400 sbc and electric fan help needed

[sev85]

guys i need help i have a 1982 gmc high sierra 4x4 i droped a stock 400 small block minus a very mild cam headman headers i believe 1 5/8 to 3 inch collector edelbrock rpm air gap intake edelbrock 1406 600cfm electric choke carb with a 1 inch spacer stock belt driven water pump and i didnt have a fan shroud and it had too small of a fan so it was boiling over crawling around on trails and in the mud but would stay cool cruising down the road over 30 mph

i have installed a dual electric fan setup which covers about 90% of the radiator with shroud and switched thermostats from a 200 to a 180 high flow t-stat

today was 60 degrees and with one electric fan running all the time it maintained about 190-200 degrees if i clicked the second electric fan on it cooled it down to about 140-160 range (guessing on temps because the gauge has lines not actual numbers in between the lowest which is 100 and the highest that is 240)

the temp sensor is a electric sensor in the side of the head to a stock gauge with a aluminum radiator was told it was a 4 core but im thinking it is a 2 core

heres my question should i set one electric fan to run all the time and than put the fan controller on the second fan to kick on only when it is going to overheat or setup both fans on controllers one at operating temperature and the second only when over heating? also what is a good operating temperature for the 400?

because i have seen setups where if both fans run constantly they run the battery dead because the alternator cant keep up with the electrical usage it is a stock alternator off a 350 which i believe to be 80 or 90 amps i will upgrade later on when i have more money to a much larger 140 amp or bigger alternator because im planning on adding more electrical addons ( ie off road lights upgraded head lights a winch a sub and a amp and a upgrades to the stereo system

[68post]

Both fans on @ 200 and off at 180ish (wintertime),or alittle lower in summer. 180 is a great warm weather temp and 195 is a great winter temp - as far as thermostats go.

180 is a power temp , and 195 is great for engine longevity/emissions/mileage.

How do you like your 400 ??

[sev85]

i love my 400 minus the fact it keeps boiling over if im crawling or putting around under 25 mph the power is great and so is the low end torque i dont need it to wrap high the power is there off idle which is what i wanted if i can just get it to stay cool

so your saying to put both fans on at 200 and off at 180 with the fan controller right? because it will maintain a set temperature with one on all the time but i just dont wanna kill my battery when im out driving around turn the truck off and it not start lol

also give me a couple seconds here i will post pics of my build

[sev85]

this last picture is the junction blocks out of a 90s model chevy truck i am installing so i have a power source and ground source i can tap into as freely as i want for my relay box im installing for all the addons im doing like amp for my new stereo upgraded headlights and off road lights electric fuel and electric fans

[piecesparts]

With a two fan setup, the issue of starting amps and running drag on your electrical capacity is important. I have an 84 GMC with a 383 stroker engine, a Be Cool aluminum radiator, dual 11" Spal fans and a progressive electronic fan controller. My system is wired to turn the first fan on at a set temperature, which I picked to be around 170 degrees. The second fan comes on around 210 degrees, to back up the first one if the temps get too high. I run a 180 degree superT/stat, so the engine stays around that 180 without much issue. Believe me, the brag about a Be Cool radiator are true. Those things can carry a system without fans and not overheat. I have never had the second fan come on with my setup, unless I trigger it myself.

If you run both fans on at the same time, the voltage drop when they start can make your alternator overwork itself. That is why mine is setup to start in a series pattern. I did upgrade my alternaotr to one that carries 80 amps with the engine at idle RPMs. Many alternators only carry 35 amps at idle. That way my lights don't go dim at a stop light with the truck in drive and the fans running and myu stereo playing.

The first thing I notice with many people, that do electric fans, is that they put a lot of cash in the drive train and when it comes to the cooling part, they tend to try to save a buck. That is the one thing that protects your initial investment and you should be ready to spend wha tit takes to do it right. I have seen some "HIGH" dollar custom cars along side of a road with th eradiator boiling, since they did just that.

I also set up my 91 Silverado with the same fans and drove that truck for several years with no issues in overheating. I believe that the whole trick centers on getting the setup that moves enough air across the radiator to allow for cooling.

[sev85]

the alternator is supposed to be a 80 or 90 amp i will double check it when the sun comes up but im wiring the fans to pull power from a relay not from the controller which im still waiting for to come in the mail because none of my local parts stores carried one anyone suggested using so i had to order from online

i lucked into the aluminum radiator which used to cool my 355 nicely but since upgrading to the 400 the stock fan it came with was destroyed so i tried a slightly smaller one which was a big mistake which is why im now doing the electric fans and controller sadly being married with a 2 almost 3 year old and a 10 month old has me on a strict budget

but i was thinking about running the fans in series myself because of the massive draw they have and do you run a single controller or 2 individual controllers?

[homemade87]

I see you have a dual fan . The best thing is to have both fans run at half speed at the same time( you can do this by running the fans in series to each other) . When extra cooling is needed you need to kick both fans on high . You will have to do this with a 3 relay set up . This is how GM does it in newer vehicles . There is a harness you can get to do this or build your own (I got one off ebay ) . I did this in my 82 but it is controlled by a pcm for my ls swap . You will have to get two sending units or just one that will control the low and high speed separately along with the harness . Let the sending units control the on and off .

Also I see you have one off the plastic ended radiators . Those are usually pretty small cores . I would suggest getting a 1" 2-row alum radiator . This would be much better for your slow speed mudding under power pulls . Cruising on the road with the plastic one would be fine but that's not what you are doing.

I thing if you did these upgrades you would see a big difference .

[sev85]

ok appreciate it i will build the harness if necesary i have bad luck with bought harneses the radiator i will upgrade to a 4 core dual if not triple pass first chance i get the truck sees off road and on road use kind of a even mix of both but my isuues mainly come in off road use

[homemade87]

I found the harness I am using . I have had good luck with this one . The price point is also reasonable . I felt by the time I bought everything I would be more than half the cost . Also includes the fuses . Has cover also .

http://www.ebay.com/itm/Electric-Coo...21553362973?pt

[sev85]

yeah but heres the problem i run a carbed 6.6L 400 sbc not an ls so im gonna have to have something to control the fans modes and on and off

[homemade87]

[QUOTE=sev85;7043550]yeah but heres the problem i run a carbed 6.6L 400 sbc not an ls so im gonna have to have something to control the fans modes and on and off[/QUOTE

Forget about the ls . Does not matter . You will control with sending units in the engine .The senders will control the relays .Just get what temperatures you want the fans to come on. It will do the same thing . Install sender in the drivers side head for low speed and the other one for high speed in the other head or intake . Maybe 180* for low speed and 195* for hight speed. So if it does get a little warm the high speed will come on and cool things down . when it does it will go back to low speed fans .

[sev85]

makes sense but if using that method than the senders are using the ground wire to activate the relay at that point if im not mistaken


ok after doing some reading i understand what your saying about high speed low spend essentially all electrics are high and low speed depending on voltage sent to the fan

but wouldnt you need a voltage regulator to decrease the amount of voltage being sent thru which relay for it to function properly?

[homemade87]

Originally Posted by sev85

makes sense but if using that method than the senders are using the ground wire to activate the relay at that point if im not mistaken


ok after doing some reading i understand what your saying about high speed low spend essentially all electrics are high and low speed depending on voltage sent to the fan

but wouldnt you need a voltage regulator to decrease the amount of voltage being sent thru which relay for it to function properly?

No need to do anything special on low speed .On 12v you can run the fans in series to run them half speed . ( basically 6 volt to each fan in series = half speed ) . The relays do this for you. This is the reason for the three relays .

You are correct in triggering the relays with ground . You can trigger relays either way . Does not matter . Just have to wire accordingly .

If you decide to order the relay kit listed above it will come with the wire instructions . Just follow the instructions closely and you will not have any problems .

[piecesparts]

Originally Posted by sev85

the alternator is supposed to be a 80 or 90 amp i will double check it when the sun comes up but im wiring the fans to pull power from a relay not from the controller which im still waiting for to come in the mail because none of my local parts stores carried one anyone suggested using so i had to order from online

i lucked into the aluminum radiator which used to cool my 355 nicely but since upgrading to the 400 the stock fan it came with was destroyed so i tried a slightly smaller one which was a big mistake which is why im now doing the electric fans and controller sadly being married with a 2 almost 3 year old and a 10 month old has me on a strict budget

but i was thinking about running the fans in series myself because of the massive draw they have and do you run a single controller or 2 individual controllers?

The alternator being 80 or 90 amp is the max that it puts out and that is at an RPM greater than a 1000, where the alternator is energized by it's regulator circuitry. That size of alternator will only put out 35 amps at idle. I purchased my alternator from a company called Tuff Stuff and they have numerous styles that have higher amperage ratings. You do want to run the fans off of a set of relays, so that your power is going directly from the battery to the fan. The controller should only be a lower amp draw circuit in this wiring process. My controller is a single unti that actuates dual fan relays at different temps. There are several brands out there from the electric fan companys that you can reserch.

[sev85]

i appreciate guys my controller i have order is a hayden dual fan controller for two seperate fans and is adjustable from 0-240 degrees it was the only one i could find that went that high and it was actually remarkably cheap

and i have actually heard of tuff stuff from what i understand they make a whole line of custom alternators and thats who im planning on going thru for my alternator when i do my upgrade

[greg64]

A couple of thoughts. First, do you really know how many amps the fans really draw? Some fans I've worked with are overrated on amps and don't really draw as much juice as indicated. Second, when wiring your relays, take the power for the fans directly from the alternator positive terminal, not the battery. The alternator is producing all the power, not the battery. The battery is just for starting, then it too draws power from the alt. Additionally, the wire gauge from the alternator to the starter terminal (then back to the battery) is usually pretty wimpy and would cause a voltage drop to the fans.

On my suburban's dual fans, I also have a self-resetting circuit breaker between the alt and relays. A dead short with these high capacity alternators would almost certainly melt insulation, and possibly lead to a fire.

[piecesparts]

Greg has pointed out some interesting information, however, you may not want to load up your alternator positive terminal with numerous wires. What I would suggest, is to upgrade the iwre from the positive termianl to a larger gauge and then take it to one of the bolts on your pictured terminal boards, then branch off of that to the battery path and the fans. I did not go that route completely on my truck, I did however, change out my wire from the alternator and I have not had any issues with loading the fans and other heavy amp loads on the truck.

[sev85]

its awesome you guys bring this up because thats half the reason im installing the junction blocks is to upgrade the wiring from the alternator i was reading one of the write ups here on it where the gentleman upgraded the wiring from the alternator to keep from heavy loads causing issues i just took it one step further and decided to add in these junction blocks for easier access to tie into

also greg thats a great idea on the circuit breakers i forgot all about even having a drawer in my tool box full of them

only real information i know about these electric fans is when i ran the part number it gave a estimated starting amp of 30 and a continuous running estimated amp of 5

note the word estimated!?!?!?!?!?!?!?! anyway so i figured upgrade alternator upgrade wiring add the junction blocks and a relay block to be safer than sorry

i spent 20 years trying to get this truck now that i got it i want it done right if it takes me another 20 years to get it done

[Bigstevex4]

With a 180 Stat How does the secound fan cool it to 140?

[sev85]

simple the fans were powered by a jumper wire and ran constantly while it was idling

[Bigstevex4]

There should be no water circulating in radiator under 180 wouldnt matter 10 fans or no fans if stat was working right. Or gauge isnt ver accurate.

[sev85]

all are possibilities which is why im gonna replace all the gauges in the truck with the autometer conversion when i get the chance but the tstate is brand new

[sev85]

But a tstat a tstat opens slowly until opened fully for full flow so unless the blocks ice cold there's always some kind of flow and even then I think it bleeds off to the heater core and back to the radiator

[sev85]

Has to because a belt driven water pump is always pumping the minute the motor is turning over

[piecesparts]

Originally Posted by sev85

its awesome you guys bring this up because thats half the reason im installing the junction blocks is to upgrade the wiring from the alternator i was reading one of the write ups here on it where the gentleman upgraded the wiring from the alternator to keep from heavy loads causing issues i just took it one step further and decided to add in these junction blocks for easier access to tie into

also greg thats a great idea on the circuit breakers i forgot all about even having a drawer in my tool box full of them

only real information i know about these electric fans is when i ran the part number it gave a estimated starting amp of 30 and a continuous running estimated amp of 5

note the word estimated!?!?!?!?!?!?!?! anyway so i figured upgrade alternator upgrade wiring add the junction blocks and a relay block to be safer than sorry

i spent 20 years trying to get this truck now that i got it i want it done right if it takes me another 20 years to get it done

This is how I did one of my trucks.