Run electric fans all the time?

AJ/FormS said
I'll try to be as nice as I know how, about this;
I'm guessing you have no idea how alternators work. Electric fans are not zero energy devices.
I know nothing about electric fans, just like I know nothing about a lotta things, and I freely admit it. I have heard that the better fans draw 40 amps, so if that is true, then; at 40amps x13.5volts, they suck 540 watts or .724 horsepower net. But alternators are only maybe 10 to 20% efficient so really, .724/.15=4.83hp gross. If you have 2 of them, that's 9.65hp. And how much does the controller burn up? This energy has to come from somewhere, and the alternator is it.

But wait it gets better, In traffic at sub 30 mph, your fans could be both on, sucking all that 9.65hp from your monster engine, now idling along at the same 25hp, everybody else is moving at. Ok so 9.65/25=39.6% of your crank power is going to driving the fans. Gee that's 3.168 cylinders worth...... over 3 cylinders. So, you don't notice it cuz you just open your throttle a lil more. But it shows up at the pumps, all the same.

So what's the advantage to electric fans?
On the street for a street-only type car,cooling wise, there is no advantage.
At the track, being able to set them on max, in the pits, yeah, that could be an advantage.But my all steel, 7-blade, hi-attack angle, thermostatically controlled clutch-fan, keeps my engine at a constant 207*F no matter the circumstances, so...... no advantage to me.

After 35/40mph, for a streeter, neither fan even needs to be there, cuz ram-air is, has been, and will continue to be, the primary cooling force, pushing air thru the rad, rather than pulling.
Try to think of it this way; After 35/40 mph, my mechanical fan is in danger of being a restriction to cooling. But if I drive a lil faster the air pressure coming in could start to power my fan into generating power, just like a wind-turbine. Can your electric fans do that trick? lol. Well, no, um, they're not connected to the crank, and um, they're not even on. Think about it. The Earth is not a sphere. think about it.

First, as goldduster318 pointed out, your math is totally wrong. Max draw on the Contour fans is ~40A but that's at only at start up and that lasts a second. That's both fans at high speed and then it drops to 20-25 amps. That's what the alternator would "see". Low speed is less draw than that, and 99% of the time my fans are running at low speed. So ~15 amps. There are dyno tests out there showing losses due to alternators, the highest one I've seen was like 1.5 hp. Most mechanical fans will triple that loss on their best day for their minimum loss, not their max.

And seriously, who cares about the hp loss at idle? You're not doing anything at idle. You're making more horsepower than you need because you're not going very fast and the engine's baseline hp is going to do everything you need. What matters is the power loss at higher rpms. And at higher rpms the electric fans are off because you're moving. A mechanical fan is still spinning, stealing MORE horsepower than at idle, because even with a clutch it's spinning at 30% or better of the engine RPM when it doesn't need to be moving any air at all.

This is really a no brainer. An electric fan moves the most air when you need the most air flow (idle and low speed), and steals no power at all at speed when you need the power because it will be OFF. A mechanical fan moves the least amount of air when you need air flow the most (idle and low speed) and will steal the most amount of power at higher rpms when you might actually need that power, because you can't ever shut them off. No one races at idle. Heck no one drives at idle. The electric fan drawing power at low rpms is fine, because at low rpms you're not doing anything that needs that power. The mechanical fan steals more hp the faster the engine spins. That's exactly when it matters.

famous bob said
Gotta say , my engine makes a hell of a bunch of heat at idle ------------

Well, it makes less heat at idle than at redline. But it also dissipates the least amount of heat at idle because there's no air movement. I think that's what he was getting at, the air flow at idle is more important than the water flow from the pump. But again, the problem is if you overdrive the pulley to spin the fan faster at idle you may spin the pump too fast at higher RPM's. Another issue electric fans avoid, because they spin whatever speed they're rated at no matter what the engine rpm's are. So you can drive the water pump the way it needs to be driven and not worry about that screwing up the fan speed.

DrCharles said
I've been looking for help on Moparts and the consensus seemed to be that the shroud on the Contour fans is too obstructive. So I removed the fans entirely for a test.

Warmed it up a bit to 160 on the gauge, started driving, temp went to 183 and t-stat opened as expected. Fast drop to 165 as the cold coolant in the radiator hit the engine, then gradually back up to 182. I drove a couple of miles at 30 mph and it stayed on 183.

So I turned around in the driveway (10 sec. max) and while I was doing that, the temp popped up to 190. Started down the road at 30 mph again... and it would not come down below 188 in the next mile.

Made another 3-pt turn down the road, and during that pause of maybe 20 seconds, it rose to 198. Another mile, would not come down below 196, so I drove back to the garage and shut it down! Went up to around 215 due to accumulated engine heat. I put the garage fan on the radiator and it's dropping slowly (the electric fans would normally kick on and off a few times).

The gauge does not seem to be sticky, so I have to assume for now that the temperature readings are real. Does anyone have an idea as to what's going on? I've never seen this "stair-step" with temperatures.

Oh please. The consensus at moparts? The Contour fans are OE fans that probably have hundreds, if not thousands, of hours of design and testing behind them. Too restrictive my ***. The Contour fans on my car have never been too restrictive, any time I'm doing more than 35 mph for more than a few miles they don't run and my car cools down to within a few degrees of the thermostat temp. At freeway speeds my water temp drops to the thermostat temperature even with the air temps are hot. If the fan shroud was too restrictive freeway speeds would result in the temperature climbing, that's not what happens. If your temps are climbing at higher speeds, I'd be willing to bet it's not your fans but the rest of your cooling system.

As for your temperatures, it's called heat soak. As you're driving the heat is building up in the engine. Remember, you're looking at the water temperature, and at 160 your engine and internal components are not as hot as they're going to get. Your 30 mph speeds were enough to keep the temperature from rising further even though your engine was creating more heat, but your speed wasn't fast enough to move the temperature back down. When was the temperature climbing? When you were turning around. So all the engine components were getting hotter, and as you were turning around you weren't moving any air so the water temperatures climbed rapidly.

Your results are exactly what you should see. If you'd driven a little faster, or a little further, your temperatures would have come down more. But the cumulative effects of the short drive and turn arounds where the heat was building were outpacing your cooling capabilities without fans. If you'd been running the fans on your 3 point turns it would have maintained better.