans, AC or something else that would tax the cooling system more. I would agree however the fact that the gage never moves indicates that I have excess cooling capacity as is; so if I went to a BB or something else I would still have that excess cooling to fall back on plus, if I needed it, I could go to a 7 blade fan, different pulleys or install the chin spoiler to give me even more cooling.

And with this setup I can run my el cheapo $20 AutoZone alternator and don't have to worry about all the switches, sensors, relays, wiring, fan motors, etc to burn out or fail. KISS!

 

[Twin_Turbo]

1. Why would you ever want the coolant in the rad to heat?

The cooland cools in the rad, it doesn't heat. What do you mean? Are you saying that without the fans the coolant will heat up in the rad? Without the fans the coolant temp will reach a "momentarily" steady state equillibrium determined by the temeprature of teh coolant, it's flow speed, the outside air temp, pressure (and moisture) and the air velocity through the core. Change any of the variables and the coolant temp goes either up or down.

As I said, I don't give a rats ass what the temp in the radiator is. It's the cylinder head temp that matters.

2. My car is well enough maintained to drive 600 miles to a track, run the car all day on the track and drive 600 miles home the next day.

Ok, but you yourself said you had warped the heads from not fixing a pinhole. How many times have you actually been on the track? My car NEVEr broke down because of overheating. It boiled once because a hose clamp had chaved through heater hose, that's all.

3. Broken or not. That tiny spoiler is not enough to force enough air up and into the rad to the point of self cooling. Anyone with electric fans could just pull the fuse and do a test.

It will if you are driving at a normal speed, not stop & go. The fans on my never came on unless I was going real slow. If you constantly have to rely on the fan for cooling you have other issues. That tiny spoiler will have a huge impact on airflow, HUGE!

4. Almost all C3 owners are lying bastards and say their cars don't overheat. A blast up the mountain from Denver to Frisco and a guys perfectly restored 72 LT1 was puking antifreeze all over the hotel parking lot. Right before we left Denver he said his car NEVER overheated. It may be the case that 99% of c3 owners do not push their car hard enough to see cooling problems. Running through the gears once is not enough to do it.

5. I did think about the possibility that at idle electric fans will move more air than a mechanical fan. That may be one advantage. But why switch them off and let the system heat up. That's stupid. The problem is that the electric motors are only rated for a limited number of hours before they quit. The brushes go.

Why not switch them off? You are saying hot coolant is bad coolant. in fact 190 deg coolant is bad coolant. Above 200 and the engine will run better, cleaner. The only reason you can't run higher temps is because of hot spotting and detonation. It would be a real win if you could run the coolant much hotter.

6. I would expect that you have parts rusting out on your car after sitting so long. I used to work in the Nuclear PP industry. Because it took 10 years or longer to build the things we were replacing parts that were never used 1 day due to rust and non use. Systems were outdated before the plant ever got on-line.

7. How many hours of seat time or miles did you actually drive your car before it was wrecked? Just curious. What do you use for a daily driver? The old truck?

Yes, the frame on my car rusts, so what..it's just surface rust. The suspension parts rust also, all bare steel. No big deal. For the rest, there isn't much that will rust, most of it is aluminium.

I don't know how many miles I drove my car, 20 30K..no idea. It wasn't wrecked, it was a fender bender/rear collision. Just cosmetic damage.
I drove it for 3 years after building it up initially.

I drive a coupe fiat as a dd. That "old" truck isn't an old truck, it's in pristine shape, no rust anywhere, full custom leather uphostery and new/rebuilt from the ground up. It's just another toy. Since I refuse to drive on propane I hate to drive that car on a daily bases with gas being $11 a gallon here.

As for pushing the car, I'm willing to bet I have driven my C3 faster than most anyone here. I've had it flat out on the autobahn on more than occasion. That's WOT for at least a couple of minutes, have you ever done that?

 

[mrvette]

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, and I have a stock a/c cond, and a ATF cooler in front of the late camaro single 1.25 inch thick row plastic tank radiator....:

Gene, 8 miles at that speed is less than 4 minutes of heating the system. With the 2 mile slow down you were only stressing the system for 90 seconds at a time. Try it again for longer next time.

my rad is 2 rows of 1.25, twice as big as yours.

Yeh, but it's hot it's HOT, don't take all that long enough running speeds here in Florida to take up the heat fast....especially when stopped at a traffic light right off the freeway....where streets temps gotta be 130++ easy in traffic and bright sunlight I would have bought a 2 row rad also, but at the time I didn't have a source for it.....much less know the core size to as to match my support....next time around....

 

[big2bird]

Interesting discussion.
We have effeciency of the two to consider, we have reliability to consider, and advantages.
As for reliability, I think the mech has some reliability advantages.
Mech fan has fewer parts. A broken belt will take down either system, as you would lose the pump with either system, let alone the alt function also.:smash:
With the electric, I can see where stop and go with A/C on and high ambient temps, you would get more air flow at idle/slow speeds. I can also see the requirement for a HO alt here.
So, I guess the arguement boils down to effeciency, and without comparing apples to apples in a controlled environment, would be hard to settle.
Anybody agree or disagree with these comments?

 

[mrvette]

NO, no disagreement on that particularly, except for on these sharks, that damn shroud and all that fan in the way botching up room for other crap, I can't see keeping it, mechanical or electric.....the Rad blew on my car when I got it, within a month or two....so that meant I had to get another rad, and then went to serp drive, reverse rotation pump, so mechanical fan went, I had a '87 vette electric fan from an old tear out so put that on the shroud kinda like what TT showed above....it worked ok for years, but allways marginal here in the heat....so I decided to do the Spals, and it's been fine since, even with that welded up LT1 mani on the L98 heads and the consequencial 'limited' water flow....but in fact the pipes are 5/8 ID on each side, plus the steam? flow/water pipes in the rear leading into the pump suck heater return line....

All I know is when totally hot, and in traffic the fans take that temp down like a dropping stone, and so well, good enuff....

:search:

 

[Bullshark]

Bird, reliability as I am sure you know, is a system thing. Just addressing the mechanical mechanisms reliability does not take into account the reliability of the over all propulsion system when you factor in the performance of the mechanical fan subsystem. In other words, the temp spikes due to looser temp control capability take a toll on the system. radiator, head gaskets, etc. etc.

Bullshark

 

[big2bird]

The frontal area, the radiator gets air from underneath. The biggest problem is not the frontal area, it's the sloped radiator. That's why the seals are so important, missing seals resutl in air flow not going through the core but past it and over it.

Good point.
In the building A/C industry the last 20 years, the engineers have added turning vanes inside ducts to increase effeciency/reduce turbulence when going around corners. I have always wondered if a bank of light weight alum. turning vanes placed ahead of the radiator to redirect the airflow straight into the core would solve this.:fishing:

 

[big2bird]

Bird, reliability as I am sure you know, is a system thing. Just addressing the mechanical mechanisms reliability does not take into account the reliability of the over all propulsion system when you factor in the performance of the mechanical fan subsystem. In other words, the temp spikes due to looser temp control capability take a toll on the system. radiator, head gaskets, etc. etc.

Bullshark

Point well taken. There ARE documented advantages in modulation control as in chiller/central plant systems.(Or nuclear power plants):stirpot:

 

[Kid Vette]

:withstupid: And Bullshark, you may (I'm still not convinced) be one of those very rare instances that truely requires electric fans - 502ci, AC, not sure if you have an automatic or not. But these cars came from the factory with 427s with 11:1 compression, and loaded with all the options and, with the exception of the L-88 (12:1 compression ratio, no radiator shroud), didn't overheat. Not too many Vettes running around now with that kind of compression today. And compression is one of the main contributors of engine heat (not lumpy cams as some would have you believe).

 

[big2bird]

But these cars came from the factory with 427s with 11:1 compression, and loaded with all the options and, with the exception of the L-88 (12:1 compression ratio, no radiator shroud), didn't overheat.

Sorry Mark.I don't quite remember it that way.:smash:

 

[big2bird]

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

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.

 

[Bullshark]

But these cars came from the factory with 427s with 11:1 compression, and loaded with all the options and, with the exception of the L-88 (12:1 compression ratio, no radiator shroud), didn't overheat.

Sorry Mark.I don't quite remember it that way.:smash:

Ditto here Mark. As a matter of fact, My Blue Angel 69-427 vert has the original cooling system still in place. The engine was an original 427-390hp which was souped up with high compression L-88 pistons, Fireball L-88 like cam and reworked original iron heads. The A/C is not installed at this time and I upgraded the water pump to a higher volume aluminum style. It has a 4:11 rear diff so you can imagine the rpm it is running down the highway. I watch the temp gage like a hawk Enough said.

Bullshark

 

[Kid Vette]

Ditto here Mark. As a matter of fact, My Blue Angel 69-427 vert has the original cooling system still in place. The engine was an original 427-390hp which was souped up with high compression L-88 pistons, Fireball L-88 like cam and reworked original iron heads. The A/C is not installed at this time and I upgraded the water pump to a higher volume aluminum style. It has a 4:11 rear diff so you can imagine the rpm it is running down the highway. I watch the temp gage like a hawk Enough said.

Bullshark

Yeah, 12:1 compression may warrant some extraordinary measures. I'm guessing guys running that kind of compression comprise less than 5% of those spending the big bucks on electric fans. You say you have the original cooling system in place; I assume the radiator has been replaced?

I worked as a line mechanic at a Chevy dealership in the early 70s. Vettes were still equipped with 454s at that time, AC was a very popular option by then and all the smog stuff was creating even higher underhood temps. NEVER had a Vette come in with overheating issues. However. . . we were swapping out Vega engines due to warped heads and scored cylinders on a weekly basis. :smash:

 

[Twin_Turbo]

The frontal area, the radiator gets air from underneath. The biggest problem is not the frontal area, it's the sloped radiator. That's why the seals are so important, missing seals resutl in air flow not going through the core but past it and over it.

Good point.
In the building A/C industry the last 20 years, the engineers have added turning vanes inside ducts to increase effeciency/reduce turbulence when going around corners. I have always wondered if a bank of light weight alum. turning vanes placed ahead of the radiator to redirect the airflow straight into the core would solve this.:fishing:

There's only 1 little problem, you won't be able to open thood. so unless you have a flip front or a drop on hood you have a problem there, the little vane I added to X's car is as large as it can get without interfering with the hood.

 

[Bullshark]

Yeah, 12:1 compression may warrant some extraordinary measures. I'm guessing guys running that kind of compression comprise less than 5% of those spending the big bucks on electric fans. You say you have the original cooling system in place; I assume the radiator has been replaced?

I worked as a line mechanic at a Chevy dealership in the early 70s. Vettes were still equipped with 454s at that time, AC was a very popular option by then and the all the smog stuff was creating even higher underhood temps. NEVER had a Vette come in with overheating issues. However. . . we were swapping out Vega engines due to warped heads and scored cylinders on a weekly basis. :smash:

No, still the original radiator, but it has been cleaned out and refreshed a couple of times. all rods are still in tact. I'm not exactly sure of the compression but 12:1 is probably close with those 100cc closed chamber iron heads and domed TRW pistons! "NEVER had a (BB) Vette come in with overheating issues"?? Did you live in Canada?
BTW 70 BB's didn't have smog pumps. About the only thing was a TCS solenoid.

Bullshark

 

[Kid Vette]

No, still the original radiator, but it has been cleaned out and refreshed a couple of times. all rods are still in tact. I'm not exactly sure of the compression but 12:1 is probably close with those 100cc closed chamber iron heads and domed TRW pistons! "NEVER had a (BB) Vette come in with overheating issues"?? Did you live in Canada? BTW 70 BB's didn't have smog pumps. About the only thing was a TCS solenoid.

Bullshark

I bet an new aluminum radiator would make a huge difference. They can only clean them so good.

I did my wrenching in northern Indiana from 72-76. Summer temps in the upper 90s are not unusual. We were dealing with the extreme lean mixtures that were being used at that time to bring emissions down. Chronic issues were pinging under acceleration and dieseling after shutoff. Lean mixtures=hot engine. Believe me, if they were having overheating problems when their vette was still on warranty; they would not have hesitated to bring it in for service!

 

[Bullshark]

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

 

[BRUTAL64]

Yes sir. She's got Vortec heads, serp set-up, and a CS alternator(Only 1 though). "Marine cam NOT included."

I apologise. I couldn't help myself.:smash::smash::smash:

Unless the CS is properly clocked by the O'Reily experts it won't work... well it might or might not.... get I clocked or better get it replaced, return it or buy another one.... whatever makes you happy .... life is tough....

O'Reily experts???? Is there such a thing?

 

[MYBAD79]

O'Reily experts???? Is there such a thing?

yes, here's one:

[/QUOTE]

 

[turtlevette]

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.