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    Results 1 to 8 of 8
    1. #1
      Join Date
      Aug 2005
      Location
      Las Vegas, Nv
      Posts
      114

      Electric fans, hi/lo or on together?

      Hey all, I'm finally putting a few miles on my Cutlass and the other day it was running a bit warm for my liking (220 IIRC). Granted it was 100 degrees out and I had the AC cranked. I knew the cooling system was something I'd probably have to tweak and one thing that crossed my mind are the fans. I'm running 4th gen f-body fans along with a Dakota Digital fan controller and the fans are wired so that both are turned on/off at the same time. The car has a 175amp Powermaster alternator and even at idle there is barely any voltage drop when they kick on. The controller has the ability to do hi/lo so each fan can be controlled independently though it's not a pwm style so when the fans kick on, they are on full blast. Just curious about everyone's thoughts on fan setup, whether to leave as is or go the hi/lo route since I have that ability. Thanks, James
      '72 Cutlass - 370" LS2 topped w/a LSA blower

    2. #2
      Join Date
      Mar 2020
      Posts
      199
      The F-body fans were originally designed to run in series/parallel configuration so both ran at half speed on low.
      This is the ideal configuration as 1 on & 1 off may cause the air to short circuit from 1 fan to the other or also may allow a portion of the radiator to not receive any air flow.

      What temps are you turning them on at? You can effectively turn them off below the engine thermostat temp & enable low at about 10 deg above & high at 15 above.
      Also they should run anytime the AC is on to ensure flow through the condenser.

      If you were at 220, I would assume you already have both running at full speed... this would suggest you need more cooling than is available.

    3. #3
      Join Date
      Aug 2005
      Location
      Las Vegas, Nv
      Posts
      114
      Thanks for the reply! Currently the fans come on at 205, off at 200 and I'm running a factory LS1 thermostat (195 I believe). Once the fans come on they don't shut off lol At least not until I turn the car off, highs here will be close to 100 degrees til the first week or so of October. Also, rad is a factory LT1 4th gen F-bod unit. Since I have a power steering cooler, big trans cooler and a condenser all in front of that rad, the high ambient temps may be too much for it.
      '72 Cutlass - 370" LS2 topped w/a LSA blower

    4. #4
      Join Date
      Apr 2001
      Location
      The City of Fountains
      Posts
      15,971
      Country Flag: United States
      Quote Originally Posted by Chocolate Apocalypse View Post
      Thanks for the reply! Currently the fans come on at 205, off at 200 and I'm running a factory LS1 thermostat (195 I believe). Once the fans come on they don't shut off lol At least not until I turn the car off, highs here will be close to 100 degrees til the first week or so of October. Also, rad is a factory LT1 4th gen F-bod unit. Since I have a power steering cooler, big trans cooler and a condenser all in front of that rad, the high ambient temps may be too much for it.
      Stock LS thermostat is 187 degrees. The GM performance ECU kits turn the fans on at 21 and off at 205. You may not have enough radiator to run any cooler.

      Andrew
      1970 GTO Version 3.0
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      "You were the gun, your voice was the trigger, your bravery was the barrel, your eyes were the bullets." ~ Her

    5. #5
      Join Date
      Aug 2005
      Location
      Las Vegas, Nv
      Posts
      114
      Yeah, I'm starting to lean in that direction
      '72 Cutlass - 370" LS2 topped w/a LSA blower

    6. #6
      Join Date
      Jan 2006
      Posts
      385
      Country Flag: United States
      I've been running a mid-90's Ford Taurus fan for the last 10 years or so. Two speed. Moves a TON of air.

      180F thermostat, "Autozone" style plastic tank aluminum radiator, and stock water pump. Fan is controlled by EFI ECM.

      ~400 hp Gen1 small block.

      Only time the high speed ever comes on is in traffic in ~100F weather with the A/C on.

      Just proves you don't need high-dollar stuff for a robust cooling system.
      1971 Camaro
      GM HT383, MiniRam EFI, AFR heads
      "8-speed" trans (700R4 + Gear Vendors OD)

    7. #7
      Join Date
      Oct 2014
      Location
      DFW, Texas
      Posts
      422
      Country Flag: United States
      The way my ECU is set to run dual fans is a little wonky, so I end up powering both windings at the same time [high and low]. Not ideal, but it doesn't seem to be causing any problem.

      I do that to help ramp up the speed, sort of a poor man's pwm. I hit the low speed for 1s before the high speed hits, which reduces the massive current hit.
      1972 Plymouth 'Cuda - Not LS-swapped, 5.7L Hemi [MS3 Gold Box], T56 Magnum 6-speed - 'Cuda Build Page
      1976 Dodge D100 - Warlock
      2016 Subaru WRX - E30 Tune

    8. #8
      Join Date
      Aug 2005
      Location
      Las Vegas, Nv
      Posts
      114
      Quote Originally Posted by ULTM8Z View Post
      I've been running a mid-90's Ford Taurus fan for the last 10 years or so. Two speed. Moves a TON of air.



      180F thermostat, "Autozone" style plastic tank aluminum radiator, and stock water pump. Fan is controlled by EFI ECM.

      ~400 hp Gen1 small block.

      Only time the high speed ever comes on is in traffic in ~100F weather with the A/C on.

      Just proves you don't need high-dollar stuff for a robust cooling system.

      Yeah, I'm trying not to spend big bucks on mine, still some work to do before that.
      '72 Cutlass - 370" LS2 topped w/a LSA blower






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