If I put electric fans on to reduce engine drag I have to use a 100 amp alternator. Does a 100 amp alt. create more drag than a stock 40 amp alt? If so then I'm decreasing water pump drag but increasing alt. drag. I still have the engine drag, it's just on a different accessory. Am I missing something in my theory? Thanks

68 Vetteman

 

Are you sure you have to have a 100 amp alt? I don't think I do but will check again ... I have the "Be Cool" radiator and dual fan set up ...

 

IF the fans are running, and you are at idle or very slo speed, you have a load on the alternator, if you running 40+ mph, the fans are not presenting any load to the alt, as the blades are being spun by the inrushing air....

and yes, any load on the alt will be translated into load on the belt/engine...of course....

But the capability of the alt for handling load does NOT mean it is there full time....IF the load on the alt is only 40 amps....at 14 volts, you multiply those and get 560 watts....748 is ONE horsepower....

 

I added 2 amps for speakers. When the car sets between drives the amp gage is at 40 amps till the battery is fully charged.

 

There's no free lunch, the alternator will only charge (use horsepower) when it's called for. There is a slight horsepower gain by switching to electric fans, hardly measurable from what I understand.

 

Nope, you've got it right. Good for you!

 

The other thing I'm thinking of is one of the light weight performance engine fans. I don't have any overheating issues and replacing the stock fan with a lighter fan would decrease drag. I could also use a smaller dia. crank pulley. Easier to install too!!
68 Vetteman

 

Electric fars are the way to go....

 

Oh, bad, bad. And you did so well on the first go round.

The weight (mass) of a fan is almost irrelevant and only makes a difference during acceleration (inertia). The drag of a fan is unrelated to it's weight all things being equal. Stock fans only consume significant amounts pf power when the clutch engages, and they engage because it's time to cool the engine. The maximum amount of power consumed at red line would be hard to notice and is exponentially less at lower engine speeds.

A smaller crank pulley would slow down all the accessories including the water pump. Why would you want to do that?

 

I have them on my 406 and
they work great also have 2 amps and a
cs144 alternator 140 amp

 

Electric fans are fine. They are more reliable (no belt to break), but they will absorb the same amount of energy (or very close to the same amount) as a belt-driven fan, assuming that it takes "X" amount of work to move the air needed to cool the engine properly. As mentioned, "no free lunch". Of course, you DO have to pay for the fans and the conversion work...the belt-driven one on the car is already paid for.

 

The thing that scares me is that my amp gage shows a 40 amp charging rate. As I drive a while the rate goes down. With a 100 amp alt. do I need a new amp gage and wiring? The original wiring scares me. Thanks
68 Vetteman

 

probably need to run a seperate wire from the alternator straight to the fans circuit breakers /relays. bypass the amp gauge and factory wiring. that way the power to the fans is supplied by the alternator directly and not the battery while the eng. is running and you wont see that high amp charge rate.

 

I tried running Spal electric fans with the stock 40 amp alternator and it was to much of a drain. The radio would shut off and the lights would dim when the fans would come on. I had a 100 amp alternator so dropped that in taking the pulley from the 40 amp and putting it on the 100 amp. That 100 amp works great and no need for anymore.

 

This always starts a huge flame type thing everyone wanting to get in their 2 cents on electric vs belt or which electric is best, but electric fans especially factory ones like the Ford Taurus are light years beyond the designs of the 50 plus year old belt driven fans on C3's,
Even more modern belt fans were better than old antique belt fan designs,
So in that, the modern electric wins over the antique belt fan...and very well is more efficient,
The only "free ride" so to speak in cooling is after about 30 MPH when flow should cool the engine with no fan at all....but you still have to pump the water thru the cooling system,.
Then in my looking for tests on electric it's almost impossible to find non biased information,
When someone or a company pays a lab to test fans why is it that the way the person who pays wants the results to turn out IS how the results always turn out?
Pretty much all modern production cars use electric fans and not because they are cheaper ( they are not ) but because they do a more efficient job in a more efficient way,
Many times a person will hail this or that cooling system as being the end all to be all when the real case is they replaced old trash parts not working well with new modern working parts.

At the moment I run a 105 amp alt with my taurus fans, low is about 180 high which I seldom see is around 200-205,
When weather starts getting warmer I will get a new radiator and while ******* is top on my list I am still researching that.

 

There is no need to bypass the ammeter because of increased current flow. That current does NOT pass through the meter...it only passes through the main power line feeding the battery. And the only wiring that would need to be changed is any segment that is carrying significantly higher current than the original wiring was meant to do.

Depending on how you wire your fans into the system, that might mean "paralleling" a line with additional wire to handle increased current and also increasing the size of any fusible links that are in that modified wiring circuit.

Remember that the 100 amp alternator will try to send 100amps to the battery, if the battery is severly discharged. Under normal circumstances that high charge rate won't happen. But, if the battery is weak, or if the battery gets run down [for whatever reason], that higher charge rate could fry the existing fusible link and leave you stranded.

 

I have dual spals on a '69 350 with about 400 HP and a stock rad. and alt.
No problem with insufficent current(lights stay bright) and it has never gotten above 180 degrees.
You must however use relays for the fans and the headlights. I have relays for all circuits that require a full 12 volts that must go thru a switch.

 

Isn't that the pot calling the kettle black? It's fine to say one is better than the other (ie tastes great/less filling) but explaining how and why is another.

The 'electric is better' argument is always predicated on 'conventional' style fans consuming huge amount of power all the time (false) and conveniently overlooks the transfered load put upon the alternator (oops). Net gain is pretty well zero in the real world.

The same smoke and mirrors act goes on the with the Chevy Volt and the claims that it gets over 200MPG.

 

If you engine is running cool already no need to look at any other kind of fans. The electric ones can help some as they run at a Constance speed when running around town as opposed to the engine driven fans. But that is all there is to them, not really better at all because most times they draw more power than the engine ones, the factory's started using electric fan not for efficiently or anything else except most all were going to sideways mounted engines! But if power is the name of your game a electric water pump as well as fans is good as you can turn them off for no load until your 1/4 mile pass is done!

 

Thanks for all the advice guys but I'm still confused (and not afraid to admit it). If the current doesn't flow through the amp gage how can it show if the battery is charging or discharging? The way it sounds the only wiring that has to be changed is the power lead that comes off the alternator. Is this the wire that is connected to the starter with the power wire that connects to the battery? Again thanks a lot. Electrical is not my strong point.
68 Vetteman