Brake cooling idea, need advice...

[Geert-Jan]

I have an idea for cooling the rear brakes.
But I am not an aerodynamic expert, nor do I have a windtunnel.

I am thinking of a Naca duct in the floor of the car (with or without an air scoop?) (see 3th photo, green triangle)
From there a flexible hose to the rear ventilated brake disc, through the recess of the suspension arm, since I don't think it has that much travel. Otherwise next to that. (see 3th photo, green dot)

What do you think?

 

[Jerry Irwin]

From my experiance with design and racing gt racing cars, the area under the car is low pressure so will produce no positive air flow thru the duct.
I am of course, open to be corrected.

Jerry

 

[Geert-Jan]

As I was saying, I am no expert, but I believe that there is a lot of airflow underneath the car. That's why in F1 cars the aerodynamic of the floor is at least as important as the rest of the car. The faster the air flow is whats creating the ground effect.

My GT3 also has air scoops onderneath for rear brake cooling:

 

[Geert-Jan]

And if I do a google search, there are a lot of race cars having naca duct is the floor

 

[Davidmgbv8]

The original GT40 side scoop provided air not only to the engine compartment, but also dumps out into the rear wheels. Is that not enough cooling?

 

[JP Verweij]

 

[Brian Kissel]

That’s some pretty exotic brake cooling. On cars with vented rotors, they tend to direct the air into the middle of the rotor. I guess this is the best way for a solid rotor. I like it.
Thank You for posting this.

Regards Brian

 

[Howard Jones]

Question #1. What do you intend to use the car for and what do you have now for brakes/tires/pads? ya........ thats twoish.......

Streetcar with streetcar tires and brake pads? You dont need to cool the rear brakes unless you are driving completely crazy on the street where it is impossible to get the rear rotors near 500-600F. If you are, stop doing that. You'll shoot your eye out kid.

Ocassional open track type events. These are ti[ically 30 min sessions. Unless you change to slicks and race pads for track days
I still think you will not need to vent the rear brakes. There just isnt enough time on track to really get them hot enough to need to cool them.

But..................... if you really want to know if you need them cooled then do this and see how hot things are getting. If you are changing to race pads and slicks then you will know, or need to know , the temp range the pads want as well as the tires. You will need to try and keep the pads in their
temp range. That can be hard to do on some shorter tracks especally with a mixed group (performance) of cars sharing the track .

But in any case, this stuff is very useful for a track car (waste of money on the street)

Temperature Indicating Brake Paint, 1 ounce Brush-in-Cap Jar | Pegasus Auto Racing Supplies

This temperature-indicating brake paint lacquer permanently changes colors as it reaches various temperatures.

www.pegasusautoracing.com

 

[Geert-Jan]

I mainly use the car for trackdays.
Last time out, was a very sunny, hot day.
The brakes got really hot, even the rims were hot.
That's why I decided to make brake ducts for front and rear.
My engine has not been overheating, so the cooling for the engine is good as it is. That's why I don't want to use the side scope for the brake, cause it might diminish the engine cooling.

 

[Ian Anderson]

How about the Mk11 top of rear deck scoops. Seen a lot on replica MK1 cars and in my opinion do not look out of place

 

[Brian]

There's high pressure right in front and to the leading edge beside the tire. And it's conveniently close to the brakes.

With a splitter and disfuser under the car should be low pressure, but it is flowing so the NACA should do something so long as it's not discharging into a very high pressure area.

 

[Randy V]

I’ve used 12v bilge blowers to boost the airstream to my rotors on a couple of my racecars.
Like this one -

Amazon.com

 

[Ian Anderson]

I’ve used 12v bilge blowers to boost the airstream to my rotors on a couple of my racecars.
Like this one -

Amazon.com

I used two of those mounted front of engine bay to keep air moving when stuck in traffic
Rated at 400 cfm they moved a lot of air past the headers and out the back

 

[Kev Farrington]

I don`t like the idea of ducts underneath which might allow debris like chippings etc to come into contact with the brakes.