I'm going to be swapping my stock single radiator fan out for a thirdgen dual fan setup. I wanted to know if the stock relay by the battery can sufficiently power both fans if it is hooked straight to battery +.

I know you're SUPPOSED to give each fan it's own relay but the single fan relay has been powering my rad fan AND a 650cfm transmission cooler fan for several years now without any problems so figured I'd ask.

 

Depends what the total current load is with both fans running is ( + some safety margin ) and what the stock relay is rated at. 30A ?

Where the supply comes from is irrelevant ; it is the current drawn through the relay contacts that determines if it will live
Shortening the supply path ( ie; wired direct to battery Pos ) only reduces voltage drop giving more power potential @ the relay

 

I'm aware of that. I'm going to wire them straight to the battery for clean, direct power instead of through that puny little wire coming off the positive cable. I was just curious what the amp draw of the fans are and what the stock relay is capable of holding up to.

Like I said, I have been running two fans off the stock relay for years without any fires or melted wires but of course that isn't going to mean anything if the rad fan draws 15 amps and the transmission cooler draws 8 through a 30 amp relay. Put two 15 amp fans on and bring the relay to it's limit and I will most likely run into trouble during the high current demand to initially get the fans spinning.

I am more than capable of doing this believe me. I fabbed up the relays and wiring for my HIDs and installed my own viper alarm. I also did all the electrical work for my buddies entire nitrous system and it works flawlessly. I take pride in my electrical work and no one comes near this car with a soldering iron except me. I just need to know the numbers of what I'm getting into. Since I am going to make both the fans come on/off at the same time it does not seem reasonable in terms of simplicity to use two separate relays. I might just scrap the stock relay and go with a high amp one.

 

A higher amp relay would probably be best, if not for running both at the same time, the initial amp draw when the fans start. Are you going to run both from the thermo switch in the block?

 

This is a TPI motor so the fans are ECM controlled via the CTS in the intake manifold. The ECM switches the relay coil ground to activate the fans and my custom tune is set to turn them on at 190 and off at 180.