My dad wanted me to find out if the single electric fan from his '91 RS will be sufficient for his LS1 swap. I used the LS1 dual electric fans on my swap and they work great. Is having only one fan going to be a bad thing? I suggested the idea of LS1 fans for his car but he wants to see what you guys think about the single fan.

 

LS1 dual fans if you have them wired up the factory LS1 way.

 

Mine cools fine with the stock single fan

 

Amount of fans doesn't really matter, just how much air they push. So with that said I'd say the LS fan throws more CFM than an 91RS fan does, but don't quote me, just figure due to the new technology.

But I'd agree with saying you might as well save time and keep it simple. Get another set of LS fans and plug and play. Have fun.

 

i had a 92 rs single fan. cooled the car pretty good. there are people running the single fan with the ls swap. but when i put the ls fans on i can tell you that i have no problems whatsoever in cooling mine. they put out way more. a good cleaned rad and not running it real hard with upped timing and a/c i say it will work. but if it is going to be a perf engine and a/c go with ls1 fans. they are cheap enough. heck from 1993 to 2002 fans will work.

 

I have the stock single RS fan cooling my LS2 and it runs very cool, never climbs anywhere near 200 even when it's just sitting there idling for a while

 

Stock single 87 fan idling away in rush hour Toronto traffic ( You probably have no idea how bad traffic is here ) and we have HEAT in the summer. Mine never gets above 180 it runs shockingly cool

 

I guess the dilemna I saw with the LS fans is going from single fan wiring to dual fan wiring... But if we went that route I'm sure Jon could do somethin' for me

 

Dual fan wiring is as simple as running the single fan wire to a relay, and from that, running a wire to both fans. Both fans on and off from one signal.

If you wanted to get fancy, you could do a stock-style configuration where the AC compressor signal can also trigger the 2nd fan, but that's mostly unnecessary; might as well have both fans on any time the ECU calls for a fan.

 

Best to use 2 relays, 1 for each fan. One signal wire to each relay then each relay to its own fan.

 

Other than eliminating a single point of failure (i.e. at least one fan will still work if you nuke a relay), it doesn't offer any advantage, and complicates wiring. I generally find relays to be reliable enough that it's not really an issue, but if you feel it is, it's easier to stash a spare somewhere, or use the same one that you're also using in some non-critical application somewhere else on the car.

 

The reason I see for using a relay for each fan is to avoid over-current of one relay driving two fans.

 

if you are really worried about a relay going out then use this one. we use this one on our industrial equipment that handles a lot of abuse.

http://www.wiringproducts.com/contents/en-us/p71.html

 

You already did it once, no reason you cant handle it again

I personally think the AC override that GM puts in the fan circuits is silly. Set the turn on temp in the PCM and be done with it. Add a thermal switch as a redundant backup in case the PCM for some reason does not engage the fans. Fan draw isnt excessive, nor is it constant. Making the circuits overly complex like the multiple relays to set single speed fans to "variable speeds", override conditions, non symetric circuits etc seem pointless in the end. If X fan doesnt cool the engine enough, use a bigger one. If fan Y pulls to much current, use a bigger alt. Ive found out the hard way the simplest method generally is the best method. The LSx PCM has two fan relays controls. Set the turn on temp for each and forget about it

 

Agreed. The current draw of a couple fans is well within the capabilities of a Bosch 30 amp relay.

 

Thats the exact setup Im using and when the fans kicks in, it takes about 15 seconds to cool, then they turn off. They are both powered thru dual 30 amps relays.

 

I'd still stick with a relay per fan.

 

This is exactly how I want to hook up my dual fan setup when my shroud/fans arrive in a few days. I plan on using two factory relays, one of which I have from my single fan. I want to get a factory 4 pin connector and another factory relay, mount it on the other side of the metal where the first relay is. I'll run another fused power wire to the new relay and another ground to the chassis. My question is in the picture, can I splice off the the wires labeled as "These Two" assuming those are the triggers from the ecm? I just want to make sure it wont put too much stress on the circuit and blow it out causing my ecm to not be able to work the fans at all. Is there another way to trigger the second relay or is what I plan ok. I'm definitely using two relays so it's just how to trigger the second one. When done it will look basically like two factory wired single fan setups in one car.

 

i am running the stock single fan from my '85 iroc with my LS376 / 480 conversion... no trouble

 

Ok but that doesn't really answer my question about triggering a second relay from the original trigger signal.

 

that one trigger wire (should be ground) will control 2 relays with no problems.

 

Ok but which wire? The one I have in the picture marked as ground goes directly from the fan to the chassis. So, you're saying one of the two I have marked as "these two" is a ground going to the relay right? I just have determine which one and tap off that one?

 

The pull in coil in these relays draws very little current. The signal wire should handle both with no problem.

 

one is going to be ignition 12V and the other is going to be ground.
The Ground is the ECM control wire, so that is the one you will use on both relays (as well as the ignition 12V)

 

Thanks very much. I just ordered this from tpiparts.net so I'll tap both those two wires then.
Going to AZ to get the factory style relay and I'll be good to go.