A lot of people want to convert to an electric fan for their cars, either because their stock "clutch-type fan" is dead, to save energy, or to free up space in the engine bay.
Some people say that electric fans do not save energy, the reason being that you lose energy by converting it from kinetic energy into electricity, then back into kinetic energy, unlike the stock fan that is just belt driven without the conversions. This would be true, but only if the electric fan ran at all times. It saves energy by only turning on when it is needed. This is why most modern cars have electric fans. The engine does less work, so you get a little more power and slightly better fuel economy.
I removed my stock clutch fan in my Mazda RX-7 and replaced it with the stock twin fans out of a first gen (Mark I, from the eighties) Toyota MR2, and I did it for about $20. The reasons were simple. The most important reason I did this was that the stock clutch was dead, and a new one costs more then the MR2 fans at a junkyard. I also like having all that room in the engine bay, making it easier to change belts and observe engine operating conditions.
What electric fan should I use?
You can use almost any electric fan you'd like, I would recommend grabbing the twin fans out of a Mark II MR2 if you can, because they are less likely to be rusted out then the Mark I fans, and they look much nicer. The parts are interchangeable, and the motors have been upgraded. In fact, if you have dead Mark I fans, you can get rebuilt motors for the Mark II and turn the old motors in for the core charge.
Installation
This install is on a 1990 Mazda RX-7 Convertible with A/C. Your setup will vary, and you can find a different set of fans (or fan) from another junkyard car, just make sure it covers the radiator well and works with your shrouding.
The dual MR2 fan shrouds are made of metal and fit almost perfectly with a little bending. As anyone who has ever owned an Mark I MR2 knows, everything metal on the car rusts out, so I had to wire wheel and then paint these fans (I did too quick a job on the shrouds, in my opinion). Then I painted the (previously off white) fans black with some KRYLON PlastiCote. I really like the way they came out (scroll down for pictures).
I put regular house weather stripping along the edge of the fan and then set it on my radiator. I cut a few lengths of coat hanger up and then bent them in to create the brackets to hold the fans in place. If you want it to look nicer, you can use zip ties through the top of the radiator. Next, I bent the metal of the fan shroud flat around where the coolant hoses are run (I don't like the idea of my soft rubber hoses touching a vibrating metal fan shroud)
I tested each fan for polarity by applying battery voltage, and then set them to pull air through the radiator. This is important, you don't want the fans fighting incoming air. I then ran the ground wire to the chassis right next to the fans. I used all 8 gauge wire, this is important, you don't want to use too small a wire or it will heat up, and might even cause major issues. The positive wire went to a relay.
Controlling the Fan
Now, you can have the relay powered by a switch that you manually flip (that's no fun, and kinda dangerous if you forget to flip the switch), a thermoswitch (sounds good to me) or an aftermarket ECU (thats what I did). If you don't use an ECU, you can use an aftermarket temperature switch, or just build your own.
I have the The MegaSquirt ECU set to switch on the relay on whenever it sees the engine temperature go OVER 200F (210F is the maximum acceptable operating temperature) and switch it off around 184F.
The temperatures you set will be dependant on what car you install your fans on, and what thermostat you are running. If you're in doubt, just set it to 200F.
Results
When the fans come on, it's insane how fast they cool down the radiator. You can put your hand behind the airstream and FEEL the temperature drop in the air coming off. The coolant sensor input to my ECU hesitates a little, (The waterpump has to circulate the cool water, then the sensor has to catch up) then the display shows the temperature drops 20 degrees almost instantly!
These fans are much quieter then the Black Magic or Flex-a-Lite fans that I have heard. The fans do not over tax my stock alternator either.
Test fitting the fans:
Bending to clear the lower radiator hose:
You will have to bend it on top for the upper radiator hose too.
I would post better pictures, but a bit after I installed these fans, the car was stolen! I hope this writeup has been helpful for you, feel free to ask questions in the comments section!
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2 comments:
Failocaust:
Clutch fans will activate only as needed if the clutch is operating properly.
Clutch has viscous silicon oil in it. When it heats up, it thickens and the fan is coupled to the water pump pulley.
When it's cool, the oil thins out and the fan freewheels
You can not find a set of electric fans to cool a 7.3L Diesel. None move enough air.
Sure, but not all cars come with clutch fans, it's usually just a belt driven fan. And most people who read this, I'm willing to bet have aging clutch fans like I did, where it would be cheaper to pop electric fans in and clean up the engine bay, then to replace the stock clutch fan every time it goes out. :)
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