Run electric fans all the time?

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Interesting information on fan dynamics, thanks. My background is EE, not ME (or aeronautical engineering) :rolleyes:
Don't airplane propellers windmill even when feathered, though?

Anyway that was my concern - that the Contour fan would not windmill when off, which was confirmed above. But if that actually helps airflow, then they should stay off at speed!

I installed a high-flow thermostat with no change. Probably time for a modern aluminum radiator ;)
 
Well both types have plus/minus things about them. Electric is quieter on cruise, less of a paracite, cools better at idle, water pump lasts longer? but more to go wrong with electric than mechanical.

There are pros/cons to everything. Mechanical is simpler, but not as efficient. Electric is more efficient, but you have to upgrade the electrical system and run a good controller. And sure, stuff to fail- relays, fan motors, controllers, etc.

Of course, when something in the mechanical system does fail, it can do so catastrophically. I've seen fan blades tossed, water pump shafts fail and send the fan blades into the radiator, etc.

Thanks but no thanks
I will stay with my good old reliable belt driven 7 blade fan they just work
Like I told you before I have been that route spent the money, upgraded electricial it just is not worth it.
I know all the modern day crap blah, blah, blah, yada, yada, yada
I am old school and proud of it I dont/want all that bullshit
And yes I do have several modern vehicles that have electric fans and they work very well, but not in my classic cruiser.

I'm not trying to tell you what you should run on your car, if your mechanical system works for you then keep it. All I'm saying is that there's no reason why an electric fan system can't work. Set up properly electric fan systems are more efficient and plenty capable. That doesn't mean you have to convert your car over. It just means that if you tried an electric fan that didn't work it wasn't because it was an electric fan, it's because it wasn't set up properly.

As for as the upgrades, most people upgrade their electrical system anyway. Amp meter bypasses are commonplace, very few people run stock output alternators anymore. My alternator is only a 100 amp, all I did was run an amp meter bypass and add the relays for the fan. Nothing crazy, I didn't rewire the whole car.

Mechanical systems fail too, they break fan belts, chew up water pumps, toss fan blades, etc. And they run all the time, or most of the time depending on the fan clutch. Modern electric fans, especially those designed for OE applications, are designed to last hundreds of thousands of miles without maintenance. That's more than the original mechanical system was designed for.

Interesting information on fan dynamics, thanks. My background is EE, not ME (or aeronautical engineering) :rolleyes:
Don't airplane propellers windmill even when feathered, though?

Anyway that was my concern - that the Contour fan would not windmill when off, which was confirmed above. But if that actually helps airflow, then they should stay off at speed!

I installed a high-flow thermostat with no change. Probably time for a modern aluminum radiator ;)

What an airplane propeller does is very specific to the aircraft. Some are direct drive off the crankshaft, some have gearboxes, some are direct gear reduction. And then some aircraft have variable pitch propellers too, which is a factor.

A lot of times it isn't about drag though. On an aircraft small enough not to have an onboard APU all the electric and hydraulic power comes from the engine spinning. If you have some kind of engine failure, you keep the propeller spinning if you can because in a lot of situations/aircraft that will keep your magneto's and your hydraulic pump turning too. So you may lose glide distance but you keep power and control. And if you have a variable pitch prop you may change the pitch to reduce some drag but still keep it spinning for power.

In some cases a multi-engine military aircraft can shut down an engine (or two in some cases) and lock them out to extend range, like a P3 on a long anti-subarine mission. But it has the other engines to maintain electric and hydraulic power. A civilian aircraft may not have that capability even if it is a multi-engine.

So it's complicated. :p

My degree is Aerospace Engineering, so, I spent a lot more time on jet and rocket engines than I did on prop driven stuff. But that's how I understand it anyway.
 
There are pros/cons to everything. Mechanical is simpler, but not as efficient. Electric is more efficient, but you have to upgrade the electrical system and run a good controller. And sure, stuff to fail- relays, fan motors, controllers, etc.

Of course, when something in the mechanical system does fail, it can do so catastrophically. I've seen fan blades tossed, water pump shafts fail and send the fan blades into the radiator, etc.

My degree is Aerospace Engineering, so, I spent a lot more time on jet and rocket engines than I did on prop driven stuff. But that's how I understand it anyway.

Agreed, when I was a kid, my dad had a 1983 Ford Mustang GT 5.0 Convertible, the fan clutch failed and took out the water pump and timing cover with it. On that car it had a serpentine belt with a mechanical fuel pump - which they didn't make timing covers for so my dad had to have an EFI one modified. So the car was off the road for months. We got lucky it didn't mess up the radiator and shroud along with it.

My uncle worked at Bosch when they were designing those Contour fans, he said its one of the most difficult applications he had seen, the fans almost touch the exhaust manifold, engine bay tightly packed, small grille openings, very thin radiator, A/C, and it had to cool with the A/C on max in death valley in the summer. My fan is OEM and is over 20 years old already.

I'm a mechanical engineer but I work on braking systems for a living. Also kind of into planes, the windmill restart videos of a Russian Tupelov TU-95 at altitude are interesting to say the least.
 
What's really ludicrous is saying that a mechanical fan sucks up 15 or more hp ;
1) that would have to be a max-effort direct drive fan,
2) spinning on a stationary engine., like on a dyno, so you can measure it.
3) at peak horsepower say 5000plus rpm.

That will never happen in real life, because;
1) your engine will never ever be at 5000 rpm, in still air, and working. It ain't a generator.
2) I can't see any HotRodder ever putting a 7-blade, hi-attack, all-steel, direct drive fan on his engine, without a clutch, cuz nobody wants to see a 7-blader blow up, at 5000/6000/7000rpm .. and the smart money is on a thermostatically controlled clutch.
3) your V8-street car by 5000 rpm in first gear, has more power than the chassis can handle, so right off the bat even a direct-drive fan is not costing you any ET. It's all going up in smoke at the rear tires.
By 5000 in second-gear with say 3.55s and a TF-auto, your street car is doing about, lets see now ,oh I know; waaaaay past the speed limit, so again even the direct-drive 7-blader is costing you nothing. But Ok , I get that not everybody lifts at 65mph, so 5000 in second comes to about 78 mph. So the airspeed hitting the rad is 78mph. I got no idea what the airspeed is on the engine side , and I don't care; that clutched 7-blader is simply going along for a free ride, costing you nothing, because it has long-ago de-coupled. Yes it's windmilling so what! there's a 78 mph wind ramming thru the rad doing a fine fine job of cooling it.
4) My clutched 7-blade,hi-attack,all-steel fan, has been 100% reliable since the day I installed it, keeping my engine at exactly the temp I adjusted it to; I mean exactly. And I never even look at the temperature gauge, anymore.

But back to OPs question;
As you have detailed in post #1, and with supporting statements following;
if I was in your quandry,
I would try it
 
I might have gone with a more conventional clutch fan, except that there isn't enough radiator core clearance even with the shortest clutch I could find. Since the engine is in the stock position, the radiator core position must be the problem. Another reason it might be time to try a properly sized aluminum one.

The issue with a mechanical fan isn't so much the (alleged) hp loss at high rpm, but that it makes the least cfm when stopped or crawling at idle - which is often when you need it the most, in traffic on a hot day. No problem with the Contour fans which move a lot of air.

Anyhow, as you, I and others have said, I can try it and see ;)
 
I might have gone with a more conventional clutch fan, except that there isn't enough radiator core clearance even with the shortest clutch I could find. Since the engine is in the stock position, the radiator core position must be the problem. Another reason it might be time to try a properly sized aluminum one.

The issue with a mechanical fan isn't so much the (alleged) hp loss at high rpm, but that it makes the least cfm when stopped or crawling at idle - which is often when you need it the most, in traffic on a hot day. No problem with the Contour fans which move a lot of air.

Anyhow, as you, I and others have said, I can try it and see ;)

You won’t have an idle speed issue if you overdrive the pump, which overdrives the fan.

Honestly, at idle you don’t make much heat, so pump speed is at least as critical as fan speed.
 
You won’t have an idle speed issue if you overdrive the pump, which overdrives the fan.

Honestly, at idle you don’t make much heat, so pump speed is at least as critical as fan speed.

True, but I don't want to blow anything up on the rare occasions when I wind it up to 7000 (crank) rpm, either. It doesn't idle all that efficiently with a 272@.050 cam...
 
You won’t have an idle speed issue if you overdrive the pump, which overdrives the fan.

Honestly, at idle you don’t make much heat, so pump speed is at least as critical as fan speed.

True, but I don't want to blow anything up on the rare occasions when I wind it up to 7000 (crank) rpm, either. It doesn't idle all that efficiently with a 272@.050 cam...

This is exactly why electric fans end up being more efficient. Because at idle you need to move more air but not necessarily as much water. And at 7k rpm if you’ve overdriven the fan so it cools well at idle you run the chance of cavitation on the pump.

And you’re losing a ton of horsepower spinning the fan at 7k when you’re moving at speed and don’t really need the airflow from the fan. Even with a clutch you’re spinning the fan at 30% or more when you don’t need it at all.

With electric fans you can get your maximum cfm at idle where you need it because you’re sitting still, and have the fans completely off when you’re spinning max rpms and moving at speed.
 
I suppose you are, and nothing outflows the cooling fan on a Cummins.
 
What's really ludicrous is saying that a mechanical fan sucks up 15 or more hp ;
1) that would have to be a max-effort direct drive fan,
2) spinning on a stationary engine., like on a dyno, so you can measure it.
3) at peak horsepower say 5000plus rpm.

That will never happen in real life, because;
1) your engine will never ever be at 5000 rpm, in still air, and working. It ain't a generator.
2) I can't see any HotRodder ever putting a 7-blade, hi-attack, all-steel, direct drive fan on his engine, without a clutch, cuz nobody wants to see a 7-blader blow up, at 5000/6000/7000rpm .. and the smart money is on a thermostatically controlled clutch.
3) your V8-street car by 5000 rpm in first gear, has more power than the chassis can handle, so right off the bat even a direct-drive fan is not costing you any ET. It's all going up in smoke at the rear tires.
By 5000 in second-gear with say 3.55s and a TF-auto, your street car is doing about, lets see now ,oh I know; waaaaay past the speed limit, so again even the direct-drive 7-blader is costing you nothing. But Ok , I get that not everybody lifts at 65mph, so 5000 in second comes to about 78 mph. So the airspeed hitting the rad is 78mph. I got no idea what the airspeed is on the engine side , and I don't care; that clutched 7-blader is simply going along for a free ride, costing you nothing, because it has long-ago de-coupled. Yes it's windmilling so what! there's a 78 mph wind ramming thru the rad doing a fine fine job of cooling it.
4) My clutched 7-blade,hi-attack,all-steel fan, has been 100% reliable since the day I installed it, keeping my engine at exactly the temp I adjusted it to; I mean exactly. And I never even look at the temperature gauge, anymore.

But back to OPs question;
As you have detailed in post #1, and with supporting statements following;
if I was in your quandry,
I would try it

I re-watched the engine masters where they test these fans on a 350hp 350 chevy. The clutch fan killed 14hp and 7 lb ft at peak but it was all across the range. 7 blade fixed fan killed 30.4hp and 18.8 lb ft of torque and that is with a radiator in place.

So maybe you're only killing 10hp then? That vs 0? Sounds like cheap power then.

My car can hook on the street at 5000 in 1st with a 6-speed so maybe you kept it old school with Radial T/As (which also like mechanical fans are also antiquated)? That's an odd statement honestly. If that was the case I guess all our cars are junk then?

I also don't need to look @ the temp gauge. The Contour setup has been 100% reliable from day one also. Been over 7 years for me. I purposely let it go up 10 degrees before the fan comes on so its on as little as possible. Not that the car cares.
 
So maybe you're only killing 10hp then? That vs 0? Sounds like cheap power then.
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.
 
A quick Google shows that a typical car alternator is 55% efficient, not "10-20%". Also, 40 amps is what the well-regarded Contour fans draw when both are on full speed. No one would ever have two 40 amp fans.
So your 9.65 hp drain is WAY overestimated. That'd also be pretty hard to transmit through a single small V-belt going around a 2.5" pulley...
 
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.

A quick Google shows that a typical car alternator is 55% efficient, not "10-20%". Also, 40 amps is what the well-regarded Contour fans draw when both are on full speed. No one would ever have two 40 amp fans.
So your 9.65 hp drain is WAY overestimated. That'd also be pretty hard to transmit through a single small V-belt going around a 2.5" pulley...

Again, you couldn't be more wrong. Except maybe about not knowing anything. I do know how alternators work, fans work

I tested my own setup at full speed sitting in my garage, and it draws 20A when running, verified with an inductive clamp multimeter, but most of the time its going to run at the lower speed which is 15A. So 15x13.5=202.5W. Then we convert to hp by dividing by 745.7 = 0.272 hp and then remove alternator efficiency at even for the benefit of the doubt, 50% efficiency, 0.544 hp loss. So even the most bad *** electric fan anyone can think of costs about 1hp. Inrush current is 35-38A to start from a stop but that is in the range of 1 second. The battery will take most of the hit there.

Your mechanical fan takes more than 1hp to turn always. The efficiency is not there with a mechanical fan which is why they have basically disappeared from anything modern.

The fan isn't generating power when you go a little faster. It's still a cost, its rotating weight attached to the crankshaft that you have to accelerate anytime the RPM increases. You would be indicating that air passing 90 degrees over a device running at a certain RPM is making the fan spin and applying power to the crank, which is not happening. I'm sure there is a condition where there is some amount of drag loss on the fan which would reduce the amount of energy you lose by moving it. Not any real way to quantify, but I'm driving down the road and the electric fan costs me literally nothing because its literally not on and not spinning. The RPM of an electric fan is also decoupled from accellerating or decelerating the engine.

My engine is also running a lot cooler than 207F. Going down the road its 180-185 and the fans turn on at 195 and off at 192.
 
You won’t have an idle speed issue if you overdrive the pump, which overdrives the fan.

Honestly, at idle you don’t make much heat, so pump speed is at least as critical as fan speed.

Gotta say , my engine makes a hell of a bunch of heat at idle ------------
 
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.
 
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.

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.

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.
 
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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.

OK... so even a steady 30 mph isn't enough air to do away with the need for a fan?? I always thought that was fast enough, but apparently not!

My temps do not climb at higher speeds, they just don't go down (like yours do). I expect to run just above t-stat temp when doing 60 mph, and that is not what happens, either with the old 26" copper rad or the new 26" aluminum one, and a high-flow stat.

The water pump is slightly underdriven (stock non-a/c pulleys). I'm going to replace the pump with a Flowkooler high-flow unit, and will also then find out what's in there (hope it's not a 6-vane a/c pump, I can't recall).
 
OK... so even a steady 30 mph isn't enough air to do away with the need for a fan?? I always thought that was fast enough, but apparently not!

My temps do not climb at higher speeds, they just don't go down (like yours do). I expect to run just above t-stat temp when doing 60 mph, and that is not what happens, either with the old 26" copper rad or the new 26" aluminum one, and a high-flow stat.

The water pump is slightly underdriven (stock non-a/c pulleys). I'm going to replace the pump with a Flowkooler high-flow unit, and will also then find out what's in there (hope it's not a 6-vane a/c pump, I can't recall).

Well 30 mph was enough to do without the fans, the temperature was dropping when you were actually driving. It just wasn’t fast enough to drop the temperature enough in the short distance you drove to make up for the temperature rise when you were turning around. All your temperature rise was when you were turning around.

Your under-driven water pump could be the issue. Mine is 1:1 with a high flow pump.
 
Thanks. That is also my current diagnosis :)

Aren't there only two ratios for the B/RB, either 0.95 or 1.30? Anyhow I'm going to try the high flow pump and see how THAT goes.

How big an engine are you successfully cooling with the Contour fans?
 
We both have 340s but they are hopped up and also don't even need the high speed. I'm not sure that you're too far off from having this right.

I also read how you have your switch in the upper radiator hose, probably not the best thing, you'd be better off with the switch below the thermostat. Threading it into one of these is a better setup:
Meziere Water Neck Spacers WN0028U


This is the car that those came in so they aren't kings of airflow coming though the front.
9608-MTRP-02-I-WRAP-C.jpg
 
True... but it's also trying to cool only a small V6, not a big-cam 451 :)

When I say the temp only fell to 196, I mean it came down within a few seconds to that level and but did not continue dropping. It stabilized at the new "stair step" level.

Edit: Thanks for the link to the Meziere spacer! I'll definitely get one soon :)
 
Wow... and I thought my E39 BMW 540i had a tight engine compartment!

BTW, I looked closely at that Meziere spacer - and it goes above the thermostat, so the sensor would be (thermally) effectively in the same place as mine is, just a few inches closer to the engine. The 'stat still sits in the water pump flange.
 
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