Rx7 Project: Electric Fan
Most people want to know which fan to buy, so I'll start by giving the who, what, when, and where on the best electric fan to use in an '79-'91 Mazda Rx7:
Flex-a-Lite Model #150 (Black Magic Fan)
Stats on the fan:
moves 2800 cfm
15" diameter blades
will cool an engine producing up to 260 hp
adjustable thermostat from 180-240 degrees
measures 18" x 16 1/8" x 4"
Before I bought a fan, I did a great deal of research. I called tons of manufacturers and distributors and spoke to anyone I could find that was running an aftermarket electric fan. I even found a few Rx7 owners running them. Here is the digested version of my findings:
The Victoria British fan is crap
Pulling OEM fans from other cars (Buick, Ford, Chevy, etc.) is a major waste of time. Fans designed for puny 4 cylinder engines will not cool a rotary!
The Flex-a-lite M#150 fan pulls more cfm than any other fan I could find... even the dual fans!
Before I start showing pics or go into the installation process, let me tell you what I think of the fan so far. I've been running it for about 4 months now. I love it. The engine temp stays exactly where it did with the stock fan. It has kept the engine cool through hard driving and major traffic jams, with or without the A/C on. An man does it pull some air! With the engine and the fan running, you can put your hand on the ground in front of the rear wheel and feel the warm engine air that the fan is blowing out of there (and yes, I have both lower engine compartment covers in place). The thermostat is easy to adjust. I just cranked it all the way up, started the engine and let it get to normal operating temp (about 1/4 on the gauge) and then turned the thermostat down until the fan kicked in. Also, I was worried about the fan pulling an excessive amount of amperage from the charging system, especially with the slightly undersized dual alternator pully that I'm running. There is a slight drop on the voltage meter when the fan kicks in, but it still stays well above the 12v minimum.
Now to the installation. The one thing I changed was the mounting hardware. The brackets than came with the fan are very large and cumbersome. They can be used, but they would require some relocation of the battery. Instead of using their brackets, I went down to the local hardware store (Ace is the place.....) and spent about $5.00 on some hardware. I bought a few eye-bolts, washers, nylock nuts, etc. Instead of wasting time (and confusing you) by trying to explain it in words, just take a look at the pics:
Click on any pic to see the full-size image
As you can see, I drilled some small holes in the radiator frame and mounted the ends of the eye-bolts in them. These can be used to pull the fan shroud up tight to the radiator. I used washers and bolts on the included threaded rods to secure the fan's position. I used washers anywhere that I could (they're cheap) and nylock nuts in order to prevent any chance of them vibrating loose. It worked out great. They take up much less space and look better than the provided brackets. I had to leave the lower-left mount off (see above pics) in order to keep from moving the battery, but three mounts are plenty to keep the fan in place.
The wiring is pretty simple. You have one wire that goes to a switched, low-amp power source (something that the ignition switch turns on) to tell the fan when the car is running. This will keep the fan from kicking on when you're away from the car. If you want the fan to function when you are away from the car, just hook the lead up to a source that is always hot. The second wire goes to a high-amp, non-switched power source... this is where the fan gets its power. I put an eyelet on that wire and ran it to the alternator, I used the included breaker and mounted it on the inside of the driver's side fender (I would highly suggest you use the breaker/fuse for extra safety). A third wire goes to a ground, and a fourth wire splices into the A/C wire so that the fan will kick in whenever the A/C is in use (to pull air through the A/C condenser). You can also hook up a manual switch if you desire, but it is not needed. I routed all of the wiring underneath and behind the battery box where it is quite out of sight.
The wiring is not hard, but don't try it if you aren't familiar/experienced with such things. You could really mess up your car. Someone with professional experience in installing radio equipment should be able to do it (unless they're an idiot). Just find someone who knows what they are doing or you might wind up with your car on fire.
That about covers it. Here are some pics of the installed fan. Please excuse the filthy engine compartment (I cleaned it a few days later, I swear!).
Oh, I almost forgot. Power gains. I'm sure you want to know about that ;)
I can tell quite a bit of extra power in first gear under wide-open-throttle. That's because the old clutch fan isn't having to spin up from idle to 7000 rpm. I can tell a small difference in power in other gears. Overall, the engine is much more responsive to throttle input. If you're looking for a big power increase, I wouldn't rush out and buy an electric fan. However, if your fan clutch is bad and you're going to have to spend money anyway, I'd go with the electric fan.
I've been using this fan for quite a while now (about a year I'd guess). The only problem I've had is that the thermostat in the fan died and the fan just wanted to stay on all the time. This didn't cause a problem and I was able to take my time in replacing the fan's thermostat. The replacement part cost about $25 from Flex-A-Lite.
Also, I've been caught in several interstate traffic jams in this 100-105 degree weather that we're having right now. The temperature gauge has not moved a bit! Also, I'd bet the air temp was much higher on the interstate (asphalt, other cars, etc.).
DISCLAIMER: If you perform the modification described above and something bad happens (engine explodes, car catches on fire, dog dies) then I accept no responsibility. You perform these modifications at your own risk. I'm just trying to share my experience with others trying to make the same modification.
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