For you guys burnin up lil 30/40 amp relays..

Look into Motorcycle starter solinoids.
They can handle all the amps your fans will ask for and more.
If you go to a cycle salvage yard. look at the late 70's - 80's model bikes.
The solinoids are metal housed and are weather proof.
This is what I use on ALL my fan installs. Never had one fail.

Or you could go to salvage yard and look into the early 90's model camero's the elec fan relay harness they use is VERY robust and uses 2 60amp relays.
Now they are wired alil diff than what we need on our trucks, but can be adapted very easy.
If I wasnt stuck on starter noids, This would be the setup I would use. I used this on my S10 projects for years before switching over to starter noids.
Grab one harness per fan. This gives you 2 relays per fan, Wire them up so they Both click on for each fan, thus you have a redundent back up for your relays..
Just beshure to snag as many of the relays from the salvage yard as you can. these relays are expensive to replace if bought new from GM.

 

For the guys that made there own harness, what is the part number to the relay your using? I looked at the schematics and it seems pretty simple to make one I just want to use the right relays so I don't have any problems.

 

personally i wanna say i love my e-fans. i made my own harness and the only problem was a relay decided to not work after a week or so. never noticed it till dad pointed it out. so 1 fan was able to cool my truck for around 2 weeks without a problem. i did replace both relays with new waterproof ones and there still working a month later.


i used this for on fan: http://www.jegs.com/i/Derale/259/167...oductId=758411

relays that i used to replace were these: http://www.parts-express.com/pe/show...number=330-079

but you could upgrad to ether of these
50amp: http://www.parts-express.com/pe/show...number=075-138
70amp:http://www.parts-express.com/pe/show...number=075-140

 

I always used standard Bosch relays. The only time I had a problem (one of them blew) was because of a bad connection. I re-crimped and soldered and no problems from there out.

 

I just use the $4 ones from Advanced Auto. Never had a problem.


That harness is easy to build.. just follow the lines.

 

Where are you guys fusing your harnesses? Some people fuse leads to the fan and some fuse the main power leads to the relays. I was planning on fusing the always-hot leads going to the relays and calling it good. Will that be enough?

Also is there a need to protect the leads going to the ECM (Im building a 2 wire harness)? fuse/diode?

 

The schematics in post 19 and 20 show you where you should put the fuses.

 

I just built my own harness last week. used 10ga for the main power and the main ground, and 12 ga for all other connections. Also I'm using 30/40a relays.

 

Does anyone know how many amps each fan draws at high speed? I've seen somewhere, maybe ls1tech where it was said the total amp draw for dual fans was 40 amps. That would be 20 per fan. Does that sound right?

 

I have my mechanical fan and shroud for sale if anyone wants to give up on their efans