Brake Ducts

[jeffw]

I saw this and thought you guys may find it interesting....

Brake Ducts

[Joshie]

Interesting Jeff.

I notice that it is suitable for Porsche's but I wonder if it could be modified to fit the S4.

For £129 though, looks like great value - if it works [img]images/graemlins/gotmesome.gif[/img]

[Dippy]

Y don't u just run some pipes from your air con to blow cold air onto the brakes?

[s2driver]

Avoid assymetric brake cooling. It is better to let the disk cool naturally instead of forcing one side to cool quicker than the other: disk warpage is alomst guaranteed since the thermal strains would be huge if the brakes get very hot.

One of the major advantages of large disks is that you have more mass of material so that the disk temperature doesn't rise as much for a given energy transfer. Your brakes simply convert kinetic energy of the moving vehicle into heat: ducting is only required if you are putting more heat energy into the disk than they can lose through [mainly] radiative heat transfer between your braking maneouvers. Radiative heat transfer is proportinal to Temp^4 so the hotter they are, the faster they will lose energy naturally. Adding ducting promotes increased convective heat transfer and should only be advisable if you can deliver the airflow evenly to the entire disk.

If you are getting into temperature problems look at you pad and disk material selection first since the disk mass and material dictates its own temperature rise and the pad is the only thing that promotes conductive heat transfer to your brake fluid. AP Racing are one of several suppliers that offer high boiling point brake fluids which may be a more sensible solution if you have temperature problems and you are stuck with disk and pad material. I use some funky Castrol stuff which I stupidly can't remember the name of...doh!

You might get away with assymetric cooling if you are a gentle braker....but if that's the case you don't need to cool them! Disk vanes are shaped to suck air through the disk from the centre which is why F1 cars duct the air through the hub to the inside of the disk and NOT onto the disk surface. The best way is to 'feed' more air to the lowest air pressure point on the disk's vanes to increase convective transfer.

I have just fitted 360 mm RS4 disks and AP 6 pot callipers (my custom mod...pictures to follow!) to my S2 and did look at length into getting airflow ducted to the right place on the disk. It proved a major headacke to avoid the suspension components, driveshafts and maintaining full lock without clashes so I dropped the idea. It is very difficult to get proper cooling when a driveshaft is in the way as it is in our Quattro-transmissioned chariots.

My advice: be sure you "solve more issues than you create" with forced brake cooling.

Lee

PS The only Porsche brake cooling ducts that I have had a close look at were on a works GT3R. Car was apparently worth over £250K and the brake cooling was implemented perfectly as expected.....haven't had a good look at their road car systems.

[s2driver]

Just to avoid confusion....Jeffs link is for a system which is highly suited to the 2 wheel drive Porsches. Looks like a great value kit too, and is well implemented. I just think that it would be incredibly difficult to retro-fit to a 4 wheel drive car and still do more good than harm.

Lee

[jeffw]

I think that this kit is designed to force air into the center of the disc.

One of the problems that the S4 & RS4 appear to face is that the intercooler 'exhaust' is vented into the wheelarch area (not sure if the RS4 side vents relive this situation). This hotter than normal air cannot help with brake cooling. If we could duct cooler air into the wheelarch then this has got to help with brake temperature.

[Bushy]

I have been looking into this for some time and hope to have something fitted this week, or early next

I have ordered some parts from a VW Phaeton and hope to get this idea fitted as the Phaeton has ducted brake cooling as std

I got the idea from RS4.org and have a picture of someone else's install, sorry for this as I am not sure who gets credit

[img]images/rsul/12139-%7B01F3F8AB-7ABF-4A71-977A-8337334EC37D%7D_DSC00953%20%28Small%29.JPG[/img]

[Bushy]

However now looking at the Porshe offering I may try and get this to fit instead

[sitas3]

One of the problems that the S4 & RS4 appear to face is that the intercooler 'exhaust' is vented into the wheelarch area

This also affects the S3/TT as I've been considering this area too. The shape/styling of our bumpers doesn't help things brake wise. If you look at the Porsche Boxster S for example, the bumper design maximises airflow over the front brake discs for max cooling - even for the super porsche brakes on a car that weighs nearly 200kg less than the S3..

[s2driver]

[img]images/graemlins/thumbs.gif[/img] I would be very interested to see how you get on Steve. I would like to have a look at how it clears the driveshaft if you get it fitted.

Lee

[Carl]

hey bushy!

i get the credits. that was my idea with the phaeton parts. i have fitted them on several rs4 already. for more infos and pics contact me at: info@bauwerk24.de

greez
carl

[Bushy]

i thought it was you carl, was it successful or did the discs still warp? as you were only cooling one side of the disc?

[s2driver]

Your picture of the Phaeton ducts weren't clear but it looked like they ducted the air to the centre of the disk (the right place)...I might be wrong mind you.

[Carl]

it was much better than before but still not best, since i had the old audi discs. with the new audi discs it should be great. but i havn´t tried that because i mounted the movits. but i still have the phaeton air ducts. those do a great job and are necessary on the german autobahn if you speed like me allways full throttle when possible... [img]images/graemlins/audiS4black.gif[/img]

[s2driver]

So, where exactly is the air ducted? This mod looks very interesting if it works right.