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Old 05-29-2005, 06:00 PM
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Electric Fan Recommendations?

Hey guys, me and my dad are about to rebuild the engine in my '73 Malibu 4-Door. It's got a built 350 sbc but still has the stock belt-driven fan.

I currently drive an '83 Buick Skylark and that's got an electric fan. I really like that because it's off until you need it, not taking up precious horsepower. I've also heard that you can gain up to 10 more horsepower by switching to an electric fan.

Could you guys recommend something for me? I think we want to go with a dual fan setup i.e. two fans in one unit type thing. Is that wise? what's the best setup?

I know you want to match the electric fan's CFM to the CFM that the belt fan pushes, lest you overheat your engine.

So could I have your assisstance please? Thank you.

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Old 05-29-2005, 07:03 PM
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Dual fans usually will do the trick, but you will need to upgrade your old 55 amp alternator to handle the load. Some duals pull up to 35 amps!! You can get the same size 7127 alternator but in the 85 amp version. Part number is 7137 and looks the same except it has a black plastic fan on it instead of the metal fan.

Spal makes excellent fans and has a dual with a shroud but they are pretty pricey, specially when you add in the thermostat and harnesses. Not sure if it would really be cost effective on an older car.
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Old 05-29-2005, 07:12 PM
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If you already have the shroud and fan in place, use it. Fan thermostatic clutches don't use horsepower until they tighten up and spin the fan.

If you're determined to use an electric fan, the dual setups with a full shroud work the best. Spal, Flexalite, etc... they all work fine.

Larry
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Old 05-29-2005, 07:26 PM
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Fans

Doc here,

Agree with Coldknock...

If you really want the extra horses, leave the spare, and trunk junk at home..run it on a 1/4 tank of fuel...It will amount to about the same gains...For a LOT less money..

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Old 05-29-2005, 07:39 PM
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Stewart Water pumps (supplys Nascar high flow water pumps as well as to enthusiasts) recommends a high quality fan clutch with a five or six blade fan to cool your engine. I wish I could remember the number they state, but the number of horses you lose with said fan is greatly exaggerated. I run one of their water pumps with a good fan clutch and have no problems whatsoever in a small block camaro pushing 400 ponies. Remember, the OEM's went to electric fans due to ever shrinking underhood clearances, not for performance reasons
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Old 05-29-2005, 10:58 PM
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So let me get this straight. You're saying that the belt driven fan on there right now doesn't spin until the clutch is engaged? I see it spinning all the time....
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Old 05-30-2005, 01:38 PM
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electric now days really is the way to go.if you don't want to do any extra work jegs has a dual 10" or 12" flexalite fan for slightly more than 200.00.if you don't mind the extra work you can go to the junk yards and get any number of very good fans off of newer compact and imports or cadilacs and make your own dual 10,12,13,14,15" setup for about 25.00 per fan and there are some nice ones out there.you just have to be willing to do the leg work.you can mount them individually or make a dual set-up out of a piece of sheet metal.you can have them come on one at a time or run both.lots of possibilies and it leaves you the money to get your upgraded alt..
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Old 05-30-2005, 03:23 PM
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Well I found out some inforumation today and I will be sticking with the belt driven fan.

My dad replaced the stock fan with a flex fan which straightens out the faster it spins. We do not have the clutch mechanism because he says they wear out, then your screwed.

So this flex fan supposedly is stressful on a motor than the stock fan.
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Old 05-30-2005, 03:50 PM
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Personally, I don't like flex fans. They are ok at low to med rpms, but when you wind them up they are very noisy and take an enormous amount of power to spin them up. They go flat because they are pushing air. Even when they "look" flat, they are still pushing air and eating up hp. On top of that, I don't trust them to not come apart at high rpms. Seen some stock ford flex fans pitch a blade. Not a good thing.

My suggestion is if you are in a normal climate use the elect. fans.
If you are in a hot climate and have AC, use GOOD elect fans or the stock steel fan WITH a good quality fan clutch.

Quote:
Originally Posted by Malibu73
So let me get this straight. You're saying that the belt driven fan on there right now doesn't spin until the clutch is engaged? I see it spinning all the time....
If the fan clutch is working correctly, it will SLOWLY rotate the fan when the engine is running. When it senses high temps, it engages and spins up the fan to cool the radiator. Once the temp comes down, the clutch unloads and the fan will slow down. It never stops until you shut down the engine.
Also, most good clutches will give up around 2500 rpm because you really don't need all that air flow when you're cruising down the road at 50+ mph.

Mark
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Old 05-30-2005, 05:45 PM
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I love the simplicity of a clutch fan combined with a fan shroud. Good, effective and dependable. If you go the electric fan route, then you must get a twin fan set up and have to ensure (as mentioned) your alternator output is higher the the fan current draw. You also have to put up with high noise level normaly associated with elec' fans. If I were to go electric, I'd fit the twin fan set up from a Taurus but would have it run a 2 speed system. Slow speed fan control for normal cooling and then high speed fan control for extreme radiator heat removal situations. This would ensure current draw is minimal most of the time and also reduces noise to a minimum. I'm not sure where you can get a 2 speed fan controller but i think u can download a circuit diagram from somewhere on the net that you can knock up in kit form
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Old 05-30-2005, 06:01 PM
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Fans

Doc here,

Also be advised in addition to installing a higher capacity Alternator, You MUST install series wired duel (or for 2 fans) Quad relays...and upgrade the wiring (from 18 ga to 10 gauge) to meet the demand of the fan draw, a Set of fuse links or fuses, else suffer the possibility of a harness meltdown and Vehicle fire.

You will also have to install a thermal switch at the radiator, manifold or in the hose..If it is to be automatically controlled...and If not, a dash switch to the relay control circuit.

You simply can't throw a set of fans in and call it all good...Or if you do...then one upgrade is totally required...your fire insurance!

Doc
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Old 05-30-2005, 06:55 PM
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ye, that's right doc............only someone with a sound knowledge of electricity should carry out any such operation.
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Old 05-30-2005, 09:30 PM
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Aint nothin that butt connectors, speaker wire and duct tape can't handle!!!
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Old 05-30-2005, 11:15 PM
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Speaker wire? Yeah, your insurance would well and truly need to be fully covered for fire and stupidity!
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Old 05-31-2005, 02:34 AM
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Wire jobs..

Quote:
Originally Posted by Jmark
Aint nothin that butt connectors, speaker wire and duct tape can't handle!!!
Doc here,

LOL.. I have , over the years, run across a few Mac Giver Marvels wired in this fashion... :noon:

At least they were Before the installation of a new Painless harness..scraping of melted poly~Vinyl~Chloride from the engine...body...interior parts and repaint of the "Black Spots " in the finish going down the left side..

One Sure thing...Once you let the Smoke escape From the wires..it causes all kinds of body / Interior damage!

Doc
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