Help me out here guys because I'm at a loss. I just installed a brand new LS1 Fan assembly by dorman part # 620-634 and these fans barely move any air compared to the Taurus fan I had on. The fan couldnt get the coolant temp at 180 (which is the T stat temp) last night in 78 degree ambient air with the AC on. This is something the Taurus fan had absolutely no problem doing.

Reason for the "upgrade" was because the Taurus fan couldnt keep it cool with the AC on in 100+ degree stop and go traffic. Anything below 95 was fine.

I wired these fans to 2 relays. A single 4 gauge wire to a distribution block then 2-10 gauge feeds to each relay. Bypassing all the relay and going straight to 12 volts doesn't make a difference in fan performance. Am I missing something here?

 

Are they wired backwards?

 

Probably dorman using cheap, generic "Chinese" made motors with unknown specs.

 

Nope, they are rotating counter clockwise and blowing towards the engine. If you take a paper towel it will stick to the condenser when they are on.

 

This could be true but how would I know? These things are quiet. Reminds me exactly of the stock single fan that was in the car. Barely moves any air and quiet as hell. The Taurus fan sounds like a jet.

 

Too quiet equals too little air pushed thru.If the fan casings have no markings as to make, model &/or country of origin.That's not a good sign in my book.
Another, fans blades w/ a poor design wont pull/push enough air either, so that's another unknown issue

 

Are the Dorman fans mounted to a panel that covers back face of the radiator?

 

I just wouldn't think that would be the issue with a brand new dorman assembly. These things are supposed to be godsend. 10,000 CFM are something like that.

You mean the shroud? Yes. 98% of the radiator is covered by the shroud.

 

Just got off the phone with dorman. These fans are only rated at 1150 CFM per fan. That's 2300 CFM total. That is was below what the OEM LS1 fans supposedly flow of 10k. Switched back to the Taurus fan, problem solved.

 

10,000 cfm rating for the LS1 fan assembly is WAAAY exaggerated there are no 12v automotive fans that will pull even half that,~3500 cfm seems to be about the upper limit for 12v,~16" dia.,single electric fans and that is about what a 3.8 Taurus fan is reconed to pull.