Radiator Fan CFM

rusty_408

rusty_408

Rusty
I Support the NLOC
I've searched and I'm sure it's beat to death, but i still cant find a clear answer... and am probably overthinking it.

Truck is still coming together, home stretch... Maxed out Novi 2k on a 408w. Maybe 650-750hp guess.

What is the guideline for CFM (or watt) rating on radiator fans? I have read that a motor like mine needs over 4000cfm of cooling to be reliable. I'm using the SVE 3 row radiator. Contour and Volt fans are like 3600cfm. Vintage Air and Camaro fans are rated up to like 5000cfm, but man, they can pull almost 60-70 amps if they need to go wide open.

Help me out please. I'm in analysis paralysis.
 
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I street drove something that made over 1300 to the tires on a stock radiator and clutch fan. There's way more air moving over the radiator when you're in motion than the fan provides. If you're not doing road race events, you won't ever have a problem.

My red truck, which is somewhere around 800 hp, I drove for years with a stock radiator and clutch fan. Now twin Spals that I run at 60%, and cycle based on temperature. I did replace the radiator recently with the SVE because the stocker started leaking.

Run it. If you have problems, upgrade it. Story of my truck's life.

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^^^What he said. People way overthink their fan needs. The only time you need the fan is when the engine is doing the least. The truck moving will likely be generating 4,000 cfm by 15-20 mph.
 
If you read up info on Delta Pag's fans they 100% recommend turning off the fans past a certain MPH (40 I think).
 
I got the flex a lite 298's on my truck and they do pretty good. Got built in soft start too which is nice. Says they pull 4600 CFM but who knows.

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I use the Flex A Lite 295's (same fans as 298's) with a VSC, which does a 'slow roll' start on the fans so it's easy on my stock alternator.

With these fans, you're looking at about a 28A draw on your electrical system, at a max of 4600cfm. It also has an input to control the fans when the A/C clutch is engaged.
 
I run the stock fan and radiator and it seems on a 95ºF day at idle it will creep to low 200s if I idle in traffic long enough but wont overheat, once going a steady 10mph+ it will creep back down and with any steady actual speed 40+no issue at all. And that's with a decent amount of hot turbo stuff under the hood and a fairly sized intercooler infront of the rad. So my theory there is any electric fan that will flow more than the stock fan does at a idle "should" be sufficient.

@FMOS Racing I believe I remember you posting something about shutting your electrics off at 50mph but it would creep? maybe I'm mistaking with someone else?
 
Thank you all!

JD has an early model GT500 fan on the truck. I Decided to overhaul the shroud and just use it as is for now. Used the straight 6 shroud and fitted it to the fan. I’ll run this for the time being and watch my temps.
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Like oilwell1415 said; the only time you will start seeing temps rise is when the vehicle is not moving. My old Brand "X" car with its sbc and a 5-blade Flex-a-lite fan was good up to an hour of barely moving traffic; then it would creep up. Highest temps I saw in that car was 210*F; but once I got moving, it would quickly drop-off to 185*F.

With that said, rusty_408: that's a nice fan setup you made :) I had to do something similar with my 351W powered Crown Vic. Used some scrap metal and hardware bought at the local Home Depot to make my twin Flex-a-Lite e-fans work with an aftermarket radiator. Probably overkill since that car won't be seeing much traffic LOL
 
Thank you. I’ll try it for now. I may upgrade to the later model gt500 fan which flows more or go brushless spals. If I do I’ll put this one in my yellow truck (stock engine).


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flex-a-lite 295 with variable speed controller. it pulls very little amps and my 130 amp alt has no problems with it. thIeir controller is nice and the setup can pull as much as 4600 cfm
 
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