Wheel/brake cooling fans: Crazy?

Slowly getting the front suspension back together. Trying out some stuff to hopefully get rid of an understeer issue on tight corners by changing the caster and camber curves during cornering (wish me luck).
There's an additional item I'd like to try for amusement once I get some material. While I don't seem to have a noticeable brake cooling problem I'd still like to get a bit more airflow to the brake rotors. I've been just diverting some of the undercar air up to the rotors as the usual air hose ductwork doesn't package well with the C4 front-steer rack and suspension under the car. I keep entertaining a fan disc sandwiched between the wheel and the hub/adapter (a poor man's version of the fans on some old road racing Corvettes and 935 Porsches). A 15" OD fan will fit inside my C5 track wheels. I'm wondering if 1/8-3/16" sheet aluminum (cut to a 15" diameter with angled vanes in the outer 4" of the disc) would work (with narrowed adapters to preserve the trackwidth). I'm curious if this would pump air out of the wheel well, cooling the brakes, and as a side effect possibly reduce the amount of air that goes under the floor of the car causing lift and drag. If I did the math correctly the front wheel (and the fan) would turn a max of about 1850 RPM at 140 mph.

So, is this a crazy idea? I welcome any constructive comments.

I think you are talking about pulling air from the back of the rotor and out through the wheel, right? Controlling the flowpath so that air is passing over the surface of the rotor might be a challenge and complicated because the rotor is turning with the wheel.

A long time ago I saw someone that was spraying water (aerosol) into a brake duct actuated by the brake pedal. Pretty clever and probably effective.

BBShark said:

I think you are talking about pulling air from the back of the rotor and out through the wheel, right? Controlling the flowpath so that air is passing over the surface of the rotor might be a challenge and complicated because the rotor is turning with the wheel.

A long time ago I saw someone that was spraying water (aerosol) into a brake duct actuated by the brake pedal. Pretty clever and probably effective.

Click to expand...

I think there will probably be enough turbulence in the wheel well so that there will be moving air over all the surfaces. I keep somewhat equating the motion of the brake rotor/fan with the similar zero differential rotation speed of a WWI airplane propeller and rotary engine. (I could be wrong though. )

I agree that water injection works. I just don't have enough of an overheating issue that I want to carry around the added weight of the water and tank/pump assembly.

SAW Blades?

Had to do some digging through my files to find these approaches. There is a US patent on such an idea:

With a bit of effort you could fabricate something I'm sure.

Formula One made a few moves a while back:

Cut and paste the URL and there is the story there - they dropped some of these as being unsafe - flying off the cars I guess can be a bit of a problem.
Here is a close up of the Ferrari version:

And, a Porsche:


The BBS set looks like this:


Suppose the C4 Saw blade wheels were supposed to do something?

Lots of grist for the mill. Most of the approaches I've seen have focused on reducing aerodynamic drag - not cooling. But if you could improve the cooling effects you could reduce the size of ducts, reduce drag from ducts, etc, etc.
Would be real sexy if clear lexan. Get the desired effect and not hide the wheel. Something like the Renault, McLaren, or Ferrari covers.
Cheers - Jim

Couldn't help it - you gt me so intrigued - I had to go Goggling...

Those are like 50- 60 bucks apiece. Cheaper than a 12 volt fan and duct.

http://www.youtube.com/watch?feature=player_embedded&v=y8t1RUWof4I

Would be useful to have a comparison with a duct and fan. But for light weight and few compilations, might be a winner.

phantomjock said:

.............And, a Porsche:


The BBS set looks like this:


..............- Jim

.

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There doesn't appear to be any pitch in the vanes of those things.
It seems more like a centrifugal impeller rather than a fan.
Is the back of the cone the secret to its success, in that the interior air volume increases as the radius increases?

I think with the odd offset of the C5Z wheels I'm using, a fan behind the wheel is probably my best/only option.

May buy the UltraCool Fans

For the price - and simplicity, I'm thinking of picking up a pair of these. Not near that point yet, but makes the project look like its moving along.


Those are like 50- 60 bucks apiece. Cheaper than a 12 volt fan and duct.

I note they don't have 5 x 4.75 - will contact and see if they have an undrilled set available.

Here is that video link again:
https://www.youtube.com/watch?feature=player_embedded&v=y8t1RUWof4I

Looks like a great place to take some pressure/tuft testing and measurement too.

Cheers - Jim

phantomjock said:

For the price - and simplicity, I'm thinking of picking up a pair of these. Not near that point yet, but makes the project look like its moving along.


Those are like 50- 60 bucks apiece. Cheaper than a 12 volt fan and duct.

I note they don't have 5 x 4.75 - will contact and see if they have an undrilled set available.

Here is that video link again:
https://www.youtube.com/watch?feature=player_embedded&v=y8t1RUWof4I

Looks like a great place to take some pressure/tuft testing and measurement too.

Cheers - Jim

Click to expand...

Respectfully, I haven't watched the video yet. We're out in the boonies with a metered data internet hookup, so videos boost up the data flow tally (and therefore the monthly bill), but I'll take a peek at it at the first (free) opportunity.
Thanks.

Oh - Yeah, I understand the throttled internet connection - deal with it all the time traveling.
Here is a quick pic that shows the flag blowing in the breeze:


Called the outfit. The fans are made slotted to fit from 5x 4.5 - 5 1/8 rotors. The fellow I spoke with was good to point out there can be problems with street cars. Seems there needs to be about 3/4" (maybe bit more) space from the face of the rotor hat back to the caliper for clearance. Also, about 2 1/2 inches on the outside to clear the spokes on the wheel. May be a go/no-go. I asked if they had measured the flow. They tried, but the rotor kept screwing up their info. Just, "Its a lot of wind..."
I'm going to do some measuring and see what fits - or not.

Cheers - JIm

One "advantage" I'm hoping to realize with this setup is that the fan vanes will be near the rotor periphery rather than near the outer rotor friction surface. My rotors are 11.75" OD (to fit under my stock C3 street wheels), while my track wheels are 16" ID (17" wheels). I'm hoping the fans will pull the air out of the rotor OD vents, while I try to direct air from under the car up to the rotor center.