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Discussion Starter · #1 ·
so i know the 05 up trucks had an electric fan option. i have a 2003 sierra with the 5.3 im trying to gather up everything i need to convert it to electric fans. however, the electric fan unit is over 600 dollars from advance auto parts!

is there a cheaper way to get this done with the factory style parts i dont wont to zip tie it to the truck and i dont want random wires running to it.

EDIT: rockauto has it for $373, thats a lil better. what else will i need to complete this? i think i may need the radiator from that year truck also?
and what about the harness?
 

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are ls1 efans better then the oem ones off 05+?
A fan is a fan, so no. They fit the older 27" radiator and that's about it. The 05-up fans only fit a 34" radiator.
The 05+ fans are bigger and move more air. I wouldn't trust the LS/LT1 fans on a truck that is used for towing much, but for a DD they are great, and much easier to come by. As mentioned the LS fans are easier to adapt to the 28" radiator that is more common in the 1/2 tons, the 05+ fans need the 34" radiator.

Measure your radiator, if you have the 34" find some 05+ fans, if you have the 28" you will be fine with the LS fans unless you feel like replacing the radiator as well, although it just drops right in. The blackbear harness and tune works just the same no matter LS or 05+.

The LS fans take some adapting to fit, but the 05+ fans bolt directly to the 34" radiator, went right on with no issues on my 01 2500HD. Most 1/2 tons have the 28" radiator, but some have the 34". I know my mom's Tahoe 5.3 4x4 tow package had the 34", when she wrecked it I snagged the radiator support complete with a radiator off another 5.3 Tahoe that had a 28" radiator. I reused her 34" radiator since it was undamaged and it dropped right in place of the 28".
 

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The 05+ fans are bigger and move more air. I wouldn't trust the LS/LT1 fans on a truck that is used for towing much, but for a DD they are great, and much easier to come by. As mentioned the LS fans are easier to adapt to the 28" radiator that is more common in the 1/2 tons, the 05+ fans need the 34" radiator.

Measure your radiator, if you have the 34" find some 05+ fans, if you have the 28" you will be fine with the LS fans unless you feel like replacing the radiator as well, although it just drops right in. The blackbear harness and tune works just the same no matter LS or 05+.

The LS fans take some adapting to fit, but the 05+ fans bolt directly to the 34" radiator, went right on with no issues on my 01 2500HD. Most 1/2 tons have the 28" radiator, but some have the 34". I know my mom's Tahoe 5.3 4x4 tow package had the 34", when she wrecked it I snagged the radiator support complete with a radiator off another 5.3 Tahoe that had a 28" radiator. I reused her 34" radiator since it was undamaged and it dropped right in place of the 28".
They should be fine. Many people have retrofitted the SHO Taurus/MkVIII 2 speed fan into obs trucks with a 5.7/7.4, and they more than adequately cool the engines at idle. I can't recall the specific CFM they pull on high speed, but it's similar to the 2-fan setup of LT/LS fans. That's assuming whoever takes time to install them does it properly with a shroud fitting the fan.
 

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I wouldnt trust anyones harness.. do a quick search on pt.net and see how many ppl have had their fans fail... mine have and so have many others... if your gunna do it get the wiring diagram and build your own harness and heat shrink everything and make sure its a nice tight/sealed harness...
 

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I just got some from another member, of course the harness is incorporated in the LS harness for the swap ;-P
 

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any gains? and if so what did you get from it?
Nothing. The factory clutch fan is already disengaged at cruising speed so there isn't any HP to be gained from it.

your truck won't sound like a 747 takin off when its hot outside.. That's the biggest plus for me but I have a clutch fan again haha
:jester: Instead of that you just have to listen to them roaring like hell at idle when they come on high.
 

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They should be fine. Many people have retrofitted the SHO Taurus/MkVIII 2 speed fan into obs trucks with a 5.7/7.4, and they more than adequately cool the engines at idle. I can't recall the specific CFM they pull on high speed, but it's similar to the 2-fan setup of LT/LS fans. That's assuming whoever takes time to install them does it properly with a shroud fitting the fan.
Read again, I said they would be fine for normal use, the Taurus fans are pretty popular as well mostly with Jeep guys. You are correct they more than adequately cool the engine at idle, the issue comes when you are actually putting a big sustained load on them, such as pulling a heavy trailer up a grade, above the 2500-3000 rpm you would be running the engine at sustained for a while depending on the grade, the electric fans even on high cannot come close to matching the air moved by the stock clutch fan which would still be locked at that point. I noticed my truck even having a harder time keeping the temps below 200 on hot days on the beach, where the clutch fan kept them at 190 (on the gauge).
I wouldnt trust anyones harness.. do a quick search on pt.net and see how many ppl have had their fans fail... mine have and so have many others... if your gunna do it get the wiring diagram and build your own harness and heat shrink everything and make sure its a nice tight/sealed harness...
Agreed, I've had quite a few problems with my Nelson harness, and have pretty much rebuilt it after it killed a few relays and burnt a few wires.
any gains? and if so what did you get from it?
Coming from a truck that already has a stock clutch fan, you will not see a whole lot as far as performance or gas mileage since the stock clutch fan disengages at cruising speeds anyway. You will notice less noise on hot startups and your AC will work much better at idle and in traffic. Almost too good in fact, I think the increased airflow at idle makes my compressor shut off too quickly, I believe the Efan trucks may have had a different size orifice in the lines. Now if you removed a direct drive fan from say an old SBC, you would see better gains in the performance area.
 

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I understand that Garrett, but it varies by situation. Obviously you can hear the clutch fans on semis roaring going up the grades on I26 at the Brevard fault when they're down to ~30mph at best going up that hill, but you'd think at some point that fan would be an impediment to airflow if it stays locked at higher speed. :think: Certainly they move more air over the radiator off idle than electric fans and that's where the advantage to a clutch fan is. When I was fighting my overheating issues that was always the quickest way to cool it down, IE - transmission in neutral and engine at 2K rpm with the fan fully engaged sitting still.

I've always wondered why more vehicles don't have electric clutch fans on them. Seems to be the best of both worlds. Prime efficiency at cruise since the clutch is completely disengaged vs a viscous clutch that will always have some parasitic drag and the superior airflow at low speeds when it's locked. Too bad the early ones that came on Trailblazers were prone to failure and left people with a bad view of them.
 

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Discussion Starter · #18 ·
so the main reason i was even considering doing this is because i like to take my truck to the track and was thinking it would free up some power. is this even worth doing? hell it may be worth doing just to get rid of the sound the clutch fan makes
 
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