Electric Fan

[Holland]

I want to ditch my mechanical fan and convert to electric. I read through threads about them for the M20 but I still really don't know what I should get. I assume a 16 inch but that's about all I know. I have a stock thermostat which opens at I have no idea what fucking temp, stock temp sensor as well. I plan on ditching my A/C since it never worked anyway so I would probably be ditching my aux fan as well. I live in AZ so it hits around 90 or so in the summer. I don't know shit about fans so some input would be great, plus I don't really know if the m10's needs are the same as an m20.

[decay]

SPAL slimline from summit/jeg's and $8 fan mounting kit from kragen's.

if you're fucking crazy enough to ditch your AC in AZ (i know how it is... mine didn't work while i lived in scottsdale, but FAWK that was miserable), then use the wiring for the stock aux fan. nice thing about that is the AC button then serves to turn on your fan... works on an OEMish kinda level, you're just using the "snowflake" button to cool your engine rather than yourself :) you may have to switch to a higher-rated fuse like i did (but i used a volvo/E36 fan; same may not apply for the SPAL).

if you're already ditching the AC equipment, and thus taking the front body pieces apart, i would absolutely get a pusher fan and mount it fore of the radiator. it is REALLY nice having extra room to work between engine & radiator without taking anything apart.

on the M42 you can swap in the temp sensor for the E36 and it'll turn on at the halfway mark... don't know if there's a similar part for M10/M20, though. if you can't find anything, then just keep your eye on the temp gauge and turn it on if you see it go over halfway.

[Holland]

Room isn't really an issue seeing that I still have a lot with the mechanical fan. Correct me if I'm wrong but I'm under the impression that a puller fan is more efficient than a pusher. Also if I wire it to my aux fan wiring can I have it turn on automatically and have a manual switch (Like the one you mentioned) in case it doesn't turn on when I need it to?

[Holland]

bumpkthxbai.

[decay]

Room isn't really an issue seeing that I still have a lot with the mechanical fan. Correct me if I'm wrong but I'm under the impression that a puller fan is more efficient than a pusher. Also if I wire it to my aux fan wiring can I have it turn on automatically and have a manual switch (Like the one you mentioned) in case it doesn't turn on when I need it to?

re: room: think about it, it's pretty nice-



and i can't think of a reason why having the fan in back of the radiator would be any better than in front.

what i can tell you from direct observation is that after doing this conversion, the car settles in at about 3/8ths rather than 1/2 after warmup... but that may not be down to the fan because i made changes to the valance, lip, and shroud to make a nice big air scoop at the same time:


anyway as far as cooling behavior goes, the car has only gone above the halfway mark once, when i was stuck in traffic on the way out of town. pushing the AC button immediately brought it back down to below the halfway mark... the e36/volvo fan moves a lot of air.

and yes, that is what i was saying; the aux fan circuit activates at the 3/4 mark on the temp gauge and also when you push the AC button. either condition will turn it on. but you may want to look into a sensor that will turn it on at a lower temp.

[Holland]

I'm bumping this thread. I have a Spal fan now, with the mounting and relay kit. I understand how to wire it up for the most part but how would I wire it up to the AC switch as previously mentioned. The relay kit only has a ground for an external switch not a power wire.

[mlytle64]

you don't need the relay kit. all you have to do is wire the fan to the same plug teh stock aux fan was plugged into. it then works using the stock power, relay, fuse, temp switch and a/c switch. doesn't get much easier than that!

[milotrain]

You might want to wire a switch to jumper the Aux fan relay. In the case of the E21 the Aux fan only comes on when the engine get's really hot and you want it to come on earlier because it's taking the place of the engine driven fan.

I don't know if this is possible or even a good idea but you could build a separate relay circuit that is switched from the dashboard and runs say 8v or 6v to the fan so that it spins slower than normal (because you might not need full spin to cool the engine). Then if the temp sensor kicks in you can run the fan at over-voltage if you need to (by combining the aux fan 12v circuit with the switched 6v), because it's really hot and you're sitting in traffic. Might burn the fan out though.

[Holland]

you don't need the relay kit. all you have to do is wire the fan to the same plug teh stock aux fan was plugged into. it then works using the stock power, relay, fuse, temp switch and a/c switch. doesn't get much easier than that!

Would it even come on using the factory wiring though? My old aux fan never kicked on when the car was running hot in the past.

[milotrain]

It should come on. Just really late in the game. Like red zone late not 3/4 late. That's why I'd run a jumper switch.

[Holland]

It should come on. Just really late in the game. Like red zone late not 3/4 late. That's why I'd run a jumper switch.

I see, I really don't like the idea of burning out my new Spal fan though. Are any of the 02 or E21 guys running lower temp sensors?

[mlytle64]

yes, there are lower temp switches available.

and if you have (had) a/c, don't need jumper switch. you can turn fan on by turning a/c on.

[Holland]

I gutted the a/c already. I want to turn the fan on manually when I need to but I would like to have it on auto as well in case I'm not paying attention for whatever reason. So correct me if I'm wrong but all I would need is a lower temp sensor to fix that problem? What degree sensor would I need?