Budget electric fan, thermal switch for SBC challenge engine

I've been planning on using the clutch fan that came with one of the engines I have on my Challenge Elky's 350 SBC. But after reading through some of the recent discussions on the forums and talking with some more experienced engine-builders, I've decided that it would be better to switch over to using an electric fan setup instead. Since A) this is a Challenge car and B) this wasn't something I've been planning for in the budget, I'm hoping to grab the parts to make it happen from the local junkyard. I will likely be getting a very cheap fan from a fellow GRMer, but I like having options, and will still need to get it all wired up and working smartly.

I figure I need the following parts to make a nicely functioning electric fan setup:

Fan Shroud (hopefully comes with the fan, but may not work with the engine...) Thermal switch Relay Toggle switch (the Challenge IS a race, so I want to be able to shut it off on command)

The relay should be easy- I can just grab a standard automotive relay out of anything I can find one in. Likewise with the toggle switch for it. Which mainly leaves the fan & themal switch.

Any suggestions as to vehicles that I should be zeroing in on in the junkyard to hopefully find a fan that will handle cooling a small-block 350, and a thermal switch to control it? Thanks!

Taurus fans are very popular, I'm going to be doing something similar on my small block for the tow vehicle. I run toggles on the race car but something like that I would want to be automatic, I've heard DSMs have one that is easily used but I'm unsure on the details or reality of it.

I wonder if you even need a fan. Autocross runs are short, and you get plenty of airflow during drag runs. You could probably get away with warming the engine up and pushing the car to the autox start line. Fire it up and go, pop the hood and let it cool awhile between runs.

Yep, do some measuring of the radiator area you've got to work with and then hit the yards with a measuring tape to find a fan/shroud that are close.

To actuate the fan, look at early VW/Audi's, etc they have a thermoswitch on the radiator that simply turns the fan on and off based on the temperature. Mount the switch in the path of the coolant, connect the fan's ground to ground and the power lead to one side of the switch and 12V power to the other side of the switch. If you want to get fancy you can run the fan via relay by using the thermoswitch to activate the relay.

Older Subarus have a thermoswitch too, and an electric fan assembly with a bracket that lends itself very well to repurposing.

The answer is always Miata: on the 90-93s, there's a thermoswitch in the coolant neck at the front of the head. When warm, switch connects the contact to ground (or more correctly, to whatever it's threaded into).

Alan Cesar wrote: I wonder if you even need a fan. Autocross runs are short, and you get plenty of airflow during drag runs. You could probably get away with warming the engine up and pushing the car to the autox start line. Fire it up and go, pop the hood and let it cool awhile between runs.

While the car is being built for the Challenge, it is also going to be driven normally for a while before (and after, but then I could get a nicer fan if necessary...) as well as being driven down to the Challenge- so it does need a fan in general.

Now... it is true though that I could pull the fan OFF for the Challenge itself so it didn't count in my budget (and I will be doing this with the stereo & such for the drive down and back...), but if I can get the parts for $20 or so, there's no real reason not to just have it in the budget.

Cool, lots of good ideas. And I know there's at least one Miata in the yard here in town. Not so sure about Subies, but there are a few VWs as well.

Older Mercedes have a hell of an electric pusher fan. Can be a challenge to have enough spare current to power it though.

$20 plus shipping.

For all the effort and used parts, there are such cheap fans out there these days you can get new slim-line fan(s) with thermo switches in kits for chump change shipped to your door.

Example 1

Are these as good as OEM, probably not, but you don't have to go through any hassle, it will probably cost you the same as far as $$, take less time since it's all packaged together, and last as long as another 'budget' solution might...

Raze nailed it. I wouldn't use anything else with a new kit for sale so cheaply.

In reply to Raze:

Interesting. Only thing I'd wonder would be if it was possible to get the thermoswitch to turn the fan on at a higher temp... operating temp for a SBC should be closer to 200 from what I've read. That's something to keep in mind if it looks like I've got the room for it in my budget...

http://www.amazon.com/Hayden-Automotive-3651-Adjustable-Thermostatic/dp/B000C39C72/ref=sr_1_5?s=automotive&ie=UTF8&qid=1353011416&sr=1-5&keywords=adjustable+temp+radiator+fan

Pretty cheap really for what you get out of it, and then get whatever fans you want to use, including junkyard units.

Get a used OEM fan, cheap aftermarket ones are junk. Go to your junkyard and find the one that fits your package space the best and looks the highest quality (big diameter, lots of blades, for a higher horsepower engine, etc.) since they're all the same price at the yard. For temp switch, stick with GM. Tons of GMs (including the SBC) come with a fan temp switch that threads into your normal pipe thread ports on the manifold. Don't forget to grab a relay for the fan (the switch is only rated to pull enough current to trigger the relay). No need to turn it off with a toggle...if you get over 220°F on the track, you still want that fan to come on!

Here's a huge list of fan switches in here, if you have a specific pipe thread, temperature, connector, etc. that you're looking for:

http://www.napaechlin.com/upload/NAPAEchlin2/Documents/ECH_NA141_HQr.pdf

Bryce

This looks challenge-budget friendly:

http://www.summitracing.com/parts/hda-3653/overview/

It's adjustable and uses a radiator temperature probe so you don't have to worry about matching pipe sizes or whatnot.

Nashco's right. A junkyard OE fan, unless it's been damaged in a crash, is going to be more durable than a typical cheapo aftermarket unit. OE parts go through durability testing hell. Aftermarket parts not so much. minivans typically have good fans on 'em.

Nashco wrote: Get a used OEM fan, cheap aftermarket ones are junk. Go to your junkyard and find the one that fits your package space the best and looks the highest quality (big diameter, lots of blades, for a higher horsepower engine, etc.) since they're all the same price at the yard. For temp switch, stick with GM. Tons of GMs (including the SBC) come with a fan temp switch that threads into your normal pipe thread ports on the manifold. Don't forget to grab a relay for the fan (the switch is only rated to pull enough current to trigger the relay). No need to turn it off with a toggle...if you get over 220°F on the track, you still want that fan to come on! Here's a huge list of fan switches in here, if you have a specific pipe thread, temperature, connector, etc. that you're looking for: http://www.napaechlin.com/upload/NAPAEchlin2/Documents/ECH_NA141_HQr.pdf Bryce

I'm really tempted to waste a bunch of paper at work right now..

Sky_Render wrote: This looks challenge-budget friendly: http://www.summitracing.com/parts/hda-3653/overview/ It's adjustable and uses a radiator temperature probe so you don't have to worry about matching pipe sizes or whatnot.

I'm using that on my Fiat, it's adjustable, has a nice thermo-probe for the radiator, easy to setup and set.

And I agree with the OEM, I even said so in my original post, but for a challenge car, if sizing and cost are the primary drivers, not reliability I'd go with aftermarket and save some hassle (I'm thinking mounts and having the complete kit and such). The best possible solution would be an adjustable switch with a nice OEM fan,,,

i would really recommend against the hayden fan control. i had one melt on me running a pair of fans it said it was rated to run, and it nearly cost me my lsx swap. i found many other similar reviews online.

i have switched to a cheap derale on/off with the probe that touches coolant and replaced their crappy chinese relay with a GM one, and am very pleased with it.

radiator probes suck. probes in coolant passages are good. caravans have fans that fit lots of gm radiators nice. 3rd gen camaros have nice fans with a built in shroud, if you need one cheap i might be able to help.

fidelity101 wrote: I'm really tempted to waste a bunch of paper at work right now..

No need...save it to your computer, then it's searchable!!!

Bryce

Chrysler 300M fan assembly. I can not stress enough how awesome this setup is. It's made to cool a 200+hp V6 in a cramped engine bay with poor air in and no air out. Two two-speed fans, each speed is run on a separate 40 amp circuit. (both fans on each circuit)

On a 200+hp N/A RX-7, with about 3" of uncovered overhang on each side of the radiator, it IS enough to cool the engine in real time. Start a dyno run at 190F and end the run at 180F.

Downside: I have them on 30a fuses and they blow every now and then, and 60 amps of cooling power is enough to just about stall the engine unless I crank the idle up. On the other hand, the car simply does not run hot even at triple-digit temps.

read first post, skipped to bottom:

i used a fan out of a 4 cylinder 86 Celebrity to keep the 400ish hp 355 in my Nova cool. that one was wired to be on whenever the key was in the "run" position. i later used the fan harness and relay (it's all self contained on those cars, really easy to grab the harness complete with a fusible link) with a second relay and a 215 on/210 off thermo switch out of the Echelin catalog at NAPA to activate the dual LT1 Caprice fans in my 74 Monte Carlo... both cars stayed nice and cool- the Nova never got about the 195 thermostat temp and the Monte never got above the 215 degree fan switch temp.

my current 305 powered 86 Camaro keeps cool with the stock V6 fan and wiring activated by a 220 on/215 of Echelin switch in the intake manifold.

Your local parts store will have good radiator probe fan controllers for less than $20

I have had great luck with 2 speed fans from tauris / sables. I have wired them in many ways. But my usually way is to put a three way toggle switch so up puts the fan on low speed running through a temp sensor. The middle position is low speed on all the time and down is high speed all the time. For endurance racing I some times change the wiring so that the middle is wired to a switch that is controlled via RPMs If the RPMs are less than 2K the fan comes on. This is so that when the car comes in to the pits the cans automatically come on while we are servicing the car. I don't know how many times a car of mine would come to the pits and overheat due to the driver forgetting to turn on the fan's

In reply to dean1484:

That's a great idea (RPM switched fan)