[Chevelle408]

I currently have a stock fan in my '70 and was thinking about upgrading to a dual electric fan setup. What kind of power/performance increase can be expected from this? Also, what are the pros and cons of electric fans?

 

[chev-hell]

pro's

it'll cool nearly anything
don't have to worry about chopping off your fingers
save HP
looks cool
if 1 fan fails the other will help
a/c works better in stop-go and cooling is better
full air-flow at low rpm's or at idle

con's
upgrade alternator cost
it's electric so it "could" fail
either way i'd do it any day of the week over a mechanical fan

 

[ALUMITECH REPRODUCTIONS]

Zack
There will be different opinions on this subject ... some people will insist on a 7 blade clutch fan ...but as you asked here is some info
just my .02
pros
City traffic where CFM draw is low with a mechanical fan the electric fan will do its job Spal twin 11 inch .. for instance
2800 CFM while sitting in traffic cools things down with in 1 min .. operated off a 195 degree sensor it knows when things are getting warm ...as a mechanical fan cant compare .
Keep in mind the more CFM you can put trough the radiator the higher the the cooling effect.

yes you will save some h/p not huge but a savings none the less.

as far as electrical systems go , your drawing off the battery yes and in most the casses the fan wont run for long periods so there may be no need to up grade the alternator .

if you don’t mind losing stock looks in the engine bay ... this set up will eliminate the mechanical fan and fan shroud .. cleans things up a bit .

Spal makes a nice unit with 6 rubber doors that open at cruse and highway speeds to allow more air flow ... not all manufactures offer this neat innovation .

Alumitech offers this unit with engineered brackets to fit Harrison brass copper rads along with our aluminum units .

here's a link to photos
http://www.chevellecooling.com/m3.html?form_name=ecom_ecl_product_details

http://www.chevellecooling.com/m3.html?form_name=ecom_ecl_product_details

Don

 

[HOTRODSRJ]

as far as electrical systems go , your drawing off the battery yes and in most the casses the fan wont run for long periods so there may be no need to up grade the alternator .

Don

I have to take exception to this with the highest respect to Don. Don provides great advice to many on this subject, but I offer this different take....

It's obvious that you want as much air flow as you can muster for both airconditioning (if you have it) and engine cooling....and at high cruising speeds fans usually are not needed at all to aid and abet the airflow thru the radiators. However, these big cooling fans can commonly take in excess of 30 amps and some as high as 40 amps plus. While it might be easy to think that these fans only run intermittantly at low speeds, alot of these cars spend most of their lives at low speeds and idle conditions....in very hot conditions and the fans run a lot! This is typical at large car show events where street cruising and long traffic lines are the rule...and not the exception. Even in everyday driving situations. Most fan systems can run 75% of the time in normal cooling applications believe it or not.

Don is correct, when you don't have enough electrical output from the alternator the excess demand calls on the battery to provide extra amperage/wattage to fill the gap. This IS what a battery is obviously for. But, when you get to the point where the demand is most of the time or even alot less than that, the battery becomes discharged all the time with no "charging buffer" for the system to ever fully recover. This commonly produces low DC bus voltages which leads to dim lights and questionable restarting conditions...especially when the engine gets hot further making starting difficult. Low DC bus voltage also leads to inaccurate gauge readings (because this voltage is used for reference in most gauges) and of course the cooling fans themselves are "derated" due to the low voltage....meaning less airflow.

To complicate all this, the "rating" system for alternators are at PEAK output which occurs at highway rpms....so commonly a claimed "63amp" alternator only produces 50% of the rating at low and even moderate speeds. Even the most simple of automotive electrical applications can demand as much as 35 amps most of the time....and that's just for lights, a moderate stereo, ignition and throw in a blower motor once in awhile. So you can see how you can get into trouble real fast and/or how narrow the "charging margin" is without a sufficient output from the alternator, ....then add a 30+amp fan. Well, you get the picture...

So, assuming you want to build a system for the "peak demand" of the conditions one would expect, you have to upgrade your electrical system in the wiring department and higher output alternators. With the proliferation of electrical components these days....the "100" amp alternators are very common and reasonably priced. The "high ouput" series such as the CoolCharger series from TuffStuff will provide as much as 80 amps at idle....more than enough for this type of upgrade.

Also, pay attention to the DC bus/wiring when upgrading the alternator. You can easily pop a fusible link and/or burn up a feeder or connection with increases in amperage thru these connections.

I hope some of this sinks in and provides some insight to why one wants to upgrade the electrical system as well.

 

[LeoP]

Always good info and reading from you Steve. Thanks

 

[Phil Keller]

Just got a '67 Chevelle with electric fans. After reading these posts, I'm going to upgrade the alternator. Thanks for the great info to all.

 

[Chevelle408]

Thanks, this really helps.

 

[chev-hell]

You have a 70 too.... the windstar fans are great, and add the alumatech radiator and my new big block (572hp) hasn't run over 180* yet, the 2nd fan hasn't even come on yet after a few weeks of driving..

 

[ALUMITECH REPRODUCTIONS]

Intersting package ... I like the way this set up looks and works with the long water pump on a big block .. seems the windstar fan fits our rad very well ...what CFM RATING is the unit ??
Don

 

[ALUMITECH REPRODUCTIONS]

Always Good to hear from Steve ... he always seems to bring out things that most of us havent heard before ... as in the case that alt only put out 50% at normal driving and only 100% at peak ... interesting facts thanks again Steve.

I was only going off results customers have given me ...we did a install on a 700 hp car ... and at a cruz in Detroit 10 miles of stop and go he clams the fans only came on 3 times for 30 seconds each cycle .

 

[Xplantdad]

Don you have a PM...

 

[Sgtpop]

I also installed the twin fan system. I took my alt to a friend who rebuilt it to a 110amp. I then got a heavy duty volt reg. I did not want to change to a 1 wire alt. I know from experience if you dont change the volt reg after up grading the alt it will smoke it. Yes there are pros and cons. Mine runs 185 in the hot summer months in the south. I have both fans wired to come on at the same time. I also have a switch under the dash that I can manually turn them on anytime. If youve got air they can be wired to have one come on and then the other. As mentioned above always check your existing wiring before proceeding. This system has worked well for me.

 

[Rowdy]

www.4alterstart.com part # 7122-3-135a-SP Standard external voltage regulator case rated 135 amp.

I ran across this company on eBay last April, ordered one direct (no bidding) for $79.99
Worked great, plenty of power for fans and anything else you want to turn on.
Sgtpop is absolutely correct, you'll fry your regulator, and/or an inadequate fusible link within days if they aren't up to snuff.

Rowdy

 

[dittoz]

...and no heater hoses to boot! Boy, plugging those off sure cleans it up in there!

You have a 70 too.... the windstar fans are great, and add the alumatech radiator and my new big block (572hp) hasn't run over 180* yet, the 2nd fan hasn't even come on yet after a few weeks of driving..

 

[Motorhead62]

The upgrade is worth the effort. My Chevelle will run 170 degrees in traffic in the Texas summer heat. Enough said!

 

[chev-hell]

...and no heater hoses to boot! Boy, plugging those off sure cleans it up in there!

yep, and when i changed to a STOCK water pump, i plugged it too, same thing, 175 all day long, that's with just the 1 fan running, but also notice my nice ALUMATECH radiator
OH< HERE'S THE NEW impoved ENGINE and stock pump i now have....