I might have an answer to why an electric fan could be more efficient in some tests and a mechanical fan could be a drain at peak power. @jrichker does this make sense from an electrical and physics view?
The electric fans operate at about at their rated speed independent of engine speed. The motors pull no more current at idle than at 6000 engine RPM. So they are running at the same efficiency all the time. So they are drawing the same watts or hp when on, once past the start up peak.
The mechanical fan needs to pull enough air at idle to cool the engine, yet it ends up being spun much faster, possibly overdriven, as rpm’s increase. So not counting any clutch slippage, by the time the engine hits a shift point at the track or the top of a dyno run, the mechanical fan is trying to do at least 6x the work of the electric fans. If cavitation, pressurization of the engine bay, or the radiator and air flow potential of the car’s design are limiting free airflow, that 6x figure could be a minimum.
Unless there is a hole in this theory, I can live with it and gladly support the idea that an OEM quality electric fan set up is a good performance upgrade. I still like simple solutions, but as we already have electronics involved, we might as well go with a more efficient tech.
The electric fans operate at about at their rated speed independent of engine speed. The motors pull no more current at idle than at 6000 engine RPM. So they are running at the same efficiency all the time. So they are drawing the same watts or hp when on, once past the start up peak.
The mechanical fan needs to pull enough air at idle to cool the engine, yet it ends up being spun much faster, possibly overdriven, as rpm’s increase. So not counting any clutch slippage, by the time the engine hits a shift point at the track or the top of a dyno run, the mechanical fan is trying to do at least 6x the work of the electric fans. If cavitation, pressurization of the engine bay, or the radiator and air flow potential of the car’s design are limiting free airflow, that 6x figure could be a minimum.
Unless there is a hole in this theory, I can live with it and gladly support the idea that an OEM quality electric fan set up is a good performance upgrade. I still like simple solutions, but as we already have electronics involved, we might as well go with a more efficient tech.
You also have the fact that a good electric fan controller can disable the fan at cruise or WOT. I've seen this done with some OEM fan controllers, and the Megasquirt can be programmed to do this as well.
Many people use temp switches on the relay ground to run their fan, but you can also easily wire in a Normally closed relay to the pos coil side of the relay that opens when the OEM WOT relay trips. That would open the relay turning the fan off until you are done doing all your WOT monkey-business.
Really, you need the fan under 40MPH. Above that, there should be more than enough airflow through the radiator provides your radiator skirting is all in place and the fins/radiator are in good shape. You could probably do a little Arduino work work with the signal from the VSS to turn the fan off above 40MPH as well, but now we are getting carried away.
Many people use temp switches on the relay ground to run their fan, but you can also easily wire in a Normally closed relay to the pos coil side of the relay that opens when the OEM WOT relay trips. That would open the relay turning the fan off until you are done doing all your WOT monkey-business.
Really, you need the fan under 40MPH. Above that, there should be more than enough airflow through the radiator provides your radiator skirting is all in place and the fins/radiator are in good shape. You could probably do a little Arduino work work with the signal from the VSS to turn the fan off above 40MPH as well, but now we are getting carried away.
An Aduino to control fan relays is an interesting idea. Temp, speed, WOT bursts and AC function would be just enough overkill if it was reliable.
Edit: it does not take long to hit 40 at WOT. On a hot day, it’s easy to tell when the AC compressor is off, so I’d want to watch the temp gauge while testing it.
As far as programming, I bet some school tech class uses Aduino or the Ras Pi units. So either an offspring or one of their friends might be the quick way to learn the programming.
Edit: it does not take long to hit 40 at WOT. On a hot day, it’s easy to tell when the AC compressor is off, so I’d want to watch the temp gauge while testing it.
As far as programming, I bet some school tech class uses Aduino or the Ras Pi units. So either an offspring or one of their friends might be the quick way to learn the programming.
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I'm sure it could be done. Someone just needs to spend the time to write the code.
Can prob wire in an GM temp sensor in the rear port of the intake manifold, and tap into the WOT relay and VSS. Maybe 5 wires, program the Arduino (or raspberry pi) and you have a cheap little fan controller than you can modify to your liking. Have it activate a Bosch 75A relay and keep it all low voltage.
I have an arduino or two kicking around. If only i had time....
Just grabbed the fans out of a 98 mystique. Boy, was it hot! (100 degrees here smh) I saw 99-02 on internet, but this said 98 on the car and had dual fans. So i figured they were the same. Alternator out of a 97 v6 mustang.
About to decide how i want to trigger these fans. Either slide in radiator probe or thermostat screw in.
About to decide how i want to trigger these fans. Either slide in radiator probe or thermostat screw in.
From the mustang 360 article: "For wiring, we used a T-tap connector to pick up the key-on positive signal from the coolant overflow sensor harness and connected that to the key-on source on the temperature control unit. From there, we ran a wire to the 40-amp relay and its switch terminal (86 pin). The relay was then grounded on the 85 pin and a 12-volt constant power source was fitted to the 30 pin. The positive 12-volt output (87 pin) was then connected to the electric fan positive leads. "
For the 12v constant power source, I can just run that to the positive starter solenoid for "pin 30" on the relay? Doing the samething here, just using Amazon product ASIN B000C3DD7MView: https://www.amazon.com/gp/product/B000C3DD7M/ref=ox_sc_act_title_2?smid=ATVPDKIKX0DER&psc=1
instead of flex a lite 31147.
For the 12v constant power source, I can just run that to the positive starter solenoid for "pin 30" on the relay? Doing the samething here, just using Amazon product ASIN B000C3DD7MView: https://www.amazon.com/gp/product/B000C3DD7M/ref=ox_sc_act_title_2?smid=ATVPDKIKX0DER&psc=1
instead of flex a lite 31147.
Getting the fans from a '98 Mystique is perfect. How much of the OEM wiring did you grab? You will want the OEM 70 amp relay(s). Are you going to run single speed or dual speed?
My suggestion is have your temp sensor (fan control switch) on the discharge side of the rad (mine is in the lower rad hose). This will allow the rad to do its job and then only when needed will the fans come on.
If you install the sensor/switch in the thermostat housing (or anywhere in the intake manifold) you will be reading the engine temp before the rad gets a chance to cool it. If I am out on the highway cruising my fans will not come on until I slow down in traffic or stop. That has been well over an hour on a few occasions. That is because the air flowing through the rad cools the coolant enough that the fan switch after the rad does not get triggered. Basically only running the fans when its needed.
A sensor or fan trigger switch in T-stat housing or intake will trigger fans when engine gets up to the switch temp (depending on T-stat), thus running the fans when they may not be needed. Remember with the fans you are trying to cool coolant, not the engine. That's the coolants job.
My suggestion is have your temp sensor (fan control switch) on the discharge side of the rad (mine is in the lower rad hose). This will allow the rad to do its job and then only when needed will the fans come on.
If you install the sensor/switch in the thermostat housing (or anywhere in the intake manifold) you will be reading the engine temp before the rad gets a chance to cool it. If I am out on the highway cruising my fans will not come on until I slow down in traffic or stop. That has been well over an hour on a few occasions. That is because the air flowing through the rad cools the coolant enough that the fan switch after the rad does not get triggered. Basically only running the fans when its needed.
A sensor or fan trigger switch in T-stat housing or intake will trigger fans when engine gets up to the switch temp (depending on T-stat), thus running the fans when they may not be needed. Remember with the fans you are trying to cool coolant, not the engine. That's the coolants job.
Just looked at the switch/controller you are thinking of. Nice simple system but I do not seem to see amp rating for relay. With the Contour/Mystique/Cougar dual fans you will definitely want the 70A OEM sized relays to be sure all is good.
Was thinking, if needed you could use that controller to trigger the 70A Ford relay and power the low speed fans (12V power through the thermo resistor, then to the 2 fans). You could wire the high speed system through a toggle switch and a second 70A relay as a back up (I have never had high speed kick in unless I turned it on via toggle).
Was thinking, if needed you could use that controller to trigger the 70A Ford relay and power the low speed fans (12V power through the thermo resistor, then to the 2 fans). You could wire the high speed system through a toggle switch and a second 70A relay as a back up (I have never had high speed kick in unless I turned it on via toggle).
Didnt get grab the OEM relays. Should have.
Ya i agree. If the fans run at 20-22+ amp each. But i bought a 40 amp relay like that misinforming article lol. Figured i didnt understand something. Maybe i can run a 40a relay on each fan, and splice the temp wire and run it to both relays?
I'll just get a 70a relay. Thanks.
Ya i agree. If the fans run at 20-22+ amp each. But i bought a 40 amp relay like that misinforming article lol. Figured i didnt understand something. Maybe i can run a 40a relay on each fan, and splice the temp wire and run it to both relays?
I'll just get a 70a relay. Thanks.
So to best explain the factory Contour wiring let's start with a pic...
So first off, this pic is upside down. The plug shown at the lower left is found at the top of the rad on the factory set up. There are 2 wires (4 gauge each I believe) coming to this plug. The plug connects via a loomed pair of wires directly to the 12V outputs of the high and low speed relays.
The relays share power from a single 60A fuse that gets its power directly from the + terminal on the battery.
Middle fuse of the 3 in the top left of fuse box image shown (the 3 fuses are 80A, 60A, 60A). The 2 dark relays in the bottom left of image are the 70A relays, yellow one is part of the Contour A/C system. I actually removed the left half of the fuse box and installed in my Mustang.
So, how does low speed work. 12V power from low speed relay goes through plug mentioned above and runs directly to the thermo resistor shown in upper right of first pic (it is actually located driver side bottom corner in the car). The output of the thermo resistor goes to a splice/junction of the high speed power feed and the positives from the 2 motors. If memory serves it is located on the right side of the pic about 8" up from the thermo resistor (the shiny taped section).
The motor grounds are wired to another splice/junction, this time on the left side of the pic, again about the middle and again the shiny taped section. The single black wire exiting the pic near the top left is the ground to chassis for the motors.
With this simple wiring all that is needed is a high and low speed trigger. This can be done with one of many OEM fan switches(various manufacturers - I used VW/Audi unit), with aftermarket controllers or simple toggle switches.
What I suggested above was if you picked up the Hayden unit you listed, that it control the low speed fans (it shows a turn on temp of 185* which should work nicely). As a back up, I would wire the high speed relay to a toggle, just in case. I suspect you may never need it, but its good insurance.
So first off, this pic is upside down. The plug shown at the lower left is found at the top of the rad on the factory set up. There are 2 wires (4 gauge each I believe) coming to this plug. The plug connects via a loomed pair of wires directly to the 12V outputs of the high and low speed relays.
The relays share power from a single 60A fuse that gets its power directly from the + terminal on the battery.
Middle fuse of the 3 in the top left of fuse box image shown (the 3 fuses are 80A, 60A, 60A). The 2 dark relays in the bottom left of image are the 70A relays, yellow one is part of the Contour A/C system. I actually removed the left half of the fuse box and installed in my Mustang.
So, how does low speed work. 12V power from low speed relay goes through plug mentioned above and runs directly to the thermo resistor shown in upper right of first pic (it is actually located driver side bottom corner in the car). The output of the thermo resistor goes to a splice/junction of the high speed power feed and the positives from the 2 motors. If memory serves it is located on the right side of the pic about 8" up from the thermo resistor (the shiny taped section).
The motor grounds are wired to another splice/junction, this time on the left side of the pic, again about the middle and again the shiny taped section. The single black wire exiting the pic near the top left is the ground to chassis for the motors.
With this simple wiring all that is needed is a high and low speed trigger. This can be done with one of many OEM fan switches(various manufacturers - I used VW/Audi unit), with aftermarket controllers or simple toggle switches.
What I suggested above was if you picked up the Hayden unit you listed, that it control the low speed fans (it shows a turn on temp of 185* which should work nicely). As a back up, I would wire the high speed relay to a toggle, just in case. I suspect you may never need it, but its good insurance.
Yes, that's exactly what I do. Use the controller setup to activate a larger relay.
I've been using this Bosch 75A relay in my car for about 20 years. It's been ultra reliable with my 94-95 fan