John McM

I've had my C4 for a year now and am starting to push it hard at the track. At least hard enough that I'm making mistakes https://dl.dropboxusercontent.com/u/...-johnsspin.gif

The last session had brakes smoking and the front pads (Brembo) showed signs of overheating.

The question now is how to duct the brakes? Yes, I have ducts in the car, but they are for show as currently installed. Looking at the front space I can see a real adventure plumbing them up

Thoughts now are to other options. Has anyone put scoops under the car or even scoops in the rear indicator opening in the bumper?

964George

There's kits available
http://www.fvd.de/de/en/Porsche-0/96...Foglights.html
Plus I remember seeing a thread with detailed pictures of a Rennlister that fitted them...

964George

Check these out
https://rennlist.com/forums/964-foru...it-fitted.html
https://rennlist.com/forums/964-foru...-on-964-a.html

John McM

Thanks George. I had seen the FVD solution but was interested in effectiveness and other solutions. The links you posted gave some insights.

The three things I'm working through are:

1. How directed the flow has to be onto the disk/pads to be effective?

2. How best to direct that flow?

3. How to source that flow?

Right now I'm wondering why no one has put a scoop into the airflow under the car and fed it directly up to a nozzle attached to the brake backing plate. No cutting of the liner or other parts and no need to work around the wheel movement.

jcs_911

I have done the scoops under the A arms in the front. I bought the kit from OG Racing a number of years ago (I don't know if anyone even sells it now). There are basically 2 problems here. One is with a lowered track car, you are knocking off/hitting/cracking/scraping the scoops pretty often. I rebuilt my scoops a number of times with Kevlar fabric and aluminum on the bottom to replace the fiberglass of the originals. Made them larger, too. Which is the 2nd issue - there just doesn't seem to be enough air under the car to really cool the brakes with scoops (either the smaller original ones, or my modified larger ones) like that.

The good thing about the kit was that it had the adapters to duct the air to the eye of the rotor. I still use those.

John McM

Great info. So the front ducts are the best place to source the airflow?

HiWind

While not directly applicable, the topic is very well covered on 996 gt3 forum
...worth browsing those threads if you want to see how close, where, options etc..

m_a_saunders

I installed the FVD kit with fog lights which actually originates from TechArt. Fog lights are quite useful when driving in the dark...

jcs_911

Yes. The ducts that replace the fog lights. And get the biggest opening you can find. Run the hose from there to the brakes.

boxsey911

John, since having my ducts fitted (see link posted above by George) I've been very pleased at how the brakes have performed on track. The HP2000 pads have stood up very well with nothing like the signs of overheating that I see in your pic. However, I wonder whether the extra weight that you have at the front of the C4 might mean that you need more than ducting to help you out?

You might have to consider moving to Pagid RS29s which will cope with heat a lot better, albeit at about twice the price of the Brembos. And maybe you'll have to think about bigger brakes so that you've got larger pads and rotors to disperse the heat more. I've gone the route of 993 front brakes to make the brakes run even cooler but I'll admit that my decision to do this was made easy by getting some 993 calipers for a bargain price.

Gus

I have and am looking at the same issue - from all the measurements that I have pulled there is almost zero room on the front inside of the wheel well area to allow for ducting that would clear the wheel during a tight turn -( parking lot more so than track ) In a pure race car it may be interesting to run the ducting from the front through the frunk ( trunk area) and then turn it towards the center line of the wheel through the frunk body work. The ducting would be out of the wheels way, but could be focused on the center of the brake disk with appropriate designed adapters. Or- the curved scoop that is stock on the car can be increased in size, this would allow the air from the front fog light ducts to be turn to the brake disk without having to install ducting. The disk protective plate needs to come off. A protective shield may still be need for the sensors on the hub though. The rear is a lot easier as there are more options to work with, but cooling is not as critical.

John McM

Boxsey, I've been running against a C2 and I'm definitely carrying more weight than him so even more pressure on the brakes.

I was happy with the Brembos but I've changed to PFC 08 compound to see if I can get more bite. There are some interesting points coming out vis-a-vis ducting versus bigger brakes. I'm still unsure how effective general ducting is when racers direct flow very directly to the disk. As stated above the ducting area is very tight meaning little room to route ducting pipe to the disk. Maybe I will have to stump up for bigger brakes. Maybe steal the big reds off my
turbo 3.6

boxsey911

I'm glad I went for the ducting before I fitted the bigger brakes as I got to see the effect the ducting had in isolation. Even though the FVD kit is unlikely to be as effective as more direct ducting that is fitted to race cars, it's a sympathetic solution as there's no major surgery required to the car. I didn't make any measurements on the cooling effect (don't know how to) but what I did notice is that:

1. The brakes took longer to warm up to reach their optimum feel/bite.
2. The pedal was noticeably firmer at the end of 20 minute track session.
3. The pads were in visibly better shape at end of a track day.

So I'm pretty sure that the kit has provided at least some beneficial cooling.

As Gus mentions above, the front backing plates have been removed on mine as the FVD set up directs the air at the rotor face. i.e. the cooling would be less effective with the shields in place. I've also removed the backing plates on the rear calipers but am thinking of replacing those at the next rotor change because I think they might beneficial at the rear to shield the rotors from heat radiated from the exhaust.

Chiefyb

If it's any help this is what I came up with. The ducting goes straight to the center of the disc. No fouling during normal use





More info on the build here http://www.911uk.com/viewtopic.php?t...asc&highlight=

Gus

Chiefyb
Nice bit of kit - appears that you don't get any tire rub on the front hose sections. Looks as though you did have to flatten the hose some to allow this - Looks good and functional. How - much
Ref the shields: Boxsey911 - here is a poor Q pic that I took to show you the shield modification on the rear. The only component on the hub that needs protection is the sensor - so you can trim the shield back to a minimum. If you have larger disk you can use the old shield to protect the sensor just make sure it clears the disk by cutting back some of the rolled over lip. Do not worry about the heat from exhaust in this area as the wind will carry all to the rear of the car