Heavy Towing: Electric fans or clutch fan?

[Aruba1]

I just been doing some research and I came to this site to ask a question if I should install a clutch fan on my 5.3L 1972 C30 as some people claim that electric fans will NEVER be able to move as much air as a clutch fan.

I am not too concerned with horsepower. IN my case I have a lot of issues with high temperature in traffic or when towing up a hill. I would like to go with clutch fan to fix this issue. The other option is get someone to tune my PCM ($250) to get the fans to come on earlier, stay on longer and add some more changes to take advantage of my exhaust system (headers, flowmasters, etc), cold air intake, 5 speed manual (versus the current automatic tune), 4.10 rear differential, etc.

Being my cooling system is most important to me, which one should I go with? Is it true that clutch fan move a lot more air than electrics?Some people claim 9,500 CFM at 1,800 rpm, does this sound right? Thanks

[mongocanfly]

I've got the same setup you have but with a 6.0...my dual electric fans move a ton of air..I don't know how they compare to a clutch fan but I don't see a clutch moving any more than the electrics..my first fan kicks in at 175 second at 185...it will sit there all day at those temps no matter what..traffic, 95 degree days, hauling my tractor and equipment (usually around 9500#)..no matter..it sits there at 180-185......what kinda temps are you seeing? I know the LS engines are designed to run hotter temps but the tuners set mine up this way and it works good..

[Aruba1]

Hmmm, that is nice you had yours tuned. Mine is not. Seems like my first fan kicks in at 185-195 on low and then it kick on high at 205. Around 210 both kicks in at high, which is extremely nerve wrecking to me. Around traffic I see 200-205, with or without tow. Who did your tune and how much did you pay?

I have a handheld tuner but since my PCM has some tune files that were not completely deleted my handheld is not compatible.

[mongocanfly]

I don't think 205 is anything to worry about..my new z71 runs hotter than that...I know it nerve racking but keep in mind these engines are designed to run hotter...even if mine doesn't...I had mine tuned on a dyno by a guy up close to huntsville..you shouldn't have any trouble finding somebody around b-ham that does the same thing...the guy I bought my engine from unlocked ecm and set the fan temps...after I got it all together and driving I then had it dyno tuned...well worth the money..first pull it was getting about 265hp..when he finished it had 344hp..he said he could turn it up more but I told him that's good enough..he charged $300..I definitely recommend you get it on a dyno..

[mongocanfly]

This is the guy that did my dyno tune.http://www.culverautospecialties.com/

[dec010974]

Hello Aruba1. I hope all is well with your LSx Swap. I don't know of this means anything to you but in my 1971 c10, my pcm was programmed with the fan #1 to turn on at 195 degrees and fan #2 at 205. In Miami, Florida heat, my fans rarely rarely came on in stop and go traffic. LSx can run hotter temps. They are not your regular SBC or BBC.

[dec010974]

BTW, I have completed 3 lsx swaps of my own and have helped most of my friends and I always run electric fans.

[68c10airstream]

Aruba1, Father in law ordered a 87 c20 5.7 700r4 new with 4.56 gear. First year tbi, pulled a huge 5th wheel trailer through the mountains after i installed a big hayden trans cooler. He said in the hills the clutch fan would roar for a while, cool down, stop roar, and repeat. Finally sold the truck with 150k on it with original trans and engine.

My 68 c10 5.3 4l65e swap has a fan clutch and all attachments from a 2001 junkyard pull. I installed the 2001 suburban hd radiator (modified core support side to fit it) 68 fan shroud 2001 fan clutch. I have pulled a small trailer (3,000 lbs) in 100 degree heat and never heard the fan clutch roar and no overheating. I believe it got to 215 degrees. I'm kinda old school and like the looks of a clutch fan and shroud.

[72MARIO]

I used the stock mechanical fan on my LQ4 swap just for reliability . Towing this summer tempatures reached 220 before the mechanical fan would engage on the hwy and 228 from a cold start sitting in traffic.

I am removing the mechanical fan and installing the grand Cherokee fan I had in previous with the old 327.

The reason I went mechanical is because I wanted cooling with ac on and electric fan off at road speed.I couldn't figure out how to accomplish this.

I have now set fan one on at 198 off at 190 and fan 2 on at 32 off at 320. I use the grounds to control 2 relays one for engine cooling fan and two for a/c I use the compressor clutch power to trigger the relay

I haven't driven it like this yet but I should work well.

[Overdriven]

The 4.8 in the 2010 Express van I drive for work is 210 all day long. Its easier to get less tailpipe emissions with the engine running hotter.

If it was me I'd make sure the thermostat is what you want and get the ecu tuned. Even totally stock there's usually about 30hp on the table with lots of gains across the whole curve. Have them set the fans to what you want at the same time and enjoy.

[Aruba1]

Thank you very much for everyone input. I also considered a group switch as it would come in very handy and by demand. I know that the LSX engine run hotter but it's really nerve wrecking when I know my fans take a while before they kick in and the temperature is climbing. I don't know, I may just have someone (Huntsville or in Odenville) to do some tuning and also have the fans kicking in earlier.

[MalibuSSwagon]

I'm running 95 Ford Windstar dual fans controlled by the PCM. Running same radiator and fans as I was when the truck had a TPI SBC, fans rarely kick on even when I was towing with the 5.3L, they would kick on all the time with the SBC. These fans move alot of air and cool the engine down quick. Also they are nearly a bolt on, little mods needed but they work great.