Hi All

I finished making the comparison list on the Gbobal Vicinityl How To Site.

You may just learn something. Here it is.

If you have information about the fan you are using, you can put it up on the same page.

http://howto.globalvicinity.com/gv_w...=132&co=1&vi=1

 

Uh, thats great and everything, but I'll pose the same question to you that I've posed to every other joe that says the stock clutch fan flows more air then a 2800CFM Flex-a-lite:

How many CFM will the stock clutch fan pull when fully engaged? And, is that number greater then 2800CFM?

No one's been able to answer that accurately without the "Well it just flows more" statement.

The only advantage I see to using the stock clutch fan is that the shroud fully covers the face of the radiator where as a black magic or any other fan covers the center of the radiator.

I replaced the clutch fan with the e-fan because it failed not necessarily because I thought it would make a great performance mod. I like the idea that I can have it wired to constant 12v so it dissipates heatsoak after the car is off and thermostatically controlled. Maybe its just a warm and fuzzy for me, or maybe it really helps prevent the car from cooking itself after the water stops moving when you shut the car off. Theres no way to tell other then the lower temperatures after the car being off for 10-15 mins.

 

It will at higher RPM. When the clutch fan is engauged fully, it spins at 80% of the engine rpm. So if the engine rpm is 3000rpm the fan is spinning at 2400 rpm which I believe is around 1500cfm. A lot of times the fan is spinning slower then that. At idle the fan would be around 600CFM.

I have changed everything on that page since last time.

Yes at higher RPMs. Not at lower Rpms such as idle or low rpm cruising.

Steve has worked on a page on GlobalVicinity.com that tell you about the clutch fan. Till I ran into money troubles which I hope to come out of shortly, I was going to buy an airflow meter to measure actual airflows of the clutch fan and different e-fans.

http://howto.globalvicinity.com/gv_w...=191&co=1&vi=1

Yes and you see how the shroud is designed? It allows the air flow through the heat exchangers to not abruptly stop or slow down like it would with a full rectangle shroud with a 17" hole in the middle of it. This could cause resistance in the airflow and could cause cooling issues. The best setup would be a shround and fan setup that only covers 80% of the radiators surface with the shround covering about 20%. This will allow the airflow through the radiator to keep flowing at high speeds so the e-fan does not have to come on.

http://howto.globalvicinity.com/gv_w...=149&co=1&vi=1

Bad idea. Running the fan only off a thermostat while the car is off will drain your battery if the outside temps are hot enough. The fan may never shut off. I have personal experience in this years ago.

Wiring an electric fan
http://howto.globalvicinity.com/gv_w...=148&co=1&vi=1

Running the fan will only cool the radiator and will only slightly drop the temps on the out side of the motor. Its not going to cool the entire engine. Letting an engine sit for 10-15 minutes without a fan will also drop the temps. The engine can't produce MORE heat when its off then it does when its running. So with that said, your engine will not COOK.

 

Thats not entirely true. In fact If I had a video camera I could record proof for you on my PFC that shows temps rising after the car is shut off. I'm not talking about the difference of a few degrees here, I'm talking the difference between 80C and 90C. It's called heat soak and to say it doesn't happen is outright absurd. It's not producing more heat, the cooling system has stopped working, therefore heat that already exists is now allowed to radiate unchecked.

The thermostat is adjustable for climate changes. I also have a deep cycle yellow top. I've been running this non-ignition switched setup for 2.5 years with no problems.

Agreed on the fan shroud idea, I'd like to see that implemented.

 

Personally, I'm a beliver that a clutch fan is not ideal most vehicles.

The variable speed of the engine controls the CFM instead of a fan controller, using a thermostat to measure what speed it should actually be at.

I used my MegaSquirt ECU on my S5 'Vert, to control a set of stock twin MR2 fans. Unlike the clutch fan, it only turned on when nessisary (thus, using less total power, dispite the conversion lossess from mechanical power to elecrical power and back again).

The MR2 fans were quiet, and in that they covered almost the entire radiator, they were very effective. Turning them on for about 15 seconds would cause the temp to plummet like a rock, even in 100 degree heat while the car was sitting still in traffic.

Removing the stock clutch fan also eliminates the need for a twin alternator pully (as the belts will no longer slip on the waterpump pully).

Also, heat soak is a definite reality. A decent controller and a decent fan can bring temps down to appropriate levels in a matter of less then a minute. Even at 120 degrees ambient air it should not take long to bring water temps below 179 degrees.

You'd have to use a very crappy fan or fan controller to kill your battery from it being left on.

 

I would not say that 90c is heat soaked by far. That is only 192*F and is close to normal operating temps which range from 186-192 . So thinking 90c is heat soaked is absurd. Like I said, the engine can not produce high temps while its off.

I guess the yellow top is the reason its worked for you. Any other battery and you would not be able to start the car. This happend to me on many occasions and its also common sence.

This also is more leaning toward those of your with fans sucking up over 14amps worth of current.

 

I agree about the clutch fan. Although its able to control its rpm by temp as well to a maximum of 80% of shaft rpm. On stock vehicals that are not being raced around all the time this would be fine.

I want to look into fan controls from SPAL and I think there is another brand out there as well at summitracing.com. I don't see a reason why my fan should come on full blast when the temps are not close to the red zone, especially during idle when temps are much easier to lower.

I have a 16" ebay fan with no shroud in the center of the rad and it drops temps like a rock. Personally, I don't think a full shroud is needed by any means unless you have are racing in hot weather or somthing like that.

I really hope you are not trying to bring the temps below 179 since normal operating temps are around 186-192. Below that is overcooling the motor and will decrease performance.

Heak soak is only an issue while driving. Its obveously noticable. You will not cook your motor by turning it off without a fan constantly running.

 

I reread the page and at 3250 engine rpm the stock fan would pull around 2160 CFM at peak pressure. 2916 CFM at Zero static pressure. At 2000 rpm, fan at 1600rpm (80%) the fan at peak pressure would be around 1350 CFM.

The Black magic 150 fan says it pulls 2800 at 0 static pressure. This means without it on the radiator or any other surface. At peak pressure it would be around 1760 CFM.

 

Thermostat controls engine temp itself, not the fan.

But OK, lets examine what occurs when an engine runs colder.

It will (VERY slightly) increase performance. (The difference between 179 and 186), difference becomes more pronounced as temp drops, eventually to the point of diminishing returns.

Decrease fuel economy tho.

After a certain point, wear will begin to increase slightly and fuel economy will become abysmal.

It should also be noted that colder engines must run richer, and with more advanced timing.

 

How can you say this? Yes the thermostat is used to keep engine temps around the norm but above that the thermostat is usless. You need a fan to control the engine temps after the engine reaches norm operating temps.
I can't go into scientific explanations of why performance could decrease when the engine runs below normal operating temps but performance does atleast on both of my engines have decreased when the temps are lower then the normal operating temps.

The only portion of the RPM band I find has drastically increased performance is low end up to about 3000rpm. After that, engine hits a brick wall. Its just common practice to have the engine at normal operating temps. If your thermostat is rated to start opening at 182 or 186 which is where OEM T-stats open. Then trying to cool your motor down to 179 below will be very hard.

Where do you have your temp sender located?

There are many reasons why the engine should be at Normal Operating temps before pushing the motor. I just hope someone with more know how can shed some light on this.

 

You claimed that the fan alone would cause over cooling. I pointed out that this was not possible because the thermostat would simply shut if the fan cooled too much. Then you replied with the above straw man argument. I said nothing about the hot side as you reference here, I was referring to the cold side.

I can go into scientific explanations about why performance does increase at lower engine temperatures (to a point) but I'll only go into that if you want me to.

But just some quick facts:

1) Colder running engines require less octane fuel. (Every ten degrees is one less octane point needed)
2) Colder running engines are more resistant to detonation.
3) (Or twenty degrees cooler can equal one degree of extra boost) (Just a rule of thumb, not always the case, just as with rule #1)
4) All other things being equal, a colder engine can take a richer AFR and make more power from it.
5) A colder engine should run more timing advance effectively (because of the slower burn)

Your ECU sounds like it's not tuned right if it hits a brick wall when engine temps are at 179. You're _probably_ running lean.

Not really. The fan cools it down so much that by the time the T-stat closes, the engine's already at 179. Then when the t-stat shuts, the engine slowly heats back up those few degrees, t-stat opens a little, and temps balance out.


On the one I was referring to (the convertible) I have it in the stock location, right behind the thermostat.

As the tuner, we are the ones who decide what "Normal Operating temps" are.

We can opt lower (down to around 160) for power, or higher (up to I _think_ around 205) for fuel economy. Mazda picked their range based on the best compromise of fuel economy, power, and reliability.


I'm not trying to be confrontational, I'm just trying to inform.

 

PS: Just as another informative note; whenever I get to tune a cooling system for a street car, I shoot for 175 degrees to 180.

 

Understood, same thing over here to. Im not trying to argue. Just trying to understand each other.

I thought you were refering to the hot side not the cold side, sorry . I have my temp sensor for my greddy gauge on the back of the water pump housing. So I read the hot side of the engine.

I know some owners use 160 degree t-stats and try to run the engine as cold as possible with an electric fan. This is what I was refering too. I was not very clear at all though. Considering I was talking about the hot side and you the cold side.

What I have noticed anytime I run without a T-stat, which I don't do normally and don't like to do it. The engine temps on the hot side would stay around 180 +/- 10 degrees. So when you say the t-stat controls the temps, yes and no because the engine temp will only go down so far untill the e-fan setup starts to struggle keeping up with the heat generated by the engine. Now if our water pumps where high output water pumps then I could see how you could get the engine temps down a lot more.

This is what I have observed on many situations. Whether it does it with other owners, im not to sure.

You are refering to the cold side correct? If so then I absolutly agree. Like I said earlier I jump the gun and thought you were talking about the hot side getting down that far which would make the cold side near 165 or just above.

Understood. The rest of what you posted is basically me not knowing you were refering to the cold side of the motor.

With that said I don't have any disgreements. Unless you surprise me with something

 

to add to your list..

the Fiero GT fan has straight blades. I'll measure the size of the shroud and the fan next time I go home to work on it.

-Myk

 

^ That will be FANTASTIC!

You can post it on the table yourself. Just register at globalvincity.com.

 

How much CFM will the Taurus e-fan flow?

 

I have a brand new Clutch fan and Koyo Aluminum Radiator in my stock S4 NA.

A few thoughts:

1) During track events with the AC on in very intense Florida heat my temperature climbs to half guage (and a bit above sometimes) easily
2) I have a stock exhaust system (very quiet 7) and I can tell you the stock clutch fan is LOUD

I'm not comfortable with the temperature increases (*very* high mileage engine, as you can see from sig)