Check this out-nice little 2-speed fan harness...

[HEI451]

Just food for thought, I own a 1972 Chevy Vega, has nice rear end, T5 world class 5 speed, power steering, power 4 wheel disk brakes, A/C, tilt wheel, and a highly modified Rover 4.6 all aluminum V8 that is both bored and stroked to 311 cu/in. It started with a Buick all aluminum .030 over 215. It also started with dual electric fans, as I firmly believed at that time, there was NO room for an engine driven fan, let alone one mounted to a fan clutch of any kind (radiator was literally 1 inch from the water pump shaft stub). Original build on this car was in 1977.

The Buick engine ran a 200 horsepower Skylark AFB carb for its first 5 years, then a Holley 670 cfm throttle body Pro-Jection system, Rover uses a made up tuned port EFI, combination of Rover, Mustang and Holley parts. Both these engines really like operating at 192 to 195 degrees temp. ANYTHING higher, and they suffer badly in all respects. From the start, it ran 230/240 degrees with the electric fans, custom shroud, all the electric fan con job hype stuff correct and in place.

One day in 1979, I ran across a pancake water pump, A/C fan clutch and fan from a new Buick wreck. I got those pieces, and built a full shroud, installed the pump, fan/clutch and shroud. I reinstalled the same anti-freeze, as it was brand new. I removed both electric fans in the process, then ran it up to test.

I sat in it and watched the temp gauge, went to 195 degrees, and stopped in its tracks, correct temp for the thermostat that has always been n it. I then used my infrared temp sensor gun to read the water temps for the hoses and radiator. Upper hose, 194 deg, lower hose, 190 deg, radiator, top, 195 deg, bottom, 190 deg. I then drove it, temp, even with the A/C on, 195 deg as seen on the accurate manual temp gauge n the car.

The Buick engine ran for 23 years, then, it went into another car, full resto of a 1963 Buick Skylark, went back to the stock 200 horse manifold and carb. I built the stroker/big bore Rover next, 10.00:1 c/r, Crower cam, 305 Chevy pistons and early small journal small block CAT H beam rods, Leyland P76 stroker crank (.600 stroke increase), 300 Buick heads, Latest Corvair big valves, same 215 headers and original X pipe I built back in 1985. New bigger engine uses the same fan/clutch, shroud, and even with the A/C on, it still runs at 195 degrees, anywhere, stopped idling, or at speed. This bigger engine has more than 45,000 miles on it since I put it in, and same cooling system as always, and it works well. I KNOW it would also over heat if it was left to rely on an electric fan.

The fan clutch and fan are still about an inch and a half away from the radiator, doesn't seem to be a problem.

I am going to drive this car to Gardnerville, 155 mile round trip, Saturday, and I expect NO heating issues, even in the 100 plus degree day.

As far as the original poster goes, what results have you come up with using the electric fan as you built it? I am very interested, as we all are, as to what the end result is.

[oldspowered67C10]

Heres some food for thought. There is alot of newer cars coming with electric power steering for fuel efficiency. Why run a power steering pump all the time when you only need it sometimes? Kind of a similar situation as the fans, why spin a fan while running down the freeway(even with a fan clutch) when you have no need for it.

The reason most people have better luck with mechanical set-ups is because they're using a OEM engineered fan/radiator/shroud set-up while most people running electrics have a system that isn't really engineered at all. A properly sized electric fan in a properly engineered shroud will work just fine but there's some math that needs to be done that most people ignore.

[jhaymon]

well with a clutched fan, if it's working properly, there is no load when up to speed of 30 or more.

hey what olds engine do you have in your truck.ive got a 403 and im having some issues with parts and wiring.

[OneOffStroker]

I also think that $90+ is a bit much to spend on a 2-speed relay. I used a factory unit from a '90s Volvo. It is 2-speed, fairly compact, and a monkey could hook one up. You don't even need to ground it!! I got mine from pick-n-pull for under $5. Guys on other forums have good luck running them even with 70+ amp (startup) fans. They can also be used for headlight relays (Hi/Lo) or any other number of things. Even work as a single relay. I don't have pics now because I'm at work, but a quick google search will give you an idea.

Oh...and quit *****ing about electric vs. mechanical fans. I don't think anyone here cares who gets the last word. They both move air. The End.

[oldspowered67C10]

jhaymon, Its a 400 big block. PM me if you have any questions and Ill try to help.

[HEI451]

jhaymon called it right, Air conditioning fan clutch doesn't run the fan on all the time.

Saving a half horsepower by not turning a fan, or pump, just isn't worth the 10 horsepower loss from dragging a giant ampere alternator along to run that electric stuff.

[jhaymon]

i think this debate needs to in a different sub forum. im not trying to talk anyone out of e-fans. the way i feel is it's your car your money. I do however believe with all the b/s on the net, people think they do something they really dont do.


if we're going to make this about h/p...most of you need to remember, first step is aways the hardest.
and that is, admitting you don't have a race car and this argument doesn't really matter.

[HEI451]

Once again, jhaymon is right square on target.

[big d's red67]

Wow!! just read this post I didn't know there was such a debate on e-fans vs. regular fans.I think some times opinions are given on forum post even when ther not ask for. I put e-fans in my 67 with a stout built 454 and have had no problems with it over heating but I did my research and found what worked best for my set up. My point here is I dont care what anyone says or about the myths on the net, do research on everything you do to your truck and make sure it will work for your application then there should be no problems. No I did not put e-fans on my truck to make more HP's it has enough I just wanted e-fans and thats all that matters.

[gmachinz]

lol...wow-what a debate! lol, well-the first reason I opt for electric fans is not for any HP gain or claim thereof, it was simply to pull more air @ idle through the AC condensor core on older GM muscle cars when one has retro-fitted to R134A. The refrigerant operates at a slightly higher pressure than R12 so since it moves faster through the system, there is less time to pull heat out. So my decision for electric fan sis for improved AC-not any HP claim-although the arguements cans be made but only on an engine you are getting everything out of.

So, yes there are factory style 2-speed fan relays such as the Volvos but how long do you think they'll last? I simply came up with a solution to a fast disappearing option. As for building akit like mine for $10? That'd be an interesting attempt. First, you have to source a sealed 70A relay...not likely to find one under $10 I'd bet. Then you have to find metri-pak style weatherproof connectors and required terminals-again, not likely to find that at NAPA either. Then there's the J1128 spec wiring-again,not a parts store wire either....yep $10 looks like a no-go....sorry. lol

Anyway, I build a lot of relay kits for customers who simply want/need something for a specific project or idea-the Motorcraft 2-speed fans are the best on the market and as of now I have designed a fan harness kit that gives you up to three speeds for use on any DC electric fan motor-not pulse width but three sperate speeds. I'd like to just add that on a lot of older vehicles where mech. fans are common, the damn shrouds are either non-existant or just too damn expensive and if you have to start from scratch anyway, why not go electric? You're also not likely to NOT upgrade your charging system since that too is pretty easy/common these days too....so it comes down to what you want to do.

For the record, I'm building an 86K10 shortbox and I personally hate v-belt setups-they are just a pita-I much prefer swapping to a serpentine setup and while I'm at it, I have already added a Crown Victoria Police Package 2-speed fan and am using one of my 3-speed fan harnesses with it-not using the low speed terminal-just the high, but I can wire it for three speeds on that one lead.