...and I got relays on my mind, yes I got relays on my mind

[Turbogus]

Yeah, I can dig that, IO

 

[Niedhogg]

Just for the record, I am almost always here but the expertise level of this forum is so much higher than it once was, about the time I get ready to post something some one else has done a good job of covering it and took the words right out of my mouth.

It's been my experience, that this younger crowd can type a few hundred words a minute, and that doesn't give us "experienced" guys much of a chance to reply...

 

[thiswontbetooexpensive]

It's been my experience, that this younger crowd can type a few hundred words a minute, and that doesn't give us "experienced" guys much of a chance to reply...

I used the word "seasoned" to describe some of my co-workers with over 30 years of experience each in a meeting. (One of them took offense, but I excused it for his being from West Texas; the wind and sand out there has a way of changing folks...)

I can type pretty fast, but that doesn't mean I know the subject any better! Please dont let typing speed or response time dictate whether or not the question warrants a response.

Experience trumps enthusiam every day in my mind!!!!!!!

 

[mtnwhlr]

We have gotten alot of new guys here that really know there stuff I think it just makes this site that much better.

 

[IOPort51]

Now , changing the subject back to relays and fans.

Here is the mount and the twin 10" fan setup I have built for the CJ5 . I am thinking of running them on 25 amp fuses with a 40 amp relay for each. I may or may not put a kill switch on them.

 

[thiswontbetooexpensive]

IO, will those run independently or together? Also, do they come on with the engine on or just on a switch? I have been kicking around electric fans but I am concerned about the noise they make bothering me. I like quiet.

(Nice work on the bracket BTW!)


This won't be too expensive Dear! That's what I keep saying. Over and over again.

 

[007]

Not trying to be a pain, but I'm curious as to how two small fans is better than one? In most cases, the area of one fan is much larger than the area of 2, BUT that's area only - not CFM.

Do electric fans flat out pull more air through the smaller area than one original standard fan does through a larger area?

 

[CJ]

Not trying to be a pain, but I'm curious as to how two small fans is better than one? In most cases, the area of one fan is much larger than the area of 2, BUT that's area only - not CFM.

Do electric fans flat out pull more air through the smaller area than one original standard fan does through a larger area?

Actually two smaller fans usualy have more surface are than one large one.

It works this way, one 12" fan = (12 x 12) = 144
Two 10" fans = ((10 x 10) = 100 + (10 x 10)) = 100 for a total of 200

As you can see by reducing the fan size just 2" but doubling up on them you have increased the surface area by 28%.

 

[thiswontbetooexpensive]

12" fan =113.076square inches of surface area

Two 10" fans=157.05square inches of surface area.

The real difference I can see is how much air it will move in CFM's across the radiator and is thusly explained:
12"fan moves about 150cfm. 10"fan moves about 110cfm but this gets doubled because you have two totaling 220cfm. I have never had a problem with a stock engine fan, but I haven't done any rock crawling or anything of the sort.

I like creeping around at idle speed all sneaky-like and quiet. I need to be able to hear nature in my outside endeavors. What is the noise output of a double electric fan? Is the cooling output worth all the racket?


This won't be too expensive Dear! That's what I keep saying. Over and over again.

 

[CJ]

Sure, use real math... (I simplied for our purposes)...

As for noise, just use variable speed fans - negligible sound @ the cfm you need...

 

[007]

So a stock fan is around 18" right? So pie x radius squared gives you 254.34 square inches. Two 10" fans would be 157 square inches. That's a 38% reduction in area.

The only cooling advantage that could be gained is through CFM...

Where am I missing something?

 

[CJ]

I never used an 18 calc, just compared a 12" fan to a dual 10"

12 dia = 37.7 circ = 113.1 area
10 dia = 31.42 circ = 78.54 area X 2 157.1 area

If you have an 18" fan with a great shroud and very good flow - that works great.

 

[CJ]

Lets get back on topic - Please start a new thread to discuss this further,

thanks,

 

[007]

Not sure where you are getting your calcs from but.

12 dia = 37.7 circ = 113.1 area
10 dia = 31.42 circ = 78.54 area X 2 157.1 area

My calcs are right. I've not measured mine but every replacement fan I find is over 18". I'm trying to compare stock vs. this Contour setup. So that's 18" vs. 10"x2 isn't it?

 

[CJ]

My calcs are right. I've not measured mine but every replacement fan I find is over 18". I'm trying to compare stock vs. this Contour setup. So that's 18" vs. 10"x2 isn't it?

Caught my post before my edit - lets take this to another thread and stop the hitchhike...

 

[IOPort51]

I think this is on topic.

Both fans will be controlled by a single temperature switch that makes at makes at about 180 degrees, this will be fused to control two relays which intern control one fan each. this does not give independent control but it does give redundant control. If the fuse , relay or fan fails there will be one circuit still working. One fan may not be as good as two but it is always better than none.

If I may address noise, I think the electric fan is much quieter than the original. the little 4 blade prop that was on it originally was about the noisiest fan I can remember hearing but you couldn't appreciate it until you removed it. The electric only runs when you need it, which is, surprisingly, not as much as you may think.

The big point here is that I can reduce the amperage on the single fan circuits which takes a lot of heat away from the relay and the wire feeding the relay/fan.

Waterproof 5 Pin 30-40 Amp Relay With Connector - The Repair Connector Store

these are my current favorite relays, by the way.

always remember: when it says "water proof" read "water resistant".

IO, will those run independently or together? Also, do they come on with the engine on or just on a switch? I have been kicking around electric fans but I am concerned about the noise they make bothering me. I like quiet.

(Nice work on the bracket BTW!)


This won't be too expensive Dear! That's what I keep saying. Over and over again.

 

[mtnwhlr]

Are you going to put in a cut off switch so you can turn them off when doing a water crossing? I would recommend it.

 

[IOPort51]

I am not sure but I think that if I were to drive through water deep enough to hit these fans it will not be a spontaneous thing and it may be just as easy to pull the fuse on the two circuits. This is not near as hard as it may first sound as the fuses for the fans ore under the hood on the drivers side fender. Another thing is that to reach these fans it is possible the distributor will go under first, I should measure that one of these days. The switch is not a bad idea just not, in my case, a very high priority one.

Are you going to put in a cut off switch so you can turn them off when doing a water crossing? I would recommend it.

 

[thiswontbetooexpensive]

Thank you for the explanation. Have a pleasant day!


This won't be too expensive Dear! That's what I keep saying. Over and over again.

 

[Turbogus]

So I'm nearing completion of my Contour/Mystique fan setup (long time comin' but I work 7 days a week) I hope that I installed the diode the right way;