Electric fans

[Sammy]

To start off I have always used a shroud for any V-8 application in the past. Now my question is this is it really necessary to install a shroud on an electric fan? Look at most every chevy pontiac V8, V6 even 4 bangers now days. They mount the electric fan against the radiator in a flimsy plastic thing not even close to a shroud. Even some aftermarket ones are held on with quick ties with nothing more than a rubber insulator for vibrations. Also I know a board member with a very high quality nice truck that had a shroud custom made that claimed he had to remove the shroud and put 3 or 4 large 3 in diameter holes to allow the air to freely pass thru because of overheating which resolved his dangerously high temps in mid summer. I may try it without the shroud to test this theroy. Appears to me that this shroud thing may be an overkill if your fan is sucking thru the rad at a efficient rate.

[GruntMoanCough]

IMO, a shroud is not neccessary if the fan is close to the radiator and it covers a good portion of the radiator as well.

[67chevy2wd]

a shroud is used with a belt driven fan so the fan has to pull air through the rad. If you use a belt driven fan without a shroud the air is not pulled through the rad very well. Electric fans are mounted right on the rad and don't need a shroud. That is my $.02

[GMCPaul]

A shroud is extremely important to use when using a electric or motor driven fan for cooling, the electric fan manufactures state that if you use a electric fan mounted to a radiator it should cover at minimum 70% of the fins, going by our radiators which off the top of my head are 19" X 26"= 494 sq inches
a 16" fan with a square framed body surrounding it covers 256 sq inches just slightly over 1/2 the radiator fins ( If it has a round housing surrounding your electric fan instead of a square body housing coverage of fan is even less ). If you use a shroud that covers all fins and mount the fan to it it then draws the air over all 494 sq inches instead of over only the area it covers. The electric fan manufacturers also say that they should be mounted rigidly to the radiator and that it is not recommended to attach them directly to the fins as it can lead to damage to the radiator fins over time caused by vibration.
quotes from Flex-A-lite web site
""Can the fan be mounted through the core, or will I need brackets? (Flex-a-lite recommends rigid bracket mounting for electric fans whenever possible to prevent damage to the radiator core.)""
""NOTE: Flex-a-lite does not recommend using an electric fan for the primary cooling source on 4-core radiators. Flex-a-lite recommends at least 60% of the finned core area be covered by an electric fan/shroud assembly for optimum cooling.""
""Generally speaking, it is best to maximize finned core area coverage and airflow capability when choosing an electric fan for your vehicle. For example, you may be able to fit 2 14” Trimline fans or one low-pro-file dual fan assembly on your radiator. The two separate fans have a bit better airflow potential, but the dual fan assembly would be a better choice because it covers a much larger area of the core.""
""When installing an electric fan how much of the radiator needs to be covered ?
We recommend 70% of the radiator core be covered.""
""How important is it to have a shroud around my fan ?
Very, one of the properties of air is that it likes to follow the path of least resistance. With a shroud you force the air to be drawn through the radiator instead of around it.""
""Which type of electric fan is better, a pusher or puller ?
For primary use a puller. For auxiliary use a pusher. ""
GMCPaul

[67chevemall]

Very nice. I went with a shroud. But had the same debate in my head.
More is always better

[big_al_71]

Flexalite dual fans and a four core aluminium griffin radiator have worked perfect for me. In this 93 degree hot humid miami weather with the a/c on in traffic with my fully built 406 the temperature in the truck does not go past 160 degrees. They do have a shorud not too big....see pict..It was a bit pricey to do this set up but it has worked like a champ.

[Sammy]

My engine is in the standard front location. Today I installed a serpentine system for the 5.7 L. I have both water pumps one designed for a clutch type fan, the other for an electric fan. I also have a 4 core rad. Distance between the rad and the closest pulley (the Waterpump) which is center is only 4 1/2 in. Every electric fan I can find is 4 1/2 in. So I installed an electric fan offset from center to miss the water pump. I do have room for a smaller one just to the left near the pwr steering pump. I will have to either get another smaller fan for that or find a puller fan to put in front as I do not have room for a shroud. I'll take pics tomorrow. Spent 2 days in the junkyard getting this far in 105 degrees baking sun. I can't return to the clutch fan for the serp system as The 4 core will not allow room for the blades.

[Sammy]

Anyone have a thinner fan than 4 1/2 inches. I need one at the most 4 1/4.?? Anyone make one?

[dieselarmy13]

I'm kinda in a hurry, so I didn't read all of the post's, but check this out--FAN

And yes, you do NEED a shroud.

[mrein3]

A couple of things.

First you need a shroud. Period. The fan shroud directs air across the whole radiator. If you ever get caught in stop and go traffic or let your truck idle, and you don't have a fan shroud, you're going to overheat.

Second. Electric fans are on all new cars now a days because they are WAY more efficient. On a belt driven fan the fan is always running. Even though the drag may be light it is still robbing power from your engine which decreases fuel mileage thus increasing fuel consumption. And if you believe this global warming crap it increases the man made destruction of the planet. An electric fan only comes on when needed and since it is running on electric power from the battery it is easier on gas. (It actually does take some fuel to turn it because fuel turns the alternator which supplies the battery).

Long story short, find a shroud that will work with your fan or get an electric fan and shroud assembly.

[Sammy]

Had a long talk with a custom rad shop today. He is custom building me a shroud with two 17 in fans. (setup will use approx 97% of the rad fins) Plus a probe in the drain cock for custom temp for the fans. I like that idea reading n controlin the fans from the rad. Pics tomorrow.

[67chevy2wd]

What kind of a shroud are you talking about when you say electric fans need one? You aren't talking about a shroud for a regular belt fan, your talking about the shrouds that are built/come with the electric fans right?

[dwcsr]

I came across the same issues with my 72. It heated up while towing. I was using a 16" 3000 cfm fan mounted in the original shroud. I ended up mounting an 18" Lincoln Mark VIII 2 speed fan and cleared up my over heating issues. The setup is here http://www.thehollisterroadcompany.com/MarkVIII.html its a real easy install.

[Boog]

That's some good info right there. I'm not too interested in dropping 4 or 5 large for a fan and shroud unit for my driver but this is more reasonable. I ran across a large fan/shroud last weekend in the salvage yard just laying in the bed still attached to a rad but I didn't grab it as it was an aftermarket unit of about 16" diameter and only covered just over 1/2 of the rad. Definately not a Taurus or Lincoln piece.
Like others I would like to mount a fan in the center but the depth of the fan is an issue unless you go with a thin fan assembly.
I have yet to see anyone use a dual fan assembly from later model chevy trucks on our 67-72s. Surely someone has tried it. I'm all for using chevy parts on chevy trucks if at all possible. Hey I'm just that way alright?

[dwcsr]

I did a lot of reading on the Mark VIII fan and some of the 300Z owners are dropping in LSx engines in those little cars. They found that by using a thinner 2 row radiator not a thicker 4 row and using a 18" Mark VIII fan it actually cooled better than a 4 row and 16". This kind of goes against the tradtional thinking of more cooling add more rows. I think the idea is that 2 rows and a lot more CFM does the better job.

One of the issues with after market fans under $300 is that they can't pull anywhere near the cfm that a belt driven fan with a fitted shroud pulls. The Mark VIII pulls between 3000 cfm on low and 4500 cfm on high thats fairly close to a belt driven fan so you can use thinner or stock radiators and get the same result as a high dollar aluminum with a dual fan setup.

One thing I did notice in my research was that the Zirgo I was using had a lot more support webbing for the fan motor than the Mark VIII and I can't help but think that it contributed to lower cfm of the Zirgo. My Zirgo was 2 inches smaller but it was faster RPM wise than the Mark VIII on high and while I would expect the Zirgo to be lower in CFM it should not have been that great a difference in CFM at a faster speed.

[Sammy]

As promised I have pics. Picked up my fans n rad today installed it. Having an issue with the serpinteen that I had powder coated. Thought it maybe a problem before I had it coated. This serp had a airpump in the lower passenger side of the bracket. Now having issue with the lwr rad hose fitting with out being kinked. May have to remove everything and cut the pump area down next to the block. This serp isn't cast it is steel so shouldn't be an huge issue. Just that I just got it on the engine. And you have to install the water pump after the serp as it isn't two piece like the cast ones are. Also found out that out FAQ on CS130 alt part nembers are no longer good. I searched several sights looking for the right pigtail with the resistor. Finally on Painless web site they show each of the three cs130 Alt types with a pic. And have a part number for the correct pigtail to fit yours. I went to NAPA, DELCO, AUTOZONE, PARTSAMERICA used to have them but they are bought out by O Rielly's and they are still searching for Vanna White to buy vowels so I didn't waste my time. I did find an Radio Shack that has 5 watt 100 ohm resistors which requires you will need a pin for the pigtail which I didn't have .. Ohh well ordered one thru Painless $!9 part # 3705 or 3706 or 3707 depending on which CS130 Serp Alt you have. And they have easy photos for your ID which one. So you will not need to spend half the eve looking all nite.
enjoy..

[Sammy]

3650 CFM virgo fans, 2 1/2 " depth 16 I think diameter, ADJ thermostat 160-200 degrees fits in the drain cock.