[FrankieT/A]

On another note, this fan (Flex-A-Lite #295) technically is a replacement fan for a Silverado. I have it in my T/A it seals to the core perfectly. There are no air leaks whatsoever. It's not going to a first gen F, but second gen F and I'm sure it would fit an A body. Besides fit the number one reason I picked this fan was it is the only aftermarket fan with a 4600CFM rating, nothing else comes close.

In my opinion there is no electric fan set up that will pull more air than a mechanical stock set up. BUT, all new cars performance or not have electric fans with no issues. You would be better off with a junkyard electric fan/shroud combo than just about any aftermarket setup. They are just better engineered. My son has an Xtreme blazer with 6.0L and A/C he is using a dual electric fan and shroud out of Dodge Intrepid and he has no cooling issues with or without A/C on.

[FrankieT/A]

Originally Posted by HWYSTR455

Yeah, it's like 4600cfm, will suck a beer out of your hand if you get too close when it comes on!

They draw 28a each, 56a total, which is a hard hit on the alt/electrical system. Need to run a controller with it.

I agree with both comments: when my fans kicks on if you standing near the grill it it pull your Tee shirt toward the grill.

When it kicks on it is a hard hit to the electrical system. I have separated the two fans by having Fan 1 kick on first then Fan 2 right after. But, when I turn on the A/C its a triple hit actually quadruple, both fans, compressor and blower. I'm working on that issue now.

[nUcLeArEnVoY]

Originally Posted by FrankieT/A

I agree with both comments: when my fans kicks on if you standing near the grill it it pull your Tee shirt toward the grill.

When it kicks on it is a hard hit to the electrical system. I have separated the two fans by having Fan 1 kick on first then Fan 2 right after. But, when I turn on the A/C its a triple hit actually quadruple, both fans, compressor and blower. I'm working on that issue now.

'78 T/A? Get one of those fancy serpentine belt systems that come with those powermaster 170 amp alternators. That's what I plan to do. 170 amps should be plenty for all that stuff, including EFI if you throw that into the fray, but an alternator with that output is going to need something more reliable to drive it than a V-Belt which is where the serpentine comes in. Oh, and some big chonkin' wiring. LOL

[FrankieT/A]

Originally Posted by nUcLeArEnVoY

'78 T/A? Get one of those fancy serpentine belt systems that come with those powermaster 170 amp alternators. That's what I plan to do. 170 amps should be plenty for all that stuff, including EFI if you throw that into the fray, but an alternator with that output is going to need something more reliable to drive it than a V-Belt which is where the serpentine comes in.

That's a $1500 dollar fix. You could just change the alternator...My alternator puts out 110 amps as it is. It handles the amp draw no problem. Its the initial shock.

[67Fbird]

https://www.youtube.com/shorts/7YvyMTSFpg4

enough to suck small children off of the sidewalk...

[62posbonny]

Thinking outside the box here, but what about using something like a .5 farad capacitor like one made for high power amplifiers? Run your fan relay power source off the capacitor and that would absorb the current shock.

[FrankieT/A]

Originally Posted by 67Fbird

https://www.youtube.com/shorts/7YvyMTSFpg4

enough to suck small children off of the sidewalk...

If you get too close you can lose ideas...

[67Fbird]

a simple fan controller will do you pretty good to help manage your turn on loads.

[noalibi]

Enjoyed the comedy in recent posts. Problem was def the fan/airflow. I removed 16" electric and mounted a 18" mechanical flex fan, still have the gutted t-stat. Waiting on Moroso full flow, but running (2500 rpm) 30 min at a time the gauge never rises off the needle-stop (100 degrees). After 30 minutes, shut down, gauge will rise to 175-180. Gonna drop in a 160 t-stat and let the fun begin. Gotta get better e-fans for my test stand though (thinking "black-hole" sucking specs ). Thanks for all of your input, all was thought provoking and useful.

[tom s]

Temp always goes up after engine is turned off!Tom

[punkin]

Originally Posted by nUcLeArEnVoY

'78 T/A? Get one of those fancy serpentine belt systems that come with those powermaster 170 amp alternators. That's what I plan to do. 170 amps should be plenty for all that stuff, including EFI if you throw that into the fray, but an alternator with that output is going to need something more reliable to drive it than a V-Belt which is where the serpentine comes in. Oh, and some big chonkin' wiring. LOL

I went with a Mechman 280 amp (if I recall correctly). They recommended a garden hose sized cable. This has turned into a "while I'm at it", rewiring the car. LOL.

[HWYSTR455]

Originally Posted by 62posbonny

Thinking outside the box here, but what about using something like a .5 farad capacitor like one made for high power amplifiers? Run your fan relay power source off the capacitor and that would absorb the current shock.

That's what I do, I run dual 1 farad caps, and it does help save the regulators in ALTs. Go back 15 years and look at my posts about eating ALTs. The fans kicking on/off/on/off in traffic would destroy ALTs in short order.

Like previously mentioned, the max amp ALTs that I've found which can handle a V-belt is right about 140-150a. Over that, and the belt will slip. Even with a fresh belt, and properly tensioned, 150a is borderline.

I say use a large cap and a PMW controller with gradual ramp-up. That does it.

If you wanted to, you could run an electric water pump, which drag racers do, and run the fans & the pump with the engine off between rounds to cool it.


.

[Formulabruce]

NO new cars have FLAT , sealed fan shrouds with electric fans. Also new engines have EVEN heat throughout for a more perfect efficient burn and emissions.
The ONLY set up that works best is a factory Clutch fan and shroud. This uses the LEAST HP, and cools the best. ( this has been proven on Hot Rod TV ( the pay side now).
That said, sealing the radiator to the core support and around it is huge too.
Obviously the 421 Mod is the cheapest way to go, but who wants to do that with a summit catalog at hand?? Fight, Fight, Fight!!

[TRADERMIKE 2012]

Originally Posted by tom s

use a lazer thermometer and check the temp going out of the radiator and also going into the radiator.Should be a 30 degree drop.Tom

Mikes Reply:

2x, I get 30-degree difference too using the inferred from Harbor Freight.

[HWYSTR455]

I'm curious, I don't recall what the '421 mod' is?

.

[TRADERMIKE 2012]

Originally Posted by Sirrotica

Look at race cars that run on a closed course for more than 13 seconds, you won't see any electric fans on them. I have no idea of why people think electric fans are superior to an engine driven one. They will not ever move the amount of air that an engine driven one will, and the aren't linear with heat production generated by RPM change.

Running a Pontiac on a dirt track will challenge anything you think you know about keeping one cool. I had to do some unorthodox things to keep mine cool, but when I got the system optimized, you would never see 180, no matter how hot, and humid the ambient air was.

Engine driven fan, with a RV style composite fan blades, 2, 3 core radiators back to back. A/C pulleys. As much radiator area as possible, and a fan that will pull as much air as possible through the radiator and shroud system. The composite fan is very light (11 ounces) has a near 90 degree pitch on the blades, so you run direct drive, no clutch. Even at idle it pulls a huge amount of air.

Not having a cooling system that could remove heat as fast as it was generated, cost me a brand new fresh engine. Having to completely rebuild a new engine that ran only 1 race, is a hard way to learn to have a cooling system up to the job. Expensive lessons are the hardest to swallow, but you won't forget it.

Mikes Reply:

My Brother-in-law raced @ Hiali in South Florida, short Track and they used to seal the sh*% out of the Shroud to keep under Hood Temps. out, plus they directed the air to the Radiator anyway they could with sheet Metal.

[TRADERMIKE 2012]

Originally Posted by RocktimusPryme

Its not that electric fans move more air than big engine driven fans. Typically they dont. However, most people whose classic cars are set up even close to correct only have a problem at idle or stop and go traffic.

At these low RPMs, a good electric fan will still be giving its max air flow where the engine driven fan is limited by the low RPM of the engine. So if someone can get more air flow at the area where their vehicle actually needs it, AND save 10-12 HP by switching to electric. Its an easy choice.

I say this as someone with a clutch fan setup running cool. The pitfalls of the electric fan is that people cheap out on them and get units that arent sufficient at any RPM.

Mikes Reply:

I run both and a side kick. The pusher takes up only half the Radiator space and is switched manually. The side kick is to counter the 30 degrees increase from the AC, when it's turned on manually too! The Factory 19" Fan and Shroud, plus A HD Temp. actuated Clutch is key. I also invested in the 3-hole bypass 180-degree Thermostat, the 160 works but I prefer the 180 because I have the crossovers blocked for hot South Florida days. I also made a tight tolerance at the water pump plate, so the water jumps over the top of my Radiator viewed with the cap off. As stated earlier there is a 30-degree difference between the upper and lower hoses and the lower hose has the spring, so it won't collapse under any circumstance.

[TRADERMIKE 2012]

Originally Posted by RocktimusPryme

Its not that electric fans move more air than big engine driven fans. Typically they dont. However, most people whose classic cars are set up even close to correct only have a problem at idle or stop and go traffic.

At these low RPMs, a good electric fan will still be giving its max air flow where the engine driven fan is limited by the low RPM of the engine. So if someone can get more air flow at the area where their vehicle actually needs it, AND save 10-12 HP by switching to electric. Its an easy choice.

I say this as someone with a clutch fan setup running cool. The pitfalls of the electric fan is that people cheap out on them and get units that arent sufficient at any RPM.

"However, most people whose classic cars are set up even close to correct only have a problem at idle or stop and go traffic."

Mikes Reply:

I find that it is changing to the Heavy-Duty temp. actuated Clutch Fan that made a very big difference for me, the normal one the 428 ci HO called for was inadequate at best. The Clutch will speed up the Fan when you are @ idle, so you don't have a hot issue even at a stop light, if you use the HD Clutch. I could literally see my Rally gauge Temp. go from 225 degrees to 180 degrees and maintain that temp. at all times, by installing the HD Temp. actuated Clutch Fan, 180 degree 3-hole Thermostat and the water pump Modification done simultaneously!

[TRADERMIKE 2012]

Originally Posted by HWYSTR455

Yeah, it's like 4600cfm, will suck a beer out of your hand if you get too close when it comes on!

They draw 28a each, 56a total, which is a hard hit on the alt/electrical system. Need to run a controller with it.


.

Mike Reply:

I have all the Extra options on my car and then some I created. The only one left for me is the Cruise Control. I went to a HD Alt. also, over 100 amps.

When I stand outside near the Hood scoop, I can hear the air being sucked into it. Put a piece of paper over the hole and it will stay stuck to the Scoop. I am running Tri-power Rochester Carbs.

Back to that Beer scenario, I could suck that Beer with a straw through the cardboard cover over the Scoop in seconds? I believe the Tri-power's CFM is about 800 or so, I have read.

[Sirrotica]

The 421 mod is drilling a steam hole in the deck surface that the head gasket has a provision hole for, but Pontiac never drilled the hole, except for a few select engines. The 421s were in that group, hence the reference to a 421 modification.

By drilling that hole it is said that it will improve the cooling by eliminating a steam pocket area by venting it to the cylinder heads.

I've never done it either, but probably would, if I were to build a fresh engine from this point forward. It wouldn't cost anything to try it, and eliminating a steam pocket can't hurt anything.