Varying alternator load creates measureable engine load. Example, look at electric hybred vehicles that regen elec upon decelleration, they brake from varyable electric generation.

My L runs (ran & will run again) (2) 25A 2700cfm Efans pulling nearly 700W or 1hp ideally. In reality, on a hot summer day, it can be twice that. Cycle them together and there are some significant (undesireable) spikes/loads occurring. Unwanted alternator operation generates undesireable heat if underhood temp is a concern.

Operating fans above the speed in which they can drive air (mine is 38mph) will cause a restriction in the natural ramair effect, actually reducing the cooling systems capacity. The rotating fans block the incoming ramair and become an obstruction. The faster the vehicle, the more the obstruction. The only time the fans should be on at speed is if there is no ambient source air (as in racing [drafting]), otherwise the fans should remain off above say 40mph (controller should have a safety override for operation for a high overheat condition only).

 

quote:B-Man
With all of that being said, I agree that running e-fans does not make a measureable difference in MPG, as opposed to not running the e-fans.



Indeed, I agree. That's as I’ve been TRYING to point out. The amount of h.p. lost or gained depending on whether the efan is ON or OFF is negligible. Thanks guys

 

Parasitic loss due to alternator driving efans is a single component of several mentioned above. A few horsepower gained from improving the cooling systems efficiency is worth my attention, particullarly with the racing I do.

They all add up, even more so in the hot and sometimes muggy LA summers, where heat is my target for durability & hp gain.

 

Is it just me or are we comparing two totally different things now.

The E-fan mod is designed to free up parasitically lost HP caused by rotating mass and air resistance in the OEM mechanical fan.

I don't think the discussion is HP and MPG differences compared between running and not running the E-fan, but between using a mech fan and using an E-Fan.

Did this comparison derail somewhere?

Herb

 

This is where the derailment occured...

 

I dunno. My friend Robert Francis and I were having a little conversation about the effectiveness of either running the efan or not runing the efan and the differance in h.p and mileage gains from doing so. I thought?
Anyway, have a great Sunday guys.
I think I'll go take some aspirin.

 

Something sounds very wrong with that. I would at least think youre running a little cooler depending on your thermostat etc.

 

To the people that have the flex-a-lite 270 can you still turn the fan on maually say if you were at the strip thanks.

 

I know. I know. Dante needs to take a look at it and figure it out.

 

There are separate inputs on the controller for:

Fan always on (- input)
Fan always off (- input)
AC input signal (- input)
AC input signal (+ input)

Either of the Fan inputs (always on or always off) override ALL other functions of the controller...

 

Thanks B-man.

 

what about rusty 1999 water pumps?

 

I have read the discussion about increased horsepower, gas mileage, and efficiency in general from replacing a belt-driven fan with an E-fan. I have a difficulty with the math. One party to this discussion and a number of companies who produce efans state that conversion to an efan frees 5 to 17 horsepower that can be used to improve the performance of the vehicle. I note that these fans typically draw around 20 to 30 amps, and I say, "Wow! Free power!." Then I start thinking about it. Now, assuming that a belt-driven fan requires around 5 horsepower to move a sufficient amount of air, l can't understand how a 520 watt (30 amps X 14 volts) electric motor can do the same thing. As noted by someone, one horsepower equals about 746 watts, and therefore, 5 horsepower equals about 3,730 watts, and 15 horsepower equals 11,190 watts! Assuming a 30 amp fan does the job, then the belt driven fan is either grossly inefficient, does not draw more than 2/3 horsepower, or delivers gross, unuseable overcapacity. I know that cooling system engineers at a number of automobile companies have done extensive computer modeling and wind-tunnel testing to determine the optimum blade shape and number of blades for automotive fans. I can't assume these engineers are totally incompetent, and so, I must conclude that the belt-driven fans draw only a fraction of a horsepower, not 5-17 as some claim. I also must conclude that switching to an E-fan will have a negligable influence on gas mileage. If I wrong, why am I wrong? Does anyone know with certainty how much power a belt-driven clutch-controlled fan on a 4.6L or 5.4L motor requires during maximum cooling and minimum cooling?

 

Good observations IMO. Most people I've seen do before-and-after tests from stock clutch fan to electric fan say they picked up a couple to few hundredths. This would put the HP gain much closer to 5, than 17.

 

madenterprise.com has a nice setup.