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I had to modify some homemade brackets to make fans mount decently. Now I know that Summit carries some, so I will be ordering some. Also pay close attention to those little rubber flaps on fan shroud they help when on the highway.
I think my main problem is not enough cfm, then the flap material (to heavy duty), the air gaps, and lastly the top rad hose and maybe bottom.
Im ordering more cfm flow fans, bought some thinner rubber and foam for sealing edges. Ordering new steel flex hoses. If that doesn't do it I'll light it on fire. Lol
Timing is 10 initial 32 total. Engine is a 383 stroker, aluminum heads, air gap intake, holley 750 DP, cam is a 272/272, 10-1 comp flat top forged pistons, 1 3/4 headers to 3" stainless exhaust. Makes 365 RWHP on a mustang dyno.
I never had a cooling problem till I went to electric fans. So shroud and not enough cfm I believe is the main problem.
I copied the C5 shroud but put cutouts for highway flow. I'm going to block them off for now. See how that works out.
Last edited by 79C3Vette; Sep 4, 2024 at 12:23 AM.
Reason: Add info
Many of the aftermarket 'shallow' designed fan shrouds shown so far are basically inefficient even when used on lower powered SBC Vettes. Irrespective of the 'vent' flaps built-in that are 'supposed' to open-up and release cooling air that will have built-up in front of the radiator when the fans are inoperative. In all cases the shrouds pictured place the two small relatively low powered fans too close to the rear surface of the radiator..........result being when operating the fans are only really drawing cooling air through two corresponding sized circular areas of the radiator......and not the whole radiator surface (unlike a stock fan shroud that places the single fan further away from the radiator surface, creating a far more efficient plenum. Twin electric fans (as typically used in these applications) may 'stall', limiting air movement, whereas a 'working' OEM type clutch fan will never stall, use-up zero HP when 'idling' and shift far more air than most aftermarket electric fans. The real trick would be to fabricate a replacement shroud that encapsulate the fan blades tighter than stock shroud creating even better air movement.
Many of the aftermarket 'shallow' designed fan shrouds shown so far are basically inefficient even when used on lower powered SBC Vettes. Irrespective of the 'vent' flaps built-in that are 'supposed' to open-up and release cooling air that will have built-up in front of the radiator when the fans are inoperative. In all cases the shrouds pictured place the two small relatively low powered fans too close to the rear surface of the radiator..........result being when operating the fans are only really drawing cooling air through two corresponding sized circular areas of the radiator......and not the whole radiator surface (unlike a stock fan shroud that places the single fan further away from the radiator surface, creating a far more efficient plenum. Twin electric fans (as typically used in these applications) may 'stall', limiting air movement, whereas a 'working' OEM type clutch fan will never stall, use-up zero HP when 'idling' and shift far more air than most aftermarket electric fans. The real trick would be to fabricate a replacement shroud that encapsulate the fan blades tighter than stock shroud creating even better air movement.
I know its been beat to death but these work great as an option as well.
They are clones to the spal units dewitts sells and the units Be cool sells I use one on my c3 and they have more than enough cooling capability. typically only one fan runs in my setup. summit sells the mounting brackets. each fan draws about 14 amps. I'm in the process of upgrades and I havent reconnected my temp sensor in a few weeks. I took it to a car show this last weekend that was 50 mins away. I have 1 fan on an override switch so with that on the engine stayed cool on an 80 degree day and the drive. My thermostat coincidently must be stuck open because the engine stayed below 160 while the car was moving even though it has a 180 stat it did creep up while parked and depending on the fans and idleing for a while but again I only have one fan running until I swap engines.
I can only speak for myself here but as someone who actually tried both first hand, the stock setup didnt meet my goals even after completely rebuilding it with new rad, seals and clutch. it would cool but the temp would climb well over 200 degrees in traffic even with the 180 stat which I did not like.
YMMV but the electric fans arent running and draining power while my car is moving and I have the ability to easily modify when they do and dont kick on.
Now than im installing a fuel injection system with dual fan control it will automatically adjust idle when the fan (s) kick on and off which is nice also or if I decide to reinstall the AC.
I also had way more room in my engine bay to swap my a arms and do other work. I feel if clutch fans were truly superior GM and every other car manufacturer wouldnt spend more money on developing and installing an electric setup with true on and off capability and without the parasitic drag. I mean, does the c4,c5...c8 have any cooling issues with their electric fans?
Different folks, different strokes theres more than one way to accomplish a goal. We really dont need to beat this horse to death here again. I will agree if your car is overheating with a properly functioning stock clutch fan setup than there likely something else wrong and electric fans are not the solution.
Last edited by augiedoggy; Sep 4, 2024 at 10:15 AM.
You just solved your own problem : the electric fans/ shroud setup is inadequate. Go back to the clutch type fan and factory shroud, it can flow up to 3500 CFM when needed. And don't worry about the 5 Hp gain with electric fans, you can't use it anyway not with high engine coolant temps.
I think my main problem is not enough cfm, then the flap material (to heavy duty), the air gaps, and lastly the top rad hose and maybe bottom.
Im ordering more cfm flow fans, bought some thinner rubber and foam for sealing edges. Ordering new steel flex hoses. If that doesn't do it I'll light it on fire. Lol
Timing is 10 initial 32 total. Engine is a 383 stroker, aluminum heads, air gap intake, holley 750 DP, cam is a 272/272, 10-1 comp flat top forged pistons, 1 3/4 headers to 3" stainless exhaust. Makes 365 RWHP on a mustang dyno.
I never had a cooling problem till I went to electric fans. So shroud and not enough cfm I believe is the main problem.
I copied the C5 shroud but put cutouts for highway flow. I'm going to block them off for now. See how that works out.
the actual fans appear to be very low cfm also based on power requirements.
Let me clarify my statement. Cooling wise, reliability wise the stock setup can't be beat. A few years ago one of the car magazines did a test on different fans ranging from the stock setup to those flexi things and an electric setup. Yes the electric fan when it wasn't running there was no parasitic horsepower loss. The stock 7 blade clutch fan only lost a few horsepower. You have to ask yourself, is it really worth doing? Has anyone here run their car down the track and saw a difference in their time slip? For those who solve their cooling issues with electric fan setup, something must been seriously wrong with your clutch fan or something. The stock fan can suck a golf ball through a garden hose!
Let me clarify my statement. Cooling wise, reliability wise the stock setup can't be beat. A few years ago one of the car magazines did a test on different fans ranging from the stock setup to those flexi things and an electric setup. Yes the electric fan when it wasn't running there was no parasitic horsepower loss. The stock 7 blade clutch fan only lost a few horsepower. You have to ask yourself, is it really worth doing? Has anyone here run their car down the track and saw a difference in their time slip? For those who solve their cooling issues with electric fan setup, something must been seriously wrong with your clutch fan or something. The stock fan can suck a golf ball through a garden hose!
With a 6 blade fan (7 would be worse) and stock clutch these guys found a loss of 7lbs of torque and 14hp, more than "a few". Ive seen other videos that show as little as 7hp on a dyno with similar hardware. My argument is many here will spend hundreds on upgrades elewhere like an intake manifold to get say 7hp and no body shoots them down yet when this subject comes up its always downplayed.
Last edited by augiedoggy; Sep 4, 2024 at 01:51 PM.
You just solved your own problem : the electric fans/ shroud setup is inadequate. Go back to the clutch type fan and factory shroud, it can flow up to 3500 CFM when needed. And don't worry about the 5 Hp gain with electric fans, you can't use it anyway not with high engine coolant temps.
Thats the thing... the 7- 14hp you lose with a clutch fan is still like 5-7hp even if the engine is cold and not up to temp and the clutch isnt fully engaged.
We have folks here installing motorcycle batteries to shed a couple lbs or swapping in an edelbrock intake or oversized carb for 7-14hp Yet doing something much less radical such as going to a more efficient modern part time fan system seems to get far more flack even though its low hanging fruit.
So, let's say a clutch fan robs 5 - 10 horse from the gross HP.
So, what if we switch to electric to gain back the loss horses.
But wait !! Now the alternator has to work overtime to run the extra load of the fans. What If the alternator takes 4 - 8 additional horse to function now?
Kind of like those electric Water-Pumps, to save HP on a dragging mechanical impeller.
H-m-m-m-m-
Last edited by HeadsU.P.; Sep 4, 2024 at 04:47 PM.
