Douglass

Hey i have a non turbo 89 gtu...and im wondering if i could get a ford taurs fan to fit my car...i hear there pretty small fans....i want one for my car....what else would i need besides the fan...????

NZConvertible

Read this. All of it.

http://www.aaroncake.net/RX-7/efanmyth.htm

Kenteth

sums it up pretty well eh? I just reinstalled my clutchfan after the 5spd install. I always remembered how much that thing really blew, and no matter what fan i had on the radiator (even if it was keeping the car cool) didn't blow nearly as much.

With the old clutch fan on, and a new radiator shroud, I can sit behind the car and feel hot *wind* at idle... Love it. good way to heat the garage duringwinter too,... (lest the exhaust)

OverDriven

That article is meant to be helpful, but there is alot of contradiction and mis-information in it. First, it states that the electric fan may over-cool the engine. It then goes on to say "They provide inferior cooling to the stock fan" at the end. The biggest thing that bugs me is this:

Electric fans draw quite a lot of current. Most pull surges of 35A or more to start up, then run at 8A-10A. This puts extra load on the alternator. Ever pedaled a bicycle with a generator powered light? If so, then you will know that as the electrical load on a generator/alternator increases, the generator/alternator becomes harder to turn. Suddenly, all that "free" HP you just freed up is once again being used. This time, though, it is being used to turn the alternator.

That paragraph is absolutely untrue. The alternator is no harder to turn under load than it is with no load. I have no idea where this info came from, but it isn't accurate. This post isn't meant to put down aaron, but just to state that you shouldn't believe everything you read.

-Joe

Crionics

The fans from the 3.8 L Taurus' fit perfectly over the stock radiator, and many of my friends run that.

Crionics

Also, whoever did that website should seriously consider changing the colors. That is absolutely horendous and hard to read.

91_fc

in the reading it said that the fan only begins to work when the car is not moving going less than 20 mph. he also said you only gain a .5-1hp w/ the electric fan conversion. this means in motion (over 20mph) the fan (either an e fan or not) will not spin because wind is already passing through. wouldn't this mean that you gain your hp back at this time? isnt the hp only lost at times when you are under 20mph, a rather insignificant time?

91_fc

please correct me if im wrong.

91_fc

somebody answer meeeeeee!!!!!!!!!!!!!!!!

91_fc

somebody answer meeeeeee!!!!!!!!!!!!!!!!

91_fc

somebody answer meeeeeeee!!!!!!!!!!!!!!!!!!!!!!

91_fc

somebody answer meeeeeeee!!!!!!!!!!!!!!!!!!!!!!

91_fc

somebody answer meeeeeeeeeee!!!!!!!!!!!!!!!

ForsakenRX7

I put an electric fan on cause I dont trust the stock fan. Noone can tell you the CFM rating. And I havent seen a lick of problems with my electric. I can turn the car off, leave the key in accesory and have the fan on to help cool the motor. Horsepower gains if any are going to be so minimal that you couldnt tell unless you had a dyno. But I think its a modification worth doing. In my opinion if clutch fans are so good then why do new cars come with electric fans?

RRTEC

iTrader: (13)

^^^ditto^^^ ever stood there and listened to the drag the stock fan puts on the motor...?

OverDriven

Well...leaving the fan on after you turn the car off won't really help cool it much because the water pump is no longer circulating coolant through the engine.

-Joe

scathcart

Speaking of myths...

"As the engine heats up, so does the clutch as hot air from the rad flows over it. The fluid thickens up, engaging the clutch and turning the fan at engine speed up to about 2000 RPM."
What fluid thickens as it gets hotter? This would indicate that its molecules are moving slower, which disobey the laws of kinetic energy.

"The '86-'88 alternator is rated at 70A, and the 89+ unit is rated at 90A."
The S5 alt is rated at 80 amps, not 90 amps.

"The electric fan introduces many more failure points: fuse, all wiring connections, physical failure of the fan, failure of the motor, failure of the thermostat. "
1. Fuses don't just fail. If a fuse pops, there is too much current being drawn through the fuse, either via a short, poor installation, or too small of a fuse.
2. Physical failure of the fan? Gimme a break. Are blades going to come shooting off? is it going to rattle loose and become unbolted?
3. Failure of the thermostat? Umm, electric fans should retain use of the thermostat. No added failure modes here.
4. Wiring? Properly routed and installed, this is not a reasonable failure mode.

The only failure modes of an electric fan are the motor failing and the thermal switch failing (which is very common with some brands).

If we are going to mention all of the failure modes for the electric fan, let's not be biased here. The stock e-fan, along the same lines, can:
- belt slippage/ belt breakage. Very common when the air pump is not installed.
- Thermal clutch fail (common)
- physical failure (yeah right, but if it get's listed for an e-fan, fair is fair)
- Improper installation (again, yeah right, but if it get's listed for an e-fan)
- thermostat (listed for e-fan...)

As well, many new cars are using e-fans because...
1. They are FWD and the crankshaft sits perpendicular to the radiator.
2. Space constrictions do not all the fitting of a large standard fan.

Rob500

"What fluid thickens as it gets hotter?"

20-50w Oil.

Rob

Kenteth

1) Aaroncake probably has an EE and the various certs that go with it. the highschooler's that don't know what an EE is... need not critisize him here.

2) Viscous type clutch fans use a fluid that THICKENS as it gets hotter. Any ME will be able to list of LONG list of synthetic and natural liquids that hold this property true. Again... most highschooler's won't know what an ME is, or know that there are fluids that thicken as they get hotter. Thermalfluid dynamics, k thanks.

That said, I thought RX7s had a thermalstatic fan anyway? Thermalstatic uses a spring instead of fluid, and is more on/off, than slip/noslip.




EDIT: Heres what I was looking for: http://www.haydenauto.com/f_clutch.html

scathcart

Are you kidding me? Even the name 20W50 tells you it gets thinner as it heats up. Why you do you think we do oil changes when the car is hot?

scathcart

Heading into fourth year mechanical Engineering, FYI.

drago86

[QUOTE]Originally posted by scathcart
[B]Speaking of myths...

"As the engine heats up, so does the clutch as hot air from the rad flows over it. The fluid thickens up, engaging the clutch and turning the fan at engine speed up to about 2000 RPM."
What fluid thickens as it gets hotter? This would indicate that its molecules are moving slower, which disobey the laws of kinetic energy."


Well, despite what many people think, the fluid doesnt thicken as it heats up, even howstuffworks.com gets this wrong, equating it to a viscous LSD (as many people tend to do as well), which works on a differnt pricipal, the shearing action betweent he plates of each wheel which "streches out" polymers suspended in the fluid causing it to thicken. Note that this does not involve heat to thicken the fluid. Viscous LSD fluids however are resistant to thinning out as they heat up, much like multi grade oil, however they do not thicken with heat.

A Viscous clutch uses a thermaly controled valve and a thick fluid to control its speed, the hotter it gets the more the valve either opens or closes (depending on design) to let less fluid bypass the clutch mechanism.

http://yarchive.net/car/fan_clutch.html

http://www.designnews.com/index.asp?...CA117022&cfd=1

"An early approach to reducing the load on diesel engine fans was the application of a viscous fan drive, a technology in use on many automobiles today. Essentially a fluid-coupled device that operates much like a variable torque converter, it consists of a hydraulic turbine with silicone fluid that operates through centrifugal force. A valve, which is controlled by a bi-metallic element that senses the temperature of air passing through the radiator, controls the amount of fluid-coupling slippage. The less slip, the more efficient the clutch, and the higher the fan speed. "

http://www.machinedesign.com/ASP/str...tedArticle.asp

drago86

2nd year ME :-) ( i know,.. thats not much beter than any other science /math major at this point...) But Scathcart is right and you guys are wrong.


20w50 does not mean i thickes with heat, it means it is resitant to thinning

20 means at pour temp it has the viscosity of a 20 weight oil: W mean the oil is rated at the boiling temperature of water: 50 means at the boiling temp of water its viscosity is equivelent to that of a straight 50 weight oil at 100 C

note that this is still thinner then the 20 weight rating at pour temp!

Kenteth

In that case you've got a few semesters on me... So you know how it is I suppose -- I took a look at Aaron's site after I posted. I'm not so sure he does have an EE degree now?

NZConvertible

The info is correct, you've just misunderstood it. He's talking about two separate issues. If you have a fan that is of sufficient capacity to cool the engine, and you run it constantly instead of thermostatically, you can overcool the engine. However if the fan is not of sufficient capacity, it's cooling will be inferior to the stock fan. Read more carefully before you criticise.
C'mon man, this is basic physics. An alternator converts mechanical work into electrical work. The more work you put in, the more work you get out. The more current an alternator generates, the more power is draws from the engine.

Who the hell cares? It doesn't matter what its airflow rating is, because we know that it's enough. Overwhelming experience shows that the stock fan with a healthy thermoclutch will have zero trouble keeping the engine cool. The no reason to trust it any less than an electric fan; in fact an electric fan introduces more points of failure. Plenty of people have engines overheat because of failed e-fans (usually caused by substandard parts and/or installation).
You need to take a closer look at new cars. FWD cars have e-fans for obvious reasons, but most new cars with longitudinal engines still use a thermoclutch main fan combined with auxiliary e-fans, just like the FC. This is simply because they work so well. Exceptions are cars with angled radiators under low noses (like the FD) where e-fans are simply more practical from an installation point of view.

It's pretty obvious he means the motor, not the impeller. I know they fail, because the one in my stock e-fan just did...
Again, it's pretty obvious he's referring to the thermoswitch, which can be correctly referred to as a thermostat. And we all know cheap ones are far from reliable.

C'mon Sean, you're just splitting hairs here. You know what Aaron's getting at. Nowhere does he say e-fans are crap, just that there are a lot of people who believe a lot of crap about them (see above). A properly selected and installed e-fan can work fine, but the actual gains in performance and cooling are practically zero.