Electric or not?

[67_Slimer]

OK , I've asked about my cooling system before regarding my current setup. Factory style clutch fan with a cheap electric fan pushing for backup. Car will run at 190 on a hot day but , now I'm wondering , what would be my advantages or disadvantages be if I completely eliminate my clutch fan and run just a really high quality electric fan? Do I run a puller or pusher? Or both? I'm just thinking about freeing up some strain on my new water pump. Please Give me your input on either way you think. Thank you.

 

[dano]

190 doesn't hurt anything especially if that is where it maxes out on a hot day. What do you consider a hot day?

Have you adjusted the tune? Retarded initial and/or to lean will make the engine run hot.

 

[67_Slimer]

190 doesn't hurt anything especially if that is where it maxes out on a hot day. What do you consider a hot day?

Have you adjusted the tune? Retarded initial and/or to lean will make the engine run hot.

anything over 80 degrees is considered "hot" I'm not only thinking about temperature , I'm also considering freeing up my water pump work load. Just looking for other options.

 

[Dana67Dart]

WHY do people hate mechanical fans. THEY WORK.

 

[CRUZE 418]

Water pump work load? Loose the electric fan. Water pump work load???

 

[dano]

anything over 80 degrees is considered "hot" I'm not only thinking about temperature , I'm also considering freeing up my water pump work load. Just looking for other options.

Have you verified the clutch works? If not this can be done with a heat gun. Do you run a fan shroud? What were the temps before the electric fan was added?

 

[33IMP]

As somebody who has to run electric fans, don't. IF I could run mechanical fans in my applications, I would.

But IF you decide to run an electric fan or two.... pullers are way more efficient, and you'll need a shroud. (And make sure your pullers are wired to pull, not push).

 

[Dana67Dart]

Factory style clutch fan with a cheap electric fan pushing for backup. Car will run at 190 on a hot day but

OP DOES NOT HAVE A COOLING PROBLEM "car will run at 190 on a hot day..."

Pusher fan is a "BACKUP" for traffic

OP only wants to complicate his life by replacing a fully functional cooling solution with a problematic, more complex cooling (or lack there of) solution


IF IT AIN'T BROKE DONT FIX IT!

 

[72bluNblu]

First, 190° on a hot day isn't running hot. In fact, the factory thermostat for many of these cars was a 190°, so, it wasn't gonna ever run cooler than that once it's warmed up unless you've changed the thermostat. Even if you have changed the thermostat that will only lower the temp on cold days, because the factory system was designed to operate from 190° to 210° and the thermostat only sets the floor, not the ceiling.

Second, your cheap pusher fan in front of the radiator blocks air flow when not in use, and can actually limit airflow WHEN in use if you're running it when you don't need it (ie, any speed over 30mph or so). Cheap pushers are a band aid for a problem you haven't fixed the right way.

A high quality, well designed electric fan set up is more efficient than a mechanical fan, especially the very basic mechanical fans these cars have. You can control exactly when it's running and when it's not to maintain a narrow operating temperature range and you're not wasting energy by spinning a bunch of heavy parts when you don't need them.

But you can't just slap on an electric fan that will get the job done on these cars. You need to pull in the neighborhood of 3,000 cfm to make a stand alone electric fan capable of doing the job, and that means you're gonna need 40-50amps when that thing first starts. And the stock alternator and wiring on these cars isn't gonna do that. So you need a relay set up and larger alternator, in addition to a fan that fits the radiator and the space you have to work with. And then you need a good controller to take care of running the fan, not just a stupid on/off switch or a constant on. You actually need a good controller. And that's the minimum, because again the stock wiring on these cars was never meant to supply something that could just yard 40-50 amps out of it at the flip of a switch.

If you're not going to do all that, then you need to keep your mechanical fan. We don't need any more people on here that **** on electric fans because they picked the wrong one, didn't reliably supply it with enough power and ran a cheap controller (or none at all).

So run a good fan shroud, and make sure you have the proper pulley ratios for your water pump and your cars accessory set up, because there were different ratios for different output water pumps and accessory packages.

 

[Inertia]

anything over 80 degrees is considered "hot" I'm not only thinking about temperature , I'm also considering freeing up my water pump work load. Just looking for other options.

The work load you unload from the pump is transfered to the alternator in workload to drive the electric fan. ( Edited )
Then of course you have to account for the extra friction ( parasitic h/p loss) caused by the belts and bearings.
If you could eliminate friction you would be able to accomplish "perpetual motion".

Good luck

 

[67_Slimer]

Have you verified the clutch works? If not this can be done with a heat gun. Do you run a fan shroud? What were the temps before the electric fan was added?

So I know the clutch works but I'm going to try taking the electric fan off but my only question is this. I understand that the electric fan can be blocking air flow , but when it's on , wouldn't it be flowing more air than if it was removed? Also , I'm going to be looking into putting a shroud.

 

[67_Slimer]

The work load you unload from the pump is transfered to the alternator in workload to drive the electric pump.
Then of course you have to account for the extra friction caused by the belts and bearings.
If you could eliminate friction you would be able to accomplish "perpetual motion".

Good luck

Electric pump? I'm not putting an electric pump , Electric fan.

 

[67_Slimer]

First, 190° on a hot day isn't running hot. In fact, the factory thermostat for many of these cars was a 190°, so, it wasn't gonna ever run cooler than that once it's warmed up unless you've changed the thermostat. Even if you have changed the thermostat that will only lower the temp on cold days, because the factory system was designed to operate from 190° to 210° and the thermostat only sets the floor, not the ceiling.

Second, your cheap pusher fan in front of the radiator blocks air flow when not in use, and can actually limit airflow WHEN in use if you're running it when you don't need it (ie, any speed over 30mph or so). Cheap pushers are a band aid for a problem you haven't fixed the right way.

A high quality, well designed electric fan set up is more efficient than a mechanical fan, especially the very basic mechanical fans these cars have. You can control exactly when it's running and when it's not to maintain a narrow operating temperature range and you're not wasting energy by spinning a bunch of heavy parts when you don't need them.

But you can't just slap on an electric fan that will get the job done on these cars. You need to pull in the neighborhood of 3,000 cfm to make a stand alone electric fan capable of doing the job, and that means you're gonna need 40-50amps when that thing first starts. And the stock alternator and wiring on these cars isn't gonna do that. So you need a relay set up and larger alternator, in addition to a fan that fits the radiator and the space you have to work with. And then you need a good controller to take care of running the fan, not just a stupid on/off switch or a constant on. You actually need a good controller. And that's the minimum, because again the stock wiring on these cars was never meant to supply something that could just yard 40-50 amps out of it at the flip of a switch.

If you're not going to do all that, then you need to keep your mechanical fan. We don't need any more people on here that **** on electric fans because they picked the wrong one, didn't reliably supply it with enough power and ran a cheap controller (or none at all).

So run a good fan shroud, and make sure you have the proper pulley ratios for your water pump and your cars accessory set up, because there were different ratios for different output water pumps and accessory packages.

This was so well said. Thank You for this. I am guilty of doing a few of these things and will correct them!! I'll keep you posted with the results.

 

[dano]

So I know the clutch works but I'm going to try taking the electric fan off but my only question is this. I understand that the electric fan can be blocking air flow , but when it's on , wouldn't it be flowing more air than if it was removed? Also , I'm going to be looking into putting a shroud.

Anything in front of the radiator core will block flow. So yes, removing it and straining any bent fins will help, how much its hard to say without testing.

Shroud will help as will the hood seals at the front and rear and I still say if you're looking to eek out a few less degrees, add some timing and see, then add a hair of fuel and see. It will take a few test drive to shake it all out. Document the changes so you can go backwards if nothing works out.

72bluNblu brings up a good point on pully ratio. Are yours stock and if so where they original to the car/engine or a mismatch?

 

[Inertia]

Electric pump? I'm not putting an electric pump , Electric fan.

I mis-typed, - meant electric fan

 

[67_Slimer]

Anything in front of the radiator core will block flow. So yes, removing it and straining any bent fins will help, how much its hard to say without testing.

Shroud will help as will the hood seals at the front and rear and I still say if you're looking to eek out a few less degrees, add some timing and see, then add a hair of fuel and see. It will take a few test drive to shake it all out. Document the changes so you can go backwards if nothing works out.

72bluNblu brings up a good point on pully ratio. Are yours stock and if so where they original to the car/engine or a mismatch?

Thank you! , I call my Dart frankenstein , other than glass , nothing is original so who knows with the pulleys lol

 

[dano]

Thank you! , I call my Dart frankenstein , other than glass , nothing is original so who knows with the pulleys lol

Same here. Mine was a basket case.

 

[72bluNblu]

I understand that the electric fan can be blocking air flow , but when it's on , wouldn't it be flowing more air than if it was removed? Also , I'm going to be looking into putting a shroud.

Actually with the fan on it can actually still restrict air flow by creating drag. The fan is designed to push a certain amount of air, let's just call it 1,000 cfm for a nice round number. So the fan is on and it's pushing 1k cfm when you're sitting still, adding that to the air the mechanical fan is pulling from the other side and everything is nice.

But then you start driving. And at say, 30 mph or more you're trying to stuff a whole hell of a lot more than 1,000 cfm through that fan because of the incoming air velocity. Well, the fan only wants to push 1,000 cfm, so now that electric fan is creating a **** ton of drag. Is it going to allow more than 1,000 cfm through? Absolutely. Will it let through as much as would come through without it in the way? Absolutely not.

It depends on a ton of things, fan blade design, the RPM the fan spins at, how many CFM it was supposed to flow and the incoming air speed that it was designed around. If it's a cheap fan it may have only ever been tested when stationary. But the bottom line is, at some point that pusher fan spinning in front of the radiator is going to create more drag/resistance than it's going to move air. Same reason why propeller driven aircraft have a maximum top speed, or why even jet engine aircraft have a maximum top speed- at some point the incoming air speed is a problem too big for the fan, propeller, or turbine to handle. For propellers things get problematic when you get close to 500 mph, for typical jet engines you actually need subsonic air coming in and that gets real tough when you approach Mach 4 (reason why the SR71 has giant engine nacelles). So then you have to go SCRAM jet and have supersonic incoming air, buuuuut the SCRAM only works at Mach 5+ so you gotta go that fast before you start.

Anyway, I digress. Yes, the cheap electric fan running in front of your radiator will absolutely restrict air flow when the car is moving fast enough to put more air through it than it was designed to move by itself.

Thank you! , I call my Dart frankenstein , other than glass , nothing is original so who knows with the pulleys lol

Probably worth measuring the diameter of your pulleys and calculating the ratio of your crank pulley to water pump pulley. The non-AC cars had HD water pumps (8 vane and a larger diameter impeller) and a .95:1 ratio, the AC cars ran a 6 vane water pump and a smaller diameter impeller but a 1.3 to 1.4:1 ratio depending on the model/engine. So they spun a lower output pump at a faster RPM, with the fan speed probably being the thing the factory wanted to improve the most.

 

[67_Slimer]

Actually with the fan on it can actually still restrict air flow by creating drag. The fan is designed to push a certain amount of air, let's just call it 1,000 cfm for a nice round number. So the fan is on and it's pushing 1k cfm when you're sitting still, adding that to the air the mechanical fan is pulling from the other side and everything is nice.

But then you start driving. And at say, 30 mph or more you're trying to stuff a whole hell of a lot more than 1,000 cfm through that fan because of the incoming air velocity. Well, the fan only wants to push 1,000 cfm, so now that electric fan is creating a **** ton of drag. Is it going to allow more than 1,000 cfm through? Absolutely. Will it let through as much as would come through without it in the way? Absolutely not.

It depends on a ton of things, fan blade design, the RPM the fan spins at, how many CFM it was supposed to flow and the incoming air speed that it was designed around. If it's a cheap fan it may have only ever been tested when stationary. But the bottom line is, at some point that pusher fan spinning in front of the radiator is going to create more drag/resistance than it's going to move air. Same reason why propeller driven aircraft have a maximum top speed, or why even jet engine aircraft have a maximum top speed- at some point the incoming air speed is a problem too big for the fan, propeller, or turbine to handle. For propellers things get problematic when you get close to 500 mph, for typical jet engines you actually need subsonic air coming in and that gets real tough when you approach Mach 4 (reason why the SR71 has giant engine nacelles). So then you have to go SCRAM jet and have supersonic incoming air, buuuuut the SCRAM only works at Mach 5+ so you gotta go that fast before you start.

Anyway, I digress. Yes, the cheap electric fan running in front of your radiator will absolutely restrict air flow when the car is moving fast enough to put more air through it than it was designed to move by itself.


Probably worth measuring the diameter of your pulleys and calculating the ratio of your crank pulley to water pump pulley. The non-AC cars had HD water pumps (8 vane and a larger diameter impeller) and a .95:1 ratio, the AC cars ran a 6 vane water pump and a smaller diameter impeller but a 1.3 to 1.4:1 ratio depending on the model/engine. So they spun a lower output pump at a faster RPM, with the fan speed probably being the thing the factory wanted to improve the most.

Thank you so much , I put that secondary electric fan on for traffic situations but now it hurts me when I'm driving. I guess it's pick my poison lol. Thank you again for making some really good points.

 

[dano]

Thank you so much , I put that secondary electric fan on for traffic situations but now it hurts me when I'm driving. I guess it's pick my poison lol. Thank you again for making some really good points.

You actually want the heat if you live in a place where it can get humid.

 

[str12-340]

electric fan on a street car? I vote NO!!!

 

[72bluNblu]

electric fan on a street car? I vote NO!!!

Lol. So your daily driver doesn't have an electric fan? Your PT cruiser certainly did

 

[Dana67Dart]

Lol. So your daily driver doesn't have an electric fan? Your PT cruiser certainly did

Modern cars are designed from the ground up with electric fans not adapted from misc. parts that MIGHT work.

I know you have had great success with E fans but MANY others have not.

The number of "my engine overheats" posts that start with "Aluminum" and end with "Electric fans" is staggering as compared with the "stock cooling system" posts

 

[RLF Cuda]

Due to using an aluminum WP on my '68 340 (originally cast iron), the 3/4" longer snout and unidentified damage to the core support coupled with using an aluminum radiator which has the core further back towards the engine, I ended up having to run dual 10" fans instead of the 7-blade fan I wanted to run. This meant a lot of other changes including much higher output alternator and associated HD wiring for the added current, and dual thermostatic switches and relays needed to control the dual fans. I used Engineered Cooling Products for the radiator and fan, and it will cool the 340 to 180°F on cool days and 190-200°F on 95°F days. So, good enough for now. But would I do this again, no. I would try to use the factory parts as best I could including a good 5 or 7 blade fan with viscous drive, a shroud and a 4-core radiator although the 3-core stock radiator should work fine.

Photo shows direct wiring of fan to alternator output post for shortest line from power to fan relays. Relay wiring goes to manifold fittings. Currently I have both fans run off a single 180°F switch but may go to dual switches with one at 180 and the other at 195°F.

Biggest complaint is the fans are noisy from the outside although I can barely hear them inside the car.

 

[Inertia]

I had a big Cherokee 2 speed electric fan on our last 4 cyl racecar.
When that fan came on full, - at idle, engine rpm would decrease significantly
(200h/p)