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post #46 of 59 (permalink) Old Aug 14th, 19, 11:15 AM
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Don
 
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Re: dual fans

50% might be a tad pessimistic but 80% seems a tad optimistic.

I would expect that you would have air recirculating back through the open sections of the core and will be interested to see how this works in practice. Maybe the fans are moving so much air that it wonít matter. You are definitely a disruptor with that design.

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post #47 of 59 (permalink) Old Aug 14th, 19, 12:25 PM
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Re: dual fans

OK 79%.

Of course I am the disruptor, I am the Firebird guy on the Camaro website.
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post #48 of 59 (permalink) Old Aug 14th, 19, 01:50 PM
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Re: dual fans

Just some more to look at.

If you go to the accessory drop down menu, they have a bunch of different SPAL fans with dimensions, some a real low profile,but they flow less also. They also list just shrouds in that same menu.


Griffin Performance Aluminum Radiators








I have a dual fan setup from Griffin, no issues at all in the Ca. central valley heat. But I currently have it wired to #1 fan on at lower temp, then fan #2 comes on at higher temp,Holley HP ECU controlled.
re-wiring them to both come on at low speed, then high speed for higher temp has been on my to do list for awhile now,
No doubt that is a better way to do it.




Just need to add on more relay to my setup.
Something like this.
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post #49 of 59 (permalink) Old Aug 14th, 19, 06:44 PM Thread Starter
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Re: dual fans

Well after much research and reading posts, I've decided to order the Flex A Lite 238. Last shot before I try my final try. I guess I don't trust the stated cfm's on my current fan. The 238 is supposed to be 3000 cfm, we'll see if it comes close and works for me.
My other alternative is to switch to a short water pump to gain about a 1 1/2", could be costly, but I think that should work.


Thanks for all the suggestions.

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post #50 of 59 (permalink) Old Aug 15th, 19, 07:54 AM
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Re: dual fans

Quote:
Originally Posted by pittpens24 View Post
Here is a pic of what I am running currentlyAttachment 228609

Sent from my SM-G973U1 using Tapatalk
GREG... Curious, it looks like you're running a serpentine setup, but I'm just guessing. Hard to tell at that angle LOL. How thick is that setup and are you running a short water pump or an electric one? Would love to see more pix.

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post #51 of 59 (permalink) Old Aug 16th, 19, 01:53 PM Thread Starter
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Re: dual fans

Well, recieved fan today, and it doesn't come with mounting feet. They included 2 sets of mounts that zip tie thru the radiator. But I have a aluminum radiator, not sure if I want to do that. So, if anybody orders Flex A Lite fans you have to order mounting feet separate.

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post #52 of 59 (permalink) Old Aug 22nd, 19, 01:36 PM
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Re: dual fans

Quote:
Originally Posted by LeeC View Post
Well, recieved fan today, and it doesn't come with mounting feet. They included 2 sets of mounts that zip tie thru the radiator. But I have a aluminum radiator, not sure if I want to do that. So, if anybody orders Flex A Lite fans you have to order mounting feet separate.
Lee... I think the long water pump is the main obstacle to using a decent fan/shroud with either a stock or aftermarket radiator. I was at the crossroads, about to install my Vintage Air and I opted to order a short water pump serpentine setup. Once I get switched over, then I'll see how much space there is for a fan/shroud and also decide whether to get an aluminum radiator or not. Pix are not my setup but a couple of FB guys who have BBC's and Champion 4 core radiators. I believe the model is MC370. They are very happy with their setups.
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post #53 of 59 (permalink) Old Aug 27th, 19, 07:25 PM
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Re: dual fans

Not sure why your engine is so close to your radiator. Even with LWP I have tons of room with a SB.


Steve
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post #54 of 59 (permalink) Old Aug 27th, 19, 08:31 PM
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Re: dual fans

Quote:
Well, recieved fan today, and it doesn't come with mounting feet. They included 2 sets of mounts that zip tie thru the radiator. But I have a aluminum radiator, not sure if I want to do that. So, if anybody orders Flex A Lite fans you have to order mounting feet separate.
Mine is mounted with the zip ties and never had a problem even with my previous Haydn fans. Pep Boys always had the replacement zip ties if you had to remove.

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post #55 of 59 (permalink) Old Sep 2nd, 19, 06:06 AM
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Re: dual fans

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Originally Posted by scblucam View Post
Mine is mounted with the zip ties and never had a problem even with my previous Haydn fans. Pep Boys always had the replacement zip ties if you had to remove.
This is a great thread. I've heard all sorts of opinions about shrouded fans versus un-shrouded, dual versus single, it seems like different solutions work for different motor, power, and fan combos. Personally, I kinda feel that even a 3/4" shroud will help direct air to the fan and pull more Air past the coils.

My last ride was a supercharged SVT Lightning and I had a big single Lincoln-based eFan that was sold as a kit by JDM (Ford tuning shop in NJ). It worked flawlessly, even had a manual override switch on the firewall to run the fan between passes at the track.

I'm trying to figure out what'll work best in my car, currently has a mild 461 BBC, 4-core curved neck copper/brass radiator, and since I'm going serpentine, some sort of eFan is in my future. Questions I have:

1. Would a single big fan with a shroud do the trick, or would I be better off with dual fans?
2. Would I gain anything other than a weight savings with an aluminum radiator?
3. Is anyone running an eFan setup with a factory BBC and if so, single or dual?

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post #56 of 59 (permalink) Old Nov 5th, 19, 07:47 PM
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Re: dual fans

Quote:
Originally Posted by tp_smith View Post
I have two fans bolted to the radiator core. They do not have a shroud. Between the radiator fins and the fan frame is some foam type material. The foam keeps the fan from drawing air between the gap. The foam forces the fan to pull air through the radiator fins. This is an easy fix for your fan(s) that will help with your problem.



I agree you should never run only one fan in a two fan setup. If you do, the fan that has no power will turn the opposite direction. The non-powered fan is "wind-milling". Hot air that was drawn through the radiator by the fan that is powered is looped back to the front of the radiator by the fan with no power.

Two fans that are wired in series will turn at half their base speed. Air flow is not linear relationship. An axial fan turning half speed will have somewhere around 25% air flow. It is better to have 25% air flow rather than having a fan windmill and circulate hot air.

Fan manufacturers that give you an airflow without providing the static pressure is very misleading. In my opinion, an airflow number like 2500 cfm alone is a meaningless number.

My two fans are made by SPAL. They are model VA03-AP70/LL-68A.
Here is a real spec for my 11 inch axial fans running at 13 volts DC:

Static pressure in inch H20***Airflow CFM**Current
0***********************1298********12.3 amps
0.8**********************614********14.4 amps
1.6**********************0**********19.6 amps
The stars are to keep the columns in alignment.

Notice the higher the restriction of airflow (high static pressure), air flow drops and the amps drawn by the motor goes up. The first row is when the fan is running with absolutely no restriction. It is running in free air. The last row is when the fan's air flow is completely blocked off.

Manufacturers that give a CFM number without the static pressure is probably the most optimistic number. It is the first row with the fan running in free air and drawing the least amount of amps. You stick a radiator in front of this fan, airflow goes down and amps go up.
Pat... Did you fab the "brackets" you're using to hold the fans up against the core? Or were they part of your radiator/fan kit? My Cold Case radiator arrived a couple hours ago, I'll probably wait till Thursday to bolt it in place and then see how much room I have for fans. My issue is a BBC and serpentine belts. If I have to, I can probably fab a somewhat similar bracket on my buddy's CNC plasma cutting table. Could even fab a shallow shroud if I wanted to and could fit it. What thickness are those brackets? Let us know how it works out with regard to cooling.

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post #57 of 59 (permalink) Old Nov 6th, 19, 06:42 AM
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Re: dual fans

Quote:
Originally Posted by 57vette View Post
Pat... Did you fab the "brackets" you're using to hold the fans up against the core? Or were they part of your radiator/fan kit? My Cold Case radiator arrived a couple hours ago, I'll probably wait till Thursday to bolt it in place and then see how much room I have for fans. My issue is a BBC and serpentine belts. If I have to, I can probably fab a somewhat similar bracket on my buddy's CNC plasma cutting table. Could even fab a shallow shroud if I wanted to and could fit it. What thickness are those brackets? Let us know how it works out with regard to cooling.
The bracket and the fans came with the radiator as one assembly. The bracket is made of aluminum that is about 1/8" thick. The bracket is surprisingly rigid considering how little the amount of metal is used to support the fans. The bracket is one piece. It was probably made with a CNC machine from a plate of aluminum.

Here is a link to a Jegs that have some more photos of the brackets to give you different views:

https://www.jegs.com/i/C-R-Racing/058/15-11010/10002/-1

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post #58 of 59 (permalink) Old Nov 6th, 19, 03:00 PM
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Re: dual fans

Quote:
Originally Posted by tp_smith View Post
The bracket and the fans came with the radiator as one assembly. The bracket is made of aluminum that is about 1/8" thick. The bracket is surprisingly rigid considering how little the amount of metal is used to support the fans. The bracket is one piece. It was probably made with a CNC machine from a plate of aluminum.

Here is a link to a Jegs that have some more photos of the brackets to give you different views:

https://www.jegs.com/i/C-R-Racing/058/15-11010/10002/-1
Thanks for the link. Poked around looking for specs of those fans. Apparently they pull 1298 CFM max and all the technical stuff suggests the CFM goes down as the static pressure goes up? I'm curious about how its working for you, as I'm a novice when it comes to calculating all this CFM stuff LOL. I guess the bottom line for me (and others) is what kind of CFM is needed to cool a mild BBC? I had thought you'd need a minimum of 3000 CFM, maybe even 3500 CFM.

BeCool has a complete shroud/dual 11" fan system Model 75007 that fits the Camaro 23" X 17" core, its supposedly rated at 2750 CFM the deepest part (Motor cover) is 4.25" from the front of the shroud.



I may have to fab a shroud or perhaps a bracket similar to yours because of space... but I'm really curious about what's the minimum amount of CFM that'll work in a dual or single fan setup. One of the guys here (GordR) adapted a Ford Contour dual fan setup, they supposedly put out around 3800 CFM, but I have no clue about dimensions of the Ford shroud as adapted. He sold the Camaro a couple years ago but said it did a great job. Might look into that further, but if a decent pair of 1300 CFM fans would do the trick, it opens a lot of options including Mishimoto fans.

One thing Iíd like to see is some CFM specs on a stock fan at idle, and maybe 1500 rpm. Itís a given that once you surpass 30 mph, the air being pushed thru the grille/radiator starts to surpass what the 7-blade mechanical fan can pull, thatís why clutch fans disengage when enough cool air flows over the fans coil. Likewise, most eFans are wired so they only come on when coolant temperatures surpass say... 195 degrees, then shut down at 180. So in a nutshell, your eFan setup not only saves horsepower, it does a better job at idle in traffic and low rpms than a mechanical fan because it can run at full speed or perhaps half speed if itís a two-speed setup.

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Last edited by 57vette; Nov 6th, 19 at 06:22 PM.
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post #59 of 59 (permalink) Old Nov 7th, 19, 11:00 AM
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Re: dual fans

Mr. Mike, I donít think I ever wrote to you before. I tend to write novels if I get the slightest bit of encouragement. You are pushing that button. I will try to keep out of the weeds on this thread.

To select a fan, you need to know four things.
1. The desired flow rate measured in CFM.
2. The static pressure of the system measured in inches of water (SP).
3. The air density.
4. The type of fan.

1. You mentioned the desired flow rate for a big block Chevy is 3000-3500 cubic feet per minute.
2. What is the static pressure of your radiator? Nobody knows. This is why you are concerned if you are making the correct purchase. The manufacturer does not publish the numbers. So, you try to make an estimated judgement. Compare the little holes the air flows through with your stock radiator. Are they about the same size? If they are bigger then the static pressure will be less. Do you have a larger radiator is terms of height and width? If it is larger radiator then the static pressure will be less because it has got more little holes. How deep is the radiator? If it is thicker, then, the static pressure will be more. How much more? Who knows? So we go around in circles and never come to a conclusion.
3. I live about 20 miles outside of Houston, Texas. The altitude is 112 feet above sea level. The air is dense here. A person living in Pittsfield, Massachusetts (1000 feet above sea level) will have a radiator that will run hotter than mine.
4. An axial fan is the only type that will fit.

So how does someone pick a fan? It is almost impossible to pick too large of a fan. If you managed to pick one too big, the thermostat will regulate the temperature and not let the motor run too cold.

In the past, I use to do work cooling semiconductors on heat sinks. Blowing air across the heat sink fins makes a dramatic improvement in the transfer of heat. A gentle breeze would bring the temperature down drastically. When I blow more air, there is a point where a lot of air does not lower the temperature. The heatsink temperature hits a plateau and just stays about the same temp even though more air is blown across it. If your car is running hot, sometimes more air is not the solution. You need a bigger radiator.

The biggest factor to get the most cooling is to pick the largest fan that will fit. You picked two 11Ē fans. I donít think two, 12 inch, fans would fit on your radiator. So, the size of the fans you picked is the best option for your radiator.

The number of fan blades will affect the flow rate. More blades mean more CFM. The pitch of the fan blades matter. There is a sweet spot on fan blade pitch. The sweet spot is where the fan moves the most air with the least amount of current.

The blades can be straight or shaped like the letter S. The ďSĒ shape blade will be less noisy but not as efficient.

You picked a Be Cool fan assembly model 75007. It comes with Spal fans. This assembly looks very much like the Spal 2VA06-AP6-37A fan and shroud assembly. Here is a link to the Spal assembly.


https://www.a1electric.com/spal/specs/30102052.pdf

I compared my fans to your fans. Our fans are both 11 inches in diameter. My fan has seven, S shaped, blades. Yours have five, straight blades. I think the blade pitch is greater on my fans, but I cannot be sure.

At 0 inches of water, (fan is running in free air), your fans will outperform mine. Yours will flow more air. Your fan will continue to be better up to 0.4 inches of water. The range between 0.5 to 0.9 inches of water, my fans will flow more air than yours. At one inch of water your fan is the better one.

This tells me your Be Cool radiator fans will cool better than mine as long as there is little restriction. I am stacking an AC condenser and an air to water heat exchanger in front of the radiator. I have a lot of restriction, so it is more important to me the range of 0.5 to 0.9 inches of water flows a lot of air. This is the area of the fan curve I am going to be operating.

You picked about the best fan assembly for your car. The only way you are going to get more airflow is to buy a fan with more blades. You donít have an intercooler. I am not sure you have a condenser. I really think your mild big block will stay cool and happy.
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