electric fans
Pro
Joined: Jun 2007
Posts: 634
Likes: 0
From: Hastings MN
So call it 40A*12V = 480W.
I read on wikipedia that automotive alternators are 50-60% efficient, so take worst case and it's 50%. That doubles our draw on the engine up to 960W. Divide by 746W/hp.... = 1.3hp. (Instead of say 10? That's a huge improvement, when in all reality we were actually just trying to get better cooling and clean up the engine bay a little!)
I read on wikipedia that automotive alternators are 50-60% efficient, so take worst case and it's 50%. That doubles our draw on the engine up to 960W. Divide by 746W/hp.... = 1.3hp. (Instead of say 10? That's a huge improvement, when in all reality we were actually just trying to get better cooling and clean up the engine bay a little!)
Melting Slicks
Joined: May 2007
Posts: 3,246
Likes: 4
From: Bay Area CA
Yeah, I fabbed some small tab like feet to slide into the bottom channel of the core support in front of the radiator. I then added pads between the fan and the radiator, and for the pic I just zip tied it up. It's been so cold I haven't had a chance to fabricate my upper bracket yet but I will use aluminum angle iron to make my upper brackets.
Team Owner
Joined: Aug 2006
Posts: 24,125
Likes: 15
From: Columbia Missouri
Racer
Joined: Sep 2007
Posts: 253
Likes: 0
From: Pearlington Mississippi
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Race Director
Joined: Dec 2007
Posts: 14,345
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From: Hartselle AL
St. Jude Donor '09
I went with the Mark VIII setup. gets up to about 210 or so until the stat opens up then I go just barely over 200. I think I got a switch that stabs into the radiator from pep boys ( not for sure where I got it though). of course a relay.
Durango, you just ran a wire from the relay to a thermostat? So the hotter the engine gets the faster the fan spins? I like that better than the radiator probe, but I don't think the mark VIII is variable, only 2 speed
Durango, you just ran a wire from the relay to a thermostat? So the hotter the engine gets the faster the fan spins? I like that better than the radiator probe, but I don't think the mark VIII is variable, only 2 speed
There are several Mark VIIIs and Taurus fans on flea-bay at the moment at ridiculous low prices.
Team Owner
Joined: Aug 2006
Posts: 24,125
Likes: 15
From: Columbia Missouri
Yep, in fact I have a Taurus fan I am not going to use since I upgraded to the Focus fans.
Race Director
Joined: Dec 2007
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From: Hartselle AL
St. Jude Donor '09
Team Owner
Joined: Jul 2004
Posts: 40,408
Likes: 792
From: Redondo Beach, California
In addition to all the other benefits of an electric fan mentioned above, I find another great advantage being than you can work on the engine with the engine running and not worry about being hit by the fan. Particularly trying to hold a timeing light up close to the engine crankshaft damper and not worring about sticking the light or your fingers into fan. Also, if the engine is hot, you don't have to work with a great blast of air. You can always temporarily turn off the fan.
Instructor
Joined: Sep 2006
Posts: 142
Likes: 1
I think the fan cost me $50 on eBay and maybe $40 for the probe and already had a relay.
I ran with the factory 70 amp for the longest time and it ran ok but sometimes could feel a bog when the fan kicked on. I JUST upgraded last weekend to a 140amp cs144 alt that I bought from a member on the forum for $50 (which reminds me I need to reply and let him know I received it and it's running great.) It was really easy, same size and mounting. Just had to run to the parts store to buy the proper plug adapter and wire it in place of the old one.
Drifting
Joined: Aug 2000
Posts: 1,758
Likes: 4
From: Medford, Or
http://www.vetteworksonline.com/radi...olant_fans.htm
www.vetteworksonline.com
Last edited by vettedan; Feb 21, 2008 at 12:41 AM.
Burning Brakes
Joined: Mar 2005
Posts: 1,139
Likes: 0
From: Salina Kansas
I went the dual Spal route last fall, it works, but haven't driven it in the heat enough to know if I have any problems. Just have the stock 4-core brass radiator in it and it's controlled by the FAST XFI computer and a couple of 30A relays.
Drifting
Joined: Nov 2003
Posts: 1,634
Likes: 4
From: Northern NJ
St. Jude Donor '04 & '05
I too went the dual spal route a couple years back. Mounted fairly easily using a few brackets made from flat bar at the top and a couple short straight pieces at the bottom using the lower shroud mounting bolts as the attachment point.
Power was tapped from the back of the alternator thru a 30 amp relay and fuse for each fan. For now I'm just using a simple thermo switch sensor to turn on/off both relays/fans together which seems to work fine. However I did wire each fan w/it's own line/relay/fuse so I could power them on at different temps if so desired in the future. FWIW.
Good Luck!
Melting Slicks
Joined: May 2002
Posts: 2,717
Likes: 121
From: Sulphur LA
St. Jude Donor '05-'06,'11,'13-'14,'16,'18,'19,'24, '25
most fans are rated with no radiator in front of them for the cfm rateings (per Tom D.). The radiator is a restriction for the fan, adding a pusher infront of the radiator to help will increase the flow through the radiator (pressure drop across the radiator). I added two fans in front of mine and I can watch the temp drop when I turn them on in addition to the puller fan I have. I thought I read were the 80 to 82 c3 had the pusher fans added for those years.
Neal
Neal
Race Director
Joined: Dec 2007
Posts: 14,345
Likes: 4
From: Hartselle AL
St. Jude Donor '09
If you tap into the alternator for the power source, do you not lose fan cooling after you shut down the engine? Have been told by a good mechanic that residual heat after shutdown can be just as hard on an engine. That being said though, it is obviously what occurs with a mechanical fan.
Team Owner
Joined: Aug 2006
Posts: 24,125
Likes: 15
From: Columbia Missouri
If you tap into the alternator for the power source, do you not lose fan cooling after you shut down the engine? Have been told by a good mechanic that residual heat after shutdown can be just as hard on an engine. That being said though, it is obviously what occurs with a mechanical fan.
Two things to this. First, it's a myth. How many decades did cars have mechanical fans? Even up into the late '90's. When you shut down, no fluid or air is circulating. I don't recall any heat failures with my Durango, it's mechanical fan, or it's 150K HARD miles.
On the other side, so what if the fan continues to pull air through the radiator, the water pump is mechanical and no fluid will be circulating through the engine or radiator.
Basically, a run-after electric fan will do two things. It will cool the radiator down so your next start up comes with an influx of cool fluid, AND it'll draw cooler air into the engine compartment.
Anyone who has tried this knows that blowing an external fan on a hot engine doesn't do much for it. The run-after feature is not something I would consider unless you have a run-after electric water pump too.