So i was thinking for awhile about utilizing an aftermarket radiator fan mounted above the SC ( of coarse ) to pull more air in ( when driving and in traffic when your stop n go and theres alot of heat build up "heat soak" ) and i never seen a post for this ( or maybe im blind and didnt see any ).

Does anyone know how many CFM's we pull into the scoop and at what speeds?

How much room is there from the hood to the top of the IC?

Would it be better to have a thermostat to turn it on or a switch?

And if this is even worth doing?

I think for being i can do this for around a hundred bucks, it might be worth trying if nobody has done it yet.

 

Given that the hood butts up to the intercooler (or the scoop would be far less effective) I can't see that there'd be room for a fan.

Speed (aka airflow) is your friend.

 

I have a 600cfm rated radiator fan running above the intercooler, and while it probably only delivers half that in the restricted space, it does keep the intercooler cool to the touch even after prolonged idling or boost. Even with the GIAC it is obvious the car runs much better when the intercooler is not too hot to touch.

It is wired to the seat heater fuse to always run when the car is on. There is approximately 2 1/8" of static clearance if you remove the plastic scoop liner, but this drops when you pop the clutch and the engine rotates backward, lifting the intercooler. Limiting engine travel is thus recommended. The intercooler is also not centered under the middle of the hood that is the highest part, but that is where the fan has to go. Looking into the scoop shows the top of the spinning fan blades, so it is no place for curious fingers. Without the scoop liner there is no place to install a bug shield to guard against fingers.

The biggest trick is making a proper shroud to fit the round fan above the rectangular hole. It has to seal perfectly to keep air flowing down over the engine at all times, and also not limit airflow through the scoop at speed. After making various plastic and steel prototypes, I am now working on the final aluminum shroud which will allow airflow through all of the core.

 

Good sh*t..........I thought this would work but i just never got around to trying it out.....

Any pix? And what kinda fan did you use?

 

I suspect that if you did instrumented tests, you'd find that your fan improves performance of the intercooler at very low speeds (when you are not at WOT anyway) but that it makes performance worse once you are rolling (when you actually need that intercooler efficiency) since your fan acts as an impediment to airflow.

 

But now that falls back on....How many CFM's run through the scoop at different speeds. i think it wouldnt matter if your running the fan all the time so there is no way to "block" air flow being its pulling it in for you as long as its more air than normal.

 

Hence the need for instrumented tests. Easy to do, $50 in supplies.

 

I know your up for that Andy.....ITs allll you.

 

Yes, this is likely true because the hub of the pancake motor takes a lot of room and gets in the way of airflow. The solution for track use would be the addition of a larger intercooler, now that I have sufficient continuous airflow.

However most of my driving is not at high speed but stop-and-go, with sudden bursts of acceleration in between. This is exactly where heat soak from the intercooler (interheater?) makes the MCS respond sluggishly, and why keeping things cool makes for a much peppier daily driver. There is likely enough thermal inertia to run WOT for at least a minute before things get considerably worse than stock, and I'm not likely to continuously run WOT that long on the street very frequently.

My unscientific test is I ran WOT up a mountain pass with enough boost (19%) to light up the DSC light, then immediately pulled over to touch the intercooler. It wasn't too hot to touch, and that's cool enough for me. I've expended a lot of effort in perfecting a shroud to minimize flow restriction so plenty of air is getting through the core, and now I don't have to be at >40mph for long enough to cool down the core before the intercooler even starts working. The factory system is extremely well engineered, and funnels lots of air through when the car is moving fast, but worse than none while stopped, since heat rises.

I wouldn't try to passively cool a radiator, or an A/C condenser, or even a CPU heatsink. Imagine how big those would have to be to run fanless! I figured it would not take much continuous airflow to prevent heatsoak, and an earlier 200cfm prototype (which was only 15mm tall so no taller than the factory diverter!) confirmed that was indeed the case. This was a difficult mod and is not for everyone, but as I am just 1500 miles from the equator, it was worth it for me.

 

piiiiiiiiiiiiiix..........What type of fan did you use and where from?.....The one i found is from www.summitracing.com from DERALE Cooling Products

Part#DER-16508 8" 400CFM @ 2.32in thick for $67.88.
Part#DER-16509 9" 570CFM @ 2.39in thick for $69.88.
Part#DER-16510 10" 650CFM @ 2.6in thick for $69.88.

Or Flexalite
There single fan runs 1250CFMs with a 12" blade and only 2 1/4in thick for $106 and $130 with thermostat.

I have a good feeling a shroud might not be needed when im goin to mount this the same way the upper cowl is on. trust me....go turn on a house fan and feel what only less than 50 cubic feet per minute are.....now times that speed by ten and your not missing that intercooler plus the rest of ours motors to keep the underhood temps down. Dont get me wrong....the shroud is a good idea but i also felt that all that air flow could do more than drop temps in the IC. you know a 2fer

 

If idle/low speed heatsoak is the concern, one might want to seriously consider a water sprayer. I was going to (and still might) make use the horn buttons, to trigger a nozzle or two to spray distilled water for a period of 3-5 seconds. On some canyon runs, I've seen heat build-up (IATs) at lower speeds, like when exiting a series of tight turns. With respect to Andy's commentary, unlike a fan set-up, the impact on airflow should be very minimal...

Also, a larger hood scoop makes a very notable difference; more so than going from the stock IC to an uprated one (at least the one I tried). The stock one seems quite effective.

When feeling the IC, we expect it to be hotter on the left side vs the right (driver, outlet) side. However, also check the front to rear for any differences. The provisions for this on the stock unit seem very good. On the larger one that I have, there is no diverting of air to the lower or front portion of the IC. I noticed it being hotter than the rear that was getting crammed with the cooler ambient air. I see this as an opportunity to improve upon this, and I'm currently mocking something-up toward this end...

 

A water sprayer would run out in seconds if you used the headlight washer bottle for cars that dont have one or lose more trunk space with a big tank. The fan is more logical for the room it takes up ( none your gonna miss ) to having to keep refilling the bottle or hitting a button. I have a water sprayer and its ok for what it is but i like the fan idea and know it will be suffient and more affective at that.

 

I would agree with Tony here.
I'm not really understanding why one needs to have a fan on the IC when in stop and go traffic unless you are in the habit of racing the car next to you from one light to the other.
Numbers would be interesting, but I would bet that Tony and myself would run much cooler on unobstructed roads then someone with one of these fans.
I use the IC sprayer a good amount on the road and track and it last quite a long time. Your not spraying all the time as it's not the water that's cooling the IC down. It's the evaporation of it that cools the IC. (I'm sure I'm not telling most of you something you don't already know).
I also have the M7 scoop that I would highly recomend as a Mini S must for better performance. (Also use the Alta IC and have done work to clean up under it for better air flow, and have a seperate IC water tank)

I have used two types of fans on the IC while dynoing the car. It took quite a large attic type fan to work effectively, as the smaller one just could not keep up, and it was not all that small.

 

Anything that disrupts the airflow, or decreases the volume of ambient air over, and through the IC is detrimental.

I did data-logging runs on a 16 mile stretch of rural/canyon roads, replicating the best I could driver input (RPM, boost and speed), and temperature (multiple 68F & 98F runs), and found that volume of air, and how it's focused or directed makes a difference. From this, putting something in that path, I feel, is not prudent...

As onasled said, an IC sprayer, if used at the most needed or ideal times only, will last plenty long. With a 3 second delay off, I can trigger it with a quick push of my horn button and it/they will spray water for 3 seconds dowsing the IC, then turn-off at 3 seconds. Most of my lower speed twisties last about 3 seconds, thus my reason for wanting a 3 second delay off feature. By the time the 3 seconds is done, I have enough straight to up the speed for better ambient flow through the IC. One could choose 5 seconds also...

If a 3 second blast uses a cup of water (most likely less), that would be about 14 or so uses with the capacity of something as small as the Xenon tank. With a 2 gallon tank, this would be at least 32 times... On my canyon commute, I have about 6 spots where speeds are relatively low, and this could benefit me, when I want to push it...

I thought about an IC fan before, and even one below so it could help pull air through at low speeds. But, there is such limited space below, and if that's compromised, flow through at higher speeds is also...

It seems that the ideal set-up would be auto injection for when hammering it hard. It would be triggered with a combo of IAT reaching/surpassing a certain point, with either RPM or boost hitting/surpassing a certain point; for example- something like 160F IAT, at 5k+RPM or 11+ lbs boost...

And the IC sprayer to be utilized, probably manually, for just prior to hammering it, like at idle or relatively slower speeds, to take the edge off...

 

if all the air could get through the stock hood scoop un-restricted, at 60mph you would be passing around 4000 cfm

Note: correction made to alky-induced arithmetic error
(60m/h=1m/min=5,200ft/min) x .6 sq-ft= 4200 cu-ft/min

 

Stock scoop?

 

onasled, jlm edited his post above, and also addressed your question...

So, what was the cfm of the attic fan used?

 

after all the reading, i started thinking, maybe it is better just to cut off the hood like the EVOs. leave it exposed.

from some point, it might do better then have the scoop. at least it is better to let the heat out of the car.

about the air coming in.... i dont think if will do much different with of without the scoop since the IC is not completely flat on top of the engine. it still have a slightly degree facing towards the front coming air.

Maybe someone can try it one day with no hood at all since it is the closest thing without actually cut the hood. i think some one who is going to install a CF hood could try this out one day before the CF go on there.

Just some thoughts

 

venting a carbon hood is in the worx.....

 

I guess my theory was just shot down like JFKs plane.

 

I came to at about 6am and measured the stock opening to be about 1" x 13", that is about .1 sq ft, not .6, so the cfm at 60mph then is about 520.

 

FYI, the hottest I've ever seen my intercooler outlet on the road is about 90*C (about 190*F), which was accomplished by idling, stopped in traffic on rt-309 in 90*F+ weather. As soon as I started moving AT ALL, temps dropped considerably. Despite the insane IAT's the car still behaved fine and accelerated smoothly once traffic had cleared. IAT's dropped to 45*C very quickly.

 

I wanted to say something but im not a math genius. I thought that was waaaay to many CFMs ....

 

One more thing. The calculation of area x speed = volume only works if all of the air is sent through the scoop. We all know this is not the case. Much of the air goes right over the scoop because it's flat and the air won't bend that much, in such quantities. The initial 'bump' that the air sees at the front bumper deflects the majority straight over the scoop, not into it. The M7 scoop is much more effective, because it does not essentially depend on passive induction- it traps the air after it's been deflected by the front fascia of the car. It brings the volume of trapped air closer to the maximum volume passing by.

 

So in other words....it sounds like this will work then.