Yeah.. what he said. Bueller?

 

Actually, I have heard rumors at work that we actually designed and manufactured these fans back in the day. I know that the Fan and Fan Clutch for the FC is from my company.

I agree with what some people have said.

Number of blades does not necessarily increase airflow.

Without changing the blade shape, you could potentially add too many blades and actually reduce the airflow. More than likely any fan that is from an OEM does not have this problem.

The blade shape, diameter, and tip clearance all factor into the fan efficiency (airflow -vs- power draw).

If the motor is more efficient (output fan torque -vs- current draw) this will help regardless of your fan shape, and you will have better airflow.

Increase in airflow will not necessarily increase cooling. Cooling efficiency is also dependant on the Radiator. If the Radiator is already at maximum cooling capacity, moving more air across it is not going to help.
The solution to this would be to get a radiator with a larger cooling capacity.

If anyone is interested, I can test a fans airflow performance with an actual "Airflow Tester" per ASTM specifications.
Sorry, I don't have the money right now to buy all sorts of different fans to compare.

In addition, I could test the performance of both the Fan and the Fan Clutch from an FC, if someone was so inclined to ship one to me which was in good working order.

Bryon

 

In addition,

When you guys are throwing around cfm values, were these measured per some ASTM (American Standard Test Method)?
They were probably not measured with the entire "system". I.e. the radiator, condensor, and something to represent the engine... all of which change the flow pattern and resistance.
Thus, the actual fan efficiency will change, and not necessarily the same amount for every fan. Certain fans "respond" better than others. This is mostly based on blade design.

I guess since the blade design of most electic motor fans are the same though, this won't really matter.

 

Hey Byron, that brings up a question? If you reduce the backside resistance to airflow for the fan, does most likely help or hinder? What I'm getting at: I moved my battery out of the engine compartment, and I'm wondering if the loss of this fairly large restriction to backside airflow from the fan below will tend to hurt, or help? Or is it just too dependent on the specific fan blade and fan motor combination?

 

Well, I have NOT had a chance to throw the stock fans back on yet... but I'll tell this:

If I start the car cold, and turn on the fans the car won't climb over 83C regardless of driving. I haven't gone bonkers yet, but spirited driving won't raise temps over 83.

If I start the car cold and let it warm up and drive it till the fans come on automatically (87) the temps drop nearly immediately to 84-85.

I have NO vented hood, and a huge heat producing single with a FMIC. If I leave the fans on after shutdown, the radiator is cool to the touch after ~2 minutes. They really move some air. I can let it idle with the hood closed all day and not worry about overheating.

I've managed to get the temps to 89 (unplugged fans) and as soon as I turned them on the temps were down to 84-85 in no time.

If I get the chance I'll stick the stockers back in and see what kind of difference there is. Can't promise when though... But I'll see what I can do.

I also do reallize that the thermostat doesn't even open until 87.. this thing runs very cool.. I have not yet seen over 89C. I know both the PFC and the Gauge aren't wrong.. The temp here hasn't really been hot, but ~75-78F.

I'm tuning for more boost this weekend so we'll see if I can get the temps up anymore..

 

From my altzheimer memory,
cooling while driving hard is mostly from ram air, and the post-US 95- Japan models improved that by revising airflow path/baffling/intake so the ?intercooler? was no longer cross-flowing to the air intake? or some such thing.

Engine shutdown heat soak is reputed to cook some of the plastic by the rats' nest. Recommended stab at that is the delayed ignition shutdown timers that run the engine at idle to cool down for a while.

I would like to see a simple mod of a blower to keep airflow across the top of the engine after shutdown until achieving either: temp drop/ time elapse/ or voltage drop. Anybody done that?

Fan blade change is interesting, but does not seem like it is the choke point for most problems.

 

It might MOSTLY be from ran air, however if your going 85mph and cut the fans on high it will drop the coolant temp.....that leads me to believe that even at high speeds the fans are still benificial.

Matter of fact this is how people change thier coolant temps with the PFC, they just set the fans to come on at a lower temp and that temp is then kept pretty much solid with just the fans. Thats pretty much positive proof that the fans are still capable of cooling down the coolant even at 85+ mph and its not all ram air cooled.

STEPHEN

 

Yes, reducing back-side resistance will increase airflow across the radiator. Battery, etc are restrictions that block the air from flowing.
Think of it this way - Totally enclose your engine compartment and then run the fans. If they were moving air across the radiator, then the engine compartment pressure would be going up, since no air is escaping. So back-pressure is like the ability of the air to continue to flow (escape)

Ducting -
Also, like it was mentioned, the ducting is crucial. It forces the air to flow across (through) the radiator. The airflow will try to find the "path of least resistance" so you have to force it with ducting.

Ram-Air
The ram-air is going to be the majority of the cooling, but from my own personal experience and experience from others I'm sure, the fans ARE sometimes needed even during high-way speeds. (My drivers-side motor went out, and my high-way temps went up by 5C until I got it replaced. This was with casual driving.)

Also SPOautos - I got your pm.

 

Fan mod - fan mod - fan mod - fan mod - fan mod

Keeps the fans running for 10 minutes after shut-down.

Sure, it cools the coolant in the radiator, but that's friggin' pointless since the waterpump isn't running.
More importantly it blows air onto the engine, and also the rest of the engine compartment.
If you've done the fan mod and you feel hot air coming from under the car or wheel wells, that's a really good thing
(I haven't done the fan mod yet... I'm such a lazy idiot)

 

with stock fans and fanmod my temps never go over 180. if i do let it go over 200 with fans off and then i turn on the fans, it goes down to 180 in a matter of moments. after i park i use the turbo timer to keep the coolant running while the fans run for a minute.

is there really a need to upgrade the fans?

 

Is anyone ever stuck in traffic?

I always run about 89C-95C while driving normal any speed really. Anyway I was stuck in traffice several times and seeing anything over 100C gets me worried. I have even been to 107C, anyway the fans are running as hard as they can, but temps just dont drop. When I put my fans (99specs) in I will see what happens to the car in traffic. Im very curious if they do in fact work. I have no fan mods nor have I used DATALOGIT.

I want these fans MOSTLY for traffic, since you cant even turn off your car or anything in these situations, you can only just watch it overheat.. Anyway.... SOON>>>>

Incase no one knows, I was in a pretty bad car accident hit from behind at approx 35-40mph, yeah it hurt, but I dont know whats up with my FD yet till monday or tuesday, so I dont know when and or IF i will ever get my FD back or get a newer one and then i wont need the fans hehe...