Are electric fans worth it?
- Thread starter DyslexicSquirrel
- Start date
figgie said:
Exactly, I'm not sure where FAL gets their numbers at but the SPAL dual fans pull WAY more air. It's not even close. FAL is also not rated for 100% duty cycle. They will fail prematurely if hooked up to ignition without a thermostatic switch or fan controller. I have a FAL dual fan in my garage with a burned out motor if you don't believe me. The dual 12" SPAL fan pulls enough air to be used on rear mounted radiators in off-road racing trucks with 750hp na engines.
It does not matter because electric fans are a subject where people just don't take good advice. We'll let them lean it the hard way, right IJ? :icon_wink
figgie said:
This is correct. most likely that number is at 0 inchs H20 presure a very Ideal state of being. with more realistic .3 to .4 inches of H20 presure flow would more likely be around 1800-1500 cfm
bigaaron said:
i think you got factory fart fan there
you chould do what i did and changed the magnets and bush in the fan
i sup on my cooling fan funny eh push way more air then t did befor and it was rated at 2000 some thing
NashMan said:
Thanks, but I think I would just spend an extra $40 and get the SPAL fan.
Actually if I was really worried about cooling I would just buy a new Toyota fan clutch.
dude i had this great idea stuff needed frezzer and some duck tape
man i got to stop waitching the red green show lol
man i got to stop waitching the red green show lol
This in incorrect, so the rest of the point is too. A shroud is so you pull air over the entire surface area of the radiator. Distance has nothing to do with it. If you haven't noticed, FWD factory cars also use a shroud.
That simply isn't true.
You can put a fanclutch right up to the radiator also without it hitting the radiator.
Nick M said:
Have you seen the amount engines move in an engine bay? I have and I have seen the carnage done to radiators by fans mounted to close to the radiator.
I know the shroud does give better flow to any type of fan. The shroud allows the fan to affect a greater disk of air effectively increasing the diameter of the fan. However the efficiency of a shrouded fan is very dependent on the edge clearance.
This article explains the reason in engineering terms
http://divisions.asme.org/fed/newsletter/TechBriefFoss.pdf
“THE AERODYNAMIC SHROUD (AN MSU INVENTION)
The aerodynamic shroud, shown schematically in Fig. 10 and described by Foss (1998) and Foss and Morris (1999), provides two distinct benefits for the axial fans considered in this communication. An engine driven fan must be configured with a large tip clearance given the relatively large (25mm) motion between the chassis mounted shroud and the engine mounted fan. A concomitant result of this condition is the presence of large .tip region losses. or flows from the pressure to the suction side of the blade in the tip region. A ventilation fan will typically operate with a small tip clearance,”
An electric fan will always have closer tolerances than a fan mounted separately from its shroud. Now a shrouded fan can be mounted further away from a radiator and not loose any performance but only if you can keep tip tolerences tight which is not possible with a fan mounted on a engine mounted on rubber blocks
give me some credit I did pass fluid dynamics the first go around:biglaugh: unlike calculus C :cry:
The only time I have seen a fan ruin a radiator was when the water pump came uncunted. That has nothing to do with the topic.That is like driving a RHD car in the US becuase somebody might crash into you on the LH side and hurt you. I have seen my fair share of running engines.ToyoHabu said:
That is true but the OEM shroud has little to do with CFM, and everything to do with surface area. With out a shroud, you only pull air directly where the fan is. If it was just CFM, it would be much cheaper to apply more current to the electric motor, or a more viscous fluid in the clutch. It wouldn't require money on R&D.
I don't think shrouds were invented in 1998.:nono: Perhaps they invented a new shape of shroud?
Electric fans come with a shroud too. Maybe not some aftermarket units that are saving money and weight, but OEMs do for a reason.
Keep after it. $$$ is waiting.
That isn't to say shaping the shroud like a modified air horn won't increase CFM, because it will. But that isn't why there is a shroud.
Done finished and making plenty of $$$ :naughty:Nick M said:
I have done experiments on cooling effects of shroud geometry on fan efficiency and tip clearance is king. Indeed the shroud in the automotive application ensures that the air that is induced to flow flows through the Radiator. The tip clearance still has a major role to play. Using smoke generators to see the flow helps a lot. What happens is that air on the back side of fan can be drawn into the front without traveling through the rad. see crude image View attachment bypased air.bmp the problem faced by engineers(that’s me) is that getting tolerances tight cost money. Various issues in the design of a cooling system. Plastic is not thermally stable (must make clearance to accommodate this) Engine is not rigidly mounted ( must make clearance to accommodate this) so fan is not as efficient at move air as it could theoretically be.