I'm bouncing around the idea of planning a 2gph water injection nozzle in each brake duct. I've found some examples of this done with success on racecars in the past, however have seen very little current data. I'm willing to be the lab rat here.

Any thoughts from NASIOC?

-Duncan

you need more cooling?

I say go for it!!

Are you planning to trigger flow demand based off of current from a brake line pressure sensor? It could be variable and progressive.

How did you come up with 2GPH flowrate per brake (assuming just the fronts)?

did you already consider a fan? Someone suggested that those "electric turbochargers" use model jet airplane engines. I looked into them and you can get over 850 scfm from medium-large units that fit in a 3" tube. They don't build pressure very well and bigger units require too much power to justify as a supplemental turbocharger, but that should be more air than typically flows in brake duct hose at >70 mph. Could do some math...

Frank

I've never done a water cooled brake system but I would imagine you'll only see a worth while benefit from injecting water into the rotor hat area or inject into an airstream the feeds into the rotor hat area.

did you already consider a fan? Someone suggested that those "electric turbochargers" use model jet airplane engines. I looked into them and you can get over 850 scfm from medium-large units that fit in a 3" tube. They don't build pressure very well and bigger units require too much power to justify as a supplemental turbocharger, but that should be more air than typically flows in brake duct hose at >70 mph. Could do some math...

Frank

he already has a fan on there.. hahah thats why i asked if he needs more cooling.

When you are not racing, you can adjust the nozzles to spray your tires with soap water, and do AWD burnouts without fear of breaking your shizz.

My only theoretical concern would be if the mist/air temp is too cold, you might do some warping damaging due to the rapid change in temp. I'm thinking going from glowing red rotors to spraying them down with a garden hose as an extreme example...

My only theoretical concern would be if the mist/air temp is too cold, you might do some warping damaging due to the rapid change in temp. I'm thinking going from glowing red rotors to spraying them down with a garden hose as an extreme example...

I did the basic math and at rotor temps over a 1000 degrees the water will be steam long before it touches the rotor face.

-Duncan

I say go for it!!

Are you planning to trigger flow demand based off of current from a brake line pressure sensor? It could be variable and progressive.

How did you come up with 2GPH flowrate per brake (assuming just the fronts)?

I picked 2gph out of a hat. It seemed a reasonable size based on the flowrate and tank sizes needed to sustain 45 minutes of operation. I'm going to dig through the Trackmate data and see how many minutes of braking I do per x driving time. I'll use Summit Main for a data point since it's the worse out of all the tracks I drive.

I was going to use a simple on/off using the brake switch to keep the cost and complexity down.

-Duncan

you need more cooling?

Wouldn't hurt. My rotor temps are still hotter than I'd like. Before the next track day at a minimum I'm going to .

Remove the fans from the primary ducts (restriction at speed)

Hook them back up to the lower RCE ducts (currently not hooked to hose)

This shold give me both a low and high speed system.


Doing the water injection would be cheap using parts from Mcmaster and I just thought it would be interesting to compare how well it works.

-Duncan

Hey Dunk,

I did some research on this a while ago. You need the nozzles to be fairly close to the beginning of the ductwork as opposed to right next to the rotors.

-Clint

Hey Dunk,

I did some research on this a while ago. You need the nozzles to be fairly close to the beginning of the ductwork as opposed to right next to the rotors.

-Clint

Clint,

Return my call when you get a chance.

-Duncan

Well, they do this alot in the big semi truck racing down under. But i know for awhile (maybe they still do) WRC cars had watercooled calipers as in water flowed through them.

There was some talk awhile ago and some people brought about the hypothesis of steam forming under the pads and causing loss of braking power.

Quick temp fluctuations have different effects on different materials. Also, different brake compounds work more effectively at different temperatures. So, finding a pad that can handle quick thermal cycling and do its job effectively.

Good luck and let us know how it works.

When you are not racing, you can adjust the nozzles to spray your tires with soap water, and do AWD burnouts without fear of breaking your shizz.

this.
needs to happen

Why not go to the 4" fans with the 3" reducer?

Why not go to the 4" fans with the 3" reducer?

You're no fun. :(

I don't have the room to package it all in front of the brake duct inlet. I'm debating putting the 3" fan parallel to the main duct, with a y junction into the main pipe. This would probably involve the least fabrication.

-Duncan

Duncan, why are you having so many brake cooling problems? How much does your car weigh? How big are your rotors? What pads do you use?

I figure our cars can't be too far off on weight and top speed, and I have no problems with brake fade.

Hey Dunk,

I did some research on this a while ago. You need the nozzles to be fairly close to the beginning of the ductwork as opposed to right next to the rotors.

-Clint

This would make sense. Applying some sort of cooling fluid directly to the surfaces of the caliper or rotor could cause the metal to expand and contract to fast and to much This could cause the metal to crack. This is a really good idea though. You've got to post some pics when you work out the details. I wonder if there is way to use a flexible bladder?

why not just have a small nozzle spray something like C02 on it?

Duncan, why are you having so many brake cooling problems? How much does your car weigh? How big are your rotors? What pads do you use?

I figure our cars can't be too far off on weight and top speed, and I have no problems with brake fade.
Problem is subarus are very front heavy so the front brakes do most of the work. I've gone through countless brake setups up front, including several sets of rotors, a couple different calipers, and a ton of pads. I still have my stock rear rotors and calipers (5 years old) and they are completely fine.

Duncan, why are you having so many brake cooling problems? How much does your car weigh? How big are your rotors? What pads do you use?

I figure our cars can't be too far off on weight and top speed, and I have no problems with brake fade.

As Dan said, Subaru's are tough on brakes.

Car weights 3250 - race weight
Rotors are 13.3x1.26.
58% of the weight is on the front of the car.

It's not a fade issues as the brakes hold up fine. I'm just going through front rotors a lot quicker than I'd like. VIR is not so bad, but Summit Main kills them.

-Duncan

Problem is subarus are very front heavy so the front brakes do most of the work. I've gone through countless brake setups up front, including several sets of rotors, a couple different calipers, and a ton of pads. I still have my stock rear rotors and calipers (5 years old) and they are completely fine.

I've had the same set of race pads in the rear for about 6 events now. I've never replaced the rear rotors.

I'm on the fourth front caliper setup. :)

-Duncan

I want to see the water injection too, buuut, have you considered switching to one of the newer ceramic-based pads like the Ferodo DS2.11's? I understand the ceramic-based stuff is gentler on rotors. Since you say the rotor temps aren't too high, you may have room to switch to a softer pad. How hot is "not too hot"?

If you're running stoptech's you could switch to the 355mm rotor, assuming you use 18" wheels...

Frank

When you implement the water system use the aquamist jets, they are by far the best spray pattern Ive seen, at even low pressures.

I want to see the water injection too, buuut, have you considered switching to one of the newer ceramic-based pads like the Ferodo DS2.11's? I understand the ceramic-based stuff is gentler on rotors. Since you say the rotor temps aren't too high, you may have room to switch to a softer pad. How hot is "not too hot"?

If you're running stoptech's you could switch to the 355mm rotor, assuming you use 18" wheels...

Frank

Where did I say the rotor temps weren't high? I'm not getting any fade with the current pad (DTC 70) but my rotor temps are well north of 1300F.

I have two sets of CCW 17x10 wheels. I'm not willing to switch to 18's at this point.

-Duncan

very interesting how much weight distribution can affect brake rotor temps.

very interesting how much weight distribution can affect brake rotor temps.

Wally,

Do you run any ducts other than the factory Z06 stuff?

-Duncan

As Dan said, Subaru's are tough on brakes.

Car weights 3250 - race weight
Rotors are 13.3x1.26.
58% of the weight is on the front of the car.

It's not a fade issues as the brakes hold up fine. I'm just going through front rotors a lot quicker than I'd like. VIR is not so bad, but Summit Main kills them.

-Duncan

How are you "going though" are you wearing them? or cracking them?

Wally,

Do you run any ducts other than the factory Z06 stuff?

-Duncan

Last time I checked He ran a 3" hose to the rotor, from an aftermarket duct.

I just have the duct and no hose.

If it's rotors you're tearing through I have a few ideas I've been working on, but not had a chance to implement. We were going to try it on the one lap car, but didn't have a chance. I'll call when I can.

Wally,

Do you run any ducts other than the factory Z06 stuff?

-Duncan

each side has hose that goes straight to the inside of the rotor.

1300 degrees should be nothing to worry about with a good set of rotors. If you are going to do something like this, just be careful not to overcool the parts which will actually accelerate the cracking process. Iron does not like rapid temperature cycles so you are much better off maintaining your max temp and having slight fluctuations over a couple hundred degrees through out the lap than having big spikes followed by long cooldowns. Road America for example is a high speed, hard braking track that is known to be hard on brakes. Many of our race teams actually have to close off their ducts to reduce cooling to make sure the rotors dont cool down too much between braking events which causes the rotors to crack prematurely.

There are some good questions being asked, but as it stands, it desnt seem like youre giving us enough info about your setup and the actual problems you are having to help determine what the best solution for you is.

I would also be careful about purposely spraying water out on track, some track organizers may not allow that or feel it is safe, regardless of how careful you think you are being with the setup.

How are you "going though" are you wearing them? or cracking them?



Last time I checked He ran a 3" hose to the rotor, from an aftermarket duct.

I just have the duct and no hose.

I'm cracking them. Starts as small cracks that grow throughout the day until eventually they are big enough you can feel them with your finger nail. I can try and snap some pictures.

-Duncan

I'm using temperature sensing paint, however the range I'm in all the colors look the same, so I don't have an exact temp. I know it's hot enough to glow bright red.

What information would you like about my setup? I'll provide everything I can give you.

Brake setup is a Coleman front rotor. 13.3 x 1.26 with an aluminum hat (Wilwood)

Calipers is a Forged Superlite (Wilwood). Pads are .8" thick (running DTC-70)

Currently have a 3" duct going from the from bumper straight to the rotor center with a quantum motorsports brake inlet. There are currently fans installed inline with the duct, however as mentioned above I think I'm going to remove them so they aren't an impediment to flow. If I reinstall them it will be parallel to the air stream.

I'm not having any fade issues or boiling my brake fluid. I'm just experiencing poor rotor life due to cracking. Unfortunately I can't afford to replace my 17" wheel setup with 18's at this point due to cost. I have well over 7K wrapped up in wheels and tires. So I suppose I've got more time than money. :)

-Duncan

1300 degrees should be nothing to worry about with a good set of rotors. If you are going to do something like this, just be careful not to overcool the parts which will actually accelerate the cracking process. Iron does not like rapid temperature cycles so you are much better off maintaining your max temp and having slight fluctuations over a couple hundred degrees through out the lap than having big spikes followed by long cooldowns. Road America for example is a high speed, hard braking track that is known to be hard on brakes. Many of our race teams actually have to close off their ducts to reduce cooling to make sure the rotors dont cool down too much between braking events which causes the rotors to crack prematurely.

There are some good questions being asked, but as it stands, it desnt seem like youre giving us enough info about your setup and the actual problems you are having to help determine what the best solution for you is.

I would also be careful about purposely spraying water out on track, some track organizers may not allow that or feel it is safe, regardless of how careful you think you are being with the setup.

dunk, I'm not sure if I've asked this yet but have you cryo'd the rotors before? I know truck guys who haul all the time swear by it...?

Pictures of the current ducting.

http://photos.ellisfamilyalbum.com/cache/car-stuff/my-subaru-impreza-project/Winter%202008%20Projects/Feb%2024/Feb%2024.jpg_595.jpg

http://photos.ellisfamilyalbum.com/cache/car-stuff/my-subaru-impreza-project/Winter%202008%20Projects/Dec%2013/Winter%20Project%20008.jpg_595.jpg

http://photos.ellisfamilyalbum.com/cache/car-stuff/my-subaru-impreza-project/Winter%202008%20Projects/Jan%2020/Jan%2020%20002.jpg_595.jpg

http://photos.ellisfamilyalbum.com/cache/car-stuff/my-subaru-impreza-project/Racing%20Events/NASA%20Summit%20Main%20Nov%2008/_11X6694.JPG_595.jpg

dunk, I'm not sure if I've asked this yet but have you cryo'd the rotors before? I know truck guys who haul all the time swear by it...?

Have not.

Duncan

Co2 cooling ftw.... you may crack everything but it will cool them and it's pretty exotic

Do you happen to know the plate thickness and/or air gap of the rotors you are getting from coleman? If you are cracking rotors that easily, it would seem that they are the issue, not necessarily the way you are cooling them. Start by seeing if you can get parts with thicker plates and sacrifice some air gap...that should help a lot with the longevity.

I agree that fans are probably not helping you at speed and are probably causing an impedence. I saw your build thread and aerodynamically it looks like they would cause more harm than good except for when the car is at low speeds.

Do you happen to know the plate thickness and/or air gap of the rotors you are getting from coleman? If you are cracking rotors that easily, it would seem that they are the issue, not necessarily the way you are cooling them. Start by seeing if you can get parts with thicker plates and sacrifice some air gap...that should help a lot with the longevity.

I agree that fans are probably not helping you at speed and are probably causing an impedence. I saw your build thread and aerodynamically it looks like they would cause more harm than good except for when the car is at low speeds.

I can certainly measure it and post the information.

-Duncan

Try talking to Gary Sheehan or Jaime Montesalvo (brokenwrx) or call easystreet. They did it on the ESX car didnt they?

Try talking to Gary Sheehan or Jaime Montesalvo (brokenwrx) or call easystreet. They did it on the ESX car didnt they?

They did what?

lol, what are we talking about again ;)

they sprayed water on the rotors.

http://forums.nasioc.com/forums/showthread.php?p=13405976&highlight=water#post13405976

How do you and boost junkie compare speed wise on main? Within spitting distance? What kind of brakes does he have and how is his wear compared to yours? Cracking makes me think thermal shock. I wonder if you're cooling the brakes down too much between zones so, they're getting shocked every time you jump on the brakes.

Boost junkie is on yellow 6 piston 355mm StopTechs. Hes just now getting new rotors after more than a full season.

MK, as far as thermal shock goes, those are my thoughts as well which is why I asked about plate thickness and air gap. If the plates are thin with a wide air gap, the manufacturer is trying to minimize weight and maximize airflow. These are good things when the demads arent so great, but when pushed hard on a racetack with lots of grip and high speeds, more thermal mass is needed to absorb and dissipate heat. Also more material is needed to maintain strength in the parts.

How do you and boost junkie compare speed wise on main? Within spitting distance? What kind of brakes does he have and how is his wear compared to yours? Cracking makes me think thermal shock. I wonder if you're cooling the brakes down too much between zones so, they're getting shocked every time you jump on the brakes.
We are extremely close, within a tenth of each other. My Stoptechs did very well last season, I only had issues when I let the rotors wear down too far and one of them cracked. My pad wear seems to be pretty good though. I'm considering installing a second pair of ducts with fans just for Summit but I'm going to wait and see how everything goes with fresh rotors.

Here's a shot of the rotor.

http://photos.ellisfamilyalbum.com/zp-core/i.php?a=car-stuff%2Fmy-subaru-impreza-project%2FBrake+Ducts%2FImproved+Brake+Ducts&i=Brake+Ducts+070.jpg&s=595

lol, what are we talking about again ;)

they sprayed water on the rotors.

http://forums.nasioc.com/forums/showthread.php?p=13405976&highlight=water#post13405976

Wow,

Who knew?

-Duncan

Another thought i had, was the interaction of the steam, moisture and the race compound brake dust. Ive had race pads and moisture react and etch into the wheel surface.

From a glance and rough comparison or putting a rotor next to my computer screen, the coleman parts definitely have a lower internal vane count and likely narrower plates/wider air gap than a 332x32 StopTech rotor. That lack of thermal mass is defeintely your issue at this point. Ideally you should look into a lager setup with either wider rotors or take the step up to 18s and 355mm rotors.

We went through all this with the Harman Motive/ JC Meynet time attack STi and got to the point that larer parts were the only option.

If you can, compare your lap times to world challenge TC cars...those those cars are limited to 17" wheels, Toyo R comps, most of which are under 3000 pounds with drivers.

See here: http://www.world-challenge.com/files/competitors/2009_TC_Appendix_A_Ver_3.pdf

You cant really compare the WRX since they havent been running in the series competitively for some time

If you are within a few seconds of their times in a car with 3-400 pounds more weight, wider and sticker tires and more power, you can see how the brake requirements would need to go up pretty quickly.

Ok guys - here's what I've been thinking of trying.

1) shot peen the rotor faces with graduated sizes of shot going from large to small, and upping the velocity with each smaller shot
2) REM polishing the surface to help smooth it back out
3) Get a lance and spray the inner vanes with a thin layer thermal dispersant

As far as I know I don't know of anybody doing this, nor have I ever heard of anybody doing this.

My thinking is as follows -
Peen to help keep cracks from forming, and compress the surface
Polish to clean up the surface after the peen
dispersant to try and get the heat out of them more quickly

Now, what I don't know is if the rotor gets hot enough to destroy the work that the peening does.

Have not.

Duncan

If you wanna try it, I could probably get it done for free at the lab I use.

Worth a try.

Here's a shot of the rotor.

http://photos.ellisfamilyalbum.com/zp-core/i.php?a=car-stuff%2Fmy-subaru-impreza-project%2FBrake+Ducts%2FImproved+Brake+Ducts&i=Brake+Ducts+070.jpg&s=595

Hey guys, I dont make it over to Motorsports all that often and I understand that air cooling of the rotors is a fairly common technique. But I was wondering about couple of issues.

Do you know the temperature difference between the cooled side and the uncooled side of the rotor? because that might give prolonged internal stress to the rotors, as you have non uniform cooling between the sides.

Did you have similar rotor wear and rotor fatigue issues before you did the cooling ducts?

Have you tried different rotors with this exact setup, as the cracking of these particular rotors might be because of their overengineered thermal properties and a different metal composition maybe more forgiving to non-uniform cooling.

As for water cooling, you'd have to make sure its a uniform spray pattern, cooling the rotors uniformly otherwise you're having exaggerated cooling stresses.

Pls excuse the long post... I'm just trying to read and learn
~Duncan

Awesome thread!

I'm wondering if the temp difference is too great that it'll crack the rotor even with all the treatment. We've had problems with cracked rotors that we are still trying to find an solution for. We've tried using fans inline with the duct, which worked great when the car is sitting in the pits to prevent boil-over, but on track I believe it's actually a restriction.

I know the SWGT ESX car tried water sprayer to solve their brake fade issues one year, but from what I remember, it didn't make a huge difference..

Someone mentioned the semi-truck racing using water sprayer to cool the brakes, but I thought they still ran the air assisted drum brakes? Since the drum rotors dont' have veins, they might be able to get away with the temp shock..

Could all the rotor cracking be cause by a faulty pour at the foundry? We did have a set of rotors that lasted forever with minor surface cracks, but as soon as we changed them out, we started noticing bigger surface cracks and even cracks through the veins.

thoughts? ideas?

Tommy

Hey guys, I dont make it over to Motorsports all that often and I understand that air cooling of the rotors is a fairly common technique. But I was wondering about couple of issues.

Do you know the temperature difference between the cooled side and the uncooled side of the rotor? because that might give prolonged internal stress to the rotors, as you have non uniform cooling between the sides.

Did you have similar rotor wear and rotor fatigue issues before you did the cooling ducts?

Have you tried different rotors with this exact setup, as the cracking of these particular rotors might be because of their overengineered thermal properties and a different metal composition maybe more forgiving to non-uniform cooling.

As for water cooling, you'd have to make sure its a uniform spray pattern, cooling the rotors uniformly otherwise you're having exaggerated cooling stresses.

Pls excuse the long post... I'm just trying to read and learn
~Duncan

The idea of the cooling duct is to shoot it right at the center of the rotor hat, and have the air forced out of the veins, so I don't think the inside and outside have a major temp difference, thats if you have even pressure from both sides of the caliper pistons.

we've found that we had a brake line routing issue from the master cylinder that caused the front right to be about 70 degrees hotter than the front left, but surpising enough both rotors show the same amount and depth of cracks. Which leads me to believe that it might be a manufacturing fault..

The idea of the cooling duct is to shoot it right at the center of the rotor hat, and have the air forced out of the veins, so I don't think the inside and outside have a major temp difference, thats if you have even pressure from both sides of the caliper pistons.

we've found that we had a brake line routing issue from the master cylinder that caused the front right to be about 70 degrees hotter than the front left, but surpising enough both rotors show the same amount and depth of cracks. Which leads me to believe that it might be a manufacturing fault..

Thanks for the explanation.
As for the manufacturing fault it makes sense, since little changes (e.g. ~0.5%) in the composition of the metal, give huge changes in the microstructure of the metal, which in turn drastically changes the thermo-mechanical properties. It would be interesting to see what their quality control standards are... I'm probably just over analyzing since I'm used to looking at stuff on the microscopic level...

Thanks for the explanation.
As for the manufacturing fault it makes sense, since little changes (e.g. ~0.5%) in the composition of the metal, give huge changes in the microstructure of the metal, which in turn drastically changes the thermo-mechanical properties. It would be interesting to see what their quality control standards are... I'm probably just over analyzing since I'm used to looking at stuff on the microscopic level...

I don't think you're over analyzing it.. I wish manufacture's Q/A could be more strict, then again, I can appreciate their need to keep cost down. I'm just hoping we can figure out an elegant and simple solution to this..

on an side note.. we experienced an rotor failure at Mid-Ohio with Goto's Grand AM ST Legacy.. it absolutly DESTROYED that corner of the car.. Rim, tire, upright, control arm and etc.. I would hate to see that to anyone.. luckily no one was hurt..

Could all the rotor cracking be cause by a faulty pour at the foundry?


Tommy,

I don't think this is the issue. This is the second set of rotors, with 4 months separating the orders. I had similar issues with the last setup and smaller rotors.

It would interesting to get the weights of the STOPTECH rotors. I know it doesn't cover all the bases, but it would serve as a really rough comparison of thermal capacity.

If it's a rotor design issue, I'd be happy to switch to another brand. I don't have the capability to run any larger than the current size 13.3 x 1.26 unless someone wants to buy two sets of CCW wheels from me. :)

Anybody have any data on Coleman racing rotors. I couldn't find much outside their own website.

-Duncan

If you wanna try it, I could probably get it done for free at the lab I use.

Worth a try.

If I gave you a set next week, when could you have them back to me?

-Duncan

Is there some special about cryo treating parts? Like dipping them in Liquid Nitrogen or is it simply sticking them in a freezer?

Here is a link to our commplete rotor data sheet. Im not sure the wilwood setup would be compatible due to what looks like a wider pad annulus but its hard to say:

http://www.stoptech.com/images/AeroRotorDataSheet.jpg

I doubt that this is a quality issue, just what happens when rotors get too hot. Think of it like cooking 2 steaks on a hot grill, one that weight 10oz and one that weighs 6 oz. The mass of the the larger steak will cause to heat more slowly and go longer before getting heat saturated. Likewise, the larger steak will cool more gradually.

Metals in general dont like rapid heating and cooling cycles so having more mass will help to mellow that whole process out. We have found that ~900 degrees F is the magic number when it comes to rotors...you either want to run abobve it or below it. When you cross over that threshold reapeatedly, the structure of the rotors breaks down more rapidly and cracks happen much faster. Also, the speed at which that threshold is crossed can also make a difference. By having more thermal mass, the temperatures swings are less abrupt and it takes more energy and time to reach the temp extremes.

For example, our VP of sales used to work for an Indy car team...at road america, they had to change rotors after each practice session as they would crack. This was because they would do a few hot laps, pit and then do more hot laps. This caused the rotor to go through rapid heating and cooling cyles which led to cracking. When it came to race time, a new set of identical rotors were installed and they had no problem lasting the complete race and looked better than the 1 session practice rotors. The rotors stayed much hotter for a longer period of time but since it was not so drastic of a temp swing, they help up much better.

What is happening here is that the rotors are getting very hot, very quickly during braking events, then cooling down very rapidly. These temps are moving through the entire rotor assembly very quickly affecting the entire disc, not just the friction plates which is why they are not lasting very long.

Since our parent company purchased PowerSlot, we now have their cryo systems and will be doing some dyno testing comaprisons in the future. Im not sure of the exact process but its a multi cycled low to high temperature swing that takes place over 24 hours. Liquid nitrogen is used to get the parts into the -200 degree F range.

Lower quality parts tend to have better reults post-cryo than higher quality parts which dont see as much of a benefit.

i think you are over cooling the brakes between pedal applications
try block off half the brake intake cooling duct and see what that does - i know its not scientific but seems to make sense in my head, or get rotors that are more metal than vanes

Here is a link to our commplete rotor data sheet. Im not sure the wilwood setup would be compatible due to what looks like a wider pad annulus but its hard to say:

http://www.stoptech.com/images/AeroRotorDataSheet.jpg

I doubt that this is a quality issue, just what happens when rotors get too hot. Think of it like cooking 2 steaks on a hot grill, one that weight 10oz and one that weighs 6 oz. The mass of the the larger steak will cause to heat more slowly and go longer before getting heat saturated. Likewise, the larger steak will cool more gradually.

Metals in general dont like rapid heating and cooling cycles so having more mass will help to mellow that whole process out. We have found that ~900 degrees F is the magic number when it comes to rotors...you either want to run abobve it or below it. When you cross over that threshold reapeatedly, the structure of the rotors breaks down more rapidly and cracks happen much faster. Also, the speed at which that threshold is crossed can also make a difference. By having more thermal mass, the temperatures swings are less abrupt and it takes more energy and time to reach the temp extremes.

For example, our VP of sales used to work for an Indy car team...at road america, they had to change rotors after each practice session as they would crack. This was because they would do a few hot laps, pit and then do more hot laps. This caused the rotor to go through rapid heating and cooling cyles which led to cracking. When it came to race time, a new set of identical rotors were installed and they had no problem lasting the complete race and looked better than the 1 session practice rotors. The rotors stayed much hotter for a longer period of time but since it was not so drastic of a temp swing, they help up much better.

What is happening here is that the rotors are getting very hot, very quickly during braking events, then cooling down very rapidly. These temps are moving through the entire rotor assembly very quickly affecting the entire disc, not just the friction plates which is why they are not lasting very long.

Very interesting info!!

My comment on quality was not directed at Stoptech, since we've ran TRD/Stoptechs on the Scion and did not see any signs of cracks or failures even after the 25hr of Thunderhill! The drivers never once complained about any brake issues, But the heat cycle would make sense on our time attack car (different brand of brakes) since we only run a few laps at a time.


keeping the heat in the rotors perhaps to keep it from heat cycling as much.. but can also boil fluids and burn pads.. time to goto carbon discs? :lol:

Do you happen to be Steve Ruiz? Gary Sheehan introduced me to Steve awhile back and I've been bugging him ever since at events! :lol:

Tommy

No, but Ive been here since 05. Had dinner with the GST guys at Claim Jumper at Fontana Redline last year...were you there?

Carbon ceramic rotors are actually another interesting topic since they actually run hotter than iron...means you have to direct your cooling more to the calipers and pads instead of the rotors. Also, they dont expand or contract like iron so you need to allow for the hats to float since they are the parts that change dimensions with heat.

Since the OP mentioned no pad of fluid fade issues, it would seem that they could handle higher sustained temps, even if the rotors, ball joints and wheel bearings cant.

From a glance and rough comparison or putting a rotor next to my computer screen, the coleman parts definitely have a lower internal vane count and likely narrower plates/wider air gap than a 332x32 StopTech rotor. That lack of thermal mass is defeintely your issue at this point. Ideally you should look into a lager setup with either wider rotors or take the step up to 18s and 355mm rotors.

We went through all this with the Harman Motive/ JC Meynet time attack STi and got to the point that larer parts were the only option.

If you can, compare your lap times to world challenge TC cars...those those cars are limited to 17" wheels, Toyo R comps, most of which are under 3000 pounds with drivers.

See here: http://www.world-challenge.com/files/competitors/2009_TC_Appendix_A_Ver_3.pdf

You cant really compare the WRX since they havent been running in the series competitively for some time

If you are within a few seconds of their times in a car with 3-400 pounds more weight, wider and sticker tires and more power, you can see how the brake requirements would need to go up pretty quickly.

Here's the measurements from the rotor.

Plate width - .325 or 8.25mm (about the same as stoptech 332 or 355 rotor)
Vane width - .600 or 15.24 mm (again, not too far off the stoptech setup)

I'll try and get a weight later.

Here's a picture of the rotor after two track weekends (last at Summit Main)

http://photos.ellisfamilyalbum.com/zp-core/i.php?a=misc&i=IMG_3129.JPG&s=595

http://photos.ellisfamilyalbum.com/zp-core/i.php?a=misc&i=IMG_3130.JPG&s=595

-Duncan

If I gave you a set next week, when could you have them back to me?

-Duncan

Probably about 10 days until they are back in your hands.

They look like they just got used up to me, go wider or go bigger, its really all you. Any way of going to 35mm wide rotors?

Just for comparison, here is your rotor and BoostJunkie's rotors...look familiar?

http://photos.ellisfamilyalbum.com/zp-core/i.php?a=misc&i=IMG_3129.JPG&s=595

http://www.stoptech.com/images/Cracked.jpg

They look like they just got used up to me, go wider or go bigger, its really all you. Any way of going to 35mm wide rotors?

There's definitely room to go wider. It's just a matter of seeing what's out there.

-Duncan

This is interesting that you guys have having the rotors crack so fast.
What kind of brake compound is being used?


This is what the StopTech rotor looks like after about 10+ events, using the Hawk DTC-70 Compound. The rotor has some heat marks, but no cracks.
http://theattack.rallysportdirect.com/wp-content/gallery/events/dsc_0212_rs.jpg

I'm using a 295 R6 tire and the car is very fast. I'm probably asking more of the braking system than you are.

-Duncan

I'm using a 295 R6 tire and the car is very fast. I'm probably asking more of the braking system than you are.

-Duncan
Did this occure after a race? or after just doing several days of testing?
Im surprised that a rotor would crack that fast only after 2 days of track use. Considering that you have quite a bit of brake work done to keep them cool(brake ducts and so forth). What brake pads where you using?

We run everything from the RE-01r, to Hoosier, up to Michelin Blue Cup tires(make R6's look like winter tires), and everything in between. We dont use any brake ducts on our system, and it holds up perfectly fine. Only time I ever had issues was last weekend after doing 7 time attack laps, and boiling the fluid ( got lazy and did not change it sense last season).

Kirill
RallySportDirect.com

Are you guys on a 332 or 355mm setup?

Did this occure after a race? or after just doing several days of testing?
Im surprised that a rotor would crack that fast only after 2 days of track use. Considering that you have quite a bit of brake work done to keep them cool(brake ducts and so forth). What brake pads where you using?

We run everything from the RE-01r, to Hoosier, up to Michelin Blue Cup tires(make R6's look like winter tires), and everything in between. We dont use any brake ducts on our system, and it holds up perfectly fine. Only time I ever had issues was last weekend after doing 7 time attack laps, and boiling the fluid ( got lazy and did not change it sense last season).

Kirill
RallySportDirect.com

It was over two weekends, or five days of track use. Didn't start noticing the cracks until the second weekend at Summit Main. It's a pretty hard track on brakes. 1.20x lap with two hard braking zones and two more moderate ones.

-Duncan

I hate to be Nancy Negative but I don't think the water jets will work. You said that math you ran leads you to believe that the water will not even get to the rotors prior to it vaporizing. How is it going to cool the rotor if it isn't coming in contact with the rotor. I would guess that the water could cool the air around the rotors and therefore cooling the rotors a very small amount but not enough to cool them any significant amount.

I believe that for water to be able to significantly cool the rotors it would need to be enough flow for the water to come in contact with the rotor but not high enough to cause water to drip on the track.

I don't have an idea for a solution to your problem, but I really doubt water is the answer.

IIRC you checked your racing organization's rules to ensure that the use of water is permited. I remember reading through either NASA or SCCA rules for AutoX and they expressly stated that the use of water on track was prohibited. The use of water for cooling tires or intercoolers would be permitted on the staging grid only. You may want to double and triple check prior to installing something that is prohibited.

There's two things that the water will do, and why you want a fine misting.

1) The obvious cooling of the air. it won't be much as you're already shoving in relatively cool ambient air.
2) Increase in density. This is the big one. You're shoving more mass of stuff (air and water vapor) through the rotor. A fine mist will lead to a greater "spread" of the water and even though it will vaporize before hitting the rotor it soaks up a lot of heat to do that.

It was over two weekends, or five days of track use. Didn't start noticing the cracks until the second weekend at Summit Main. It's a pretty hard track on brakes. 1.20x lap with two hard braking zones and two more moderate ones.

-Duncan
What kind of temperatures are the rotors being taken to? Im assuming around 850+ or so, of the metal is cracking.
I am note sure if you have seen how F1 has there brakes set up. But what they do is feed air directly into the top of the caliper, above the pads. This requires allot of tire clearance, but if you are able to keep the pads cool, you in hance would keep the entire system much cooler.

I believe that for water to be able to significantly cool the rotors it would need to be enough flow for the water to come in contact with the rotor but not high enough to cause water to drip on the track.


You guys remember your high school physics? I'm thinking "heat of vaporization" where there's a huge ramp in the amount of heat required to convert water to vapor whereas just changing water's temp doesn't require much heat at all. I'm just thinking that even a mist would suck significant heat out of the entire system as it's vaporized.

I've been wondering about the contact patch of the pad to the rotor. It looks pretty narrow. The contact patch on stock brembo's is 2.5" across the rotor (from the inner shiny to the outer edge). I wonder if a narrow patch is causing high peak temps in the center of the contact area. I notice the rotors with the bad cracking have a distinctive blue color in the center of the contact area. What's the chance your pads are bending so, you're not getting full contact? I've bent pads before. The center of the pad was noticably thinner than the outer edges.

I was wondering if this could be caused by braking style. I notice in your last video Dunk that you brake pretty early going into one. There's probably 5 mph difference in our top speeds on main's straight but, I brake significantly later even on my street tires. With your 295's I'd have expected you to be able to dive deeper before braking than me. You seem to be on the brakes for a long time entering 1. Wonder if it would be worth comparing your video to Boost Junkies and see which of you brakes longer into 1?

Hopefully this will clear a few things up in regards to using water jets to cool the brakes.

Richard Lamb at Aquamist built me a water cooling system for the Element Time Attack car are a few years ago based on what some of the WRC teams were doing in the past. The system was based off of the Hydramist system we use for the engine except that the water injection rate was based on a 2D map in the Hydra. It was tuned based on vehicle speed and duty cycle (of the High Speed Valve) with the trigger being the brake switch. At certain speeds the water would not inject but as speeds increased we could alter the amount of water spray.

Ultimately I never used the system as I was able to accomplish what I really needed by going with a Stop Tech 355 mm rotor and very good ducting. The other issue was having to carry the weight of a gallon of water, running the lines safely, and the space all that requires.

Two small jets were used per caliper (finer mist with .3mm) and I was told it was critical to spray at the caliper and not the rotor itself. The evaporation of the water is what's removing the heat from the entire area and the water does not need to make contact with either the caliper for the rotor to be effective.

My 08 WRX "Street" class car using Brembos has major temp issues so I may adopt this system on that car if a set of fans doesn't do the trick.

Hope this helps.
Phil
Element Tuning

What kind of temperatures are the rotors being taken to? Im assuming around 850+ or so, of the metal is cracking.
I am note sure if you have seen how F1 has there brakes set up. But what they do is feed air directly into the top of the caliper, above the pads. This requires allot of tire clearance, but if you are able to keep the pads cool, you in hance would keep the entire system much cooler.
850? I wish :lol: My rotors run well in excess of 1000 degrees...how far above depends on the track and conditions. In terms of cooling, it's definitely more effective to feed air to the center of the rotor than the top of the caliper. Doing both would be nice but packaging constraints would make it difficult to get a decent amount of air to the caliper. This weekend I'm going to work on making shrouds for my ducting to prevent fresh air from escaping rather than being directed into the center of the rotor.

You guys remember your high school physics? I'm thinking "heat of vaporization" where there's a huge ramp in the amount of heat required to convert water to vapor whereas just changing water's temp doesn't require much heat at all. I'm just thinking that even a mist would suck significant heat out of the entire system as it's vaporized.

I've been wondering about the contact patch of the pad to the rotor. It looks pretty narrow. The contact patch on stock brembo's is 2.5" across the rotor (from the inner shiny to the outer edge). I wonder if a narrow patch is causing high peak temps in the center of the contact area. I notice the rotors with the bad cracking have a distinctive blue color in the center of the contact area. What's the chance your pads are bending so, you're not getting full contact? I've bent pads before. The center of the pad was noticably thinner than the outer edges.

I was wondering if this could be caused by braking style. I notice in your last video Dunk that you brake pretty early going into one. There's probably 5 mph difference in our top speeds on main's straight but, I brake significantly later even on my street tires. With your 295's I'd have expected you to be able to dive deeper before braking than me. You seem to be on the brakes for a long time entering 1. Wonder if it would be worth comparing your video to Boost Junkies and see which of you brakes longer into 1?

All interesting ideas. Pads are wearing straight. I only have two weekends at Summit Main so there's some room for improvement on compressing the braking zones.

-Duncan

All interesting ideas. Pads are wearing straight. I only have two weekends at Summit Main so there's some room for improvement on compressing the braking zones.

-Duncan

Dunk - I gave your dude a call. I'll get some rings in, and see what I can do.

-Clint

I was wondering if this could be caused by braking style. I notice in your last video Dunk that you brake pretty early going into one. There's probably 5 mph difference in our top speeds on main's straight but, I brake significantly later even on my street tires. With your 295's I'd have expected you to be able to dive deeper before braking than me. You seem to be on the brakes for a long time entering 1. Wonder if it would be worth comparing your video to Boost Junkies and see which of you brakes longer into 1?




I watched the video as well and thought that towards the middle of it that he started braking really early into 1. But it seemed that after 3 laps or so of braking early he started diving much deeper into the corner again.

I thought this was due to the vibration problem that he was having in the corners or that he just wanted to slow down a bit to give the brakes a chance to cool down and then started to get back on it again.

I guess Duncan is the only one who can answer that.:lol:

Yeah, I was kind of reluctant to say anything. I didn't want to sound critical.

That is why i didn't want to say anything either.:lol:

At least you race in a car. I race in a computer chair.:D

Well not many if any of you are running as low of a lap time either. I brake really early compared to most of you going into turn 1 but I'm also doing 160 mph! LOL

If the rate of temp change, as ESmooth discussed, is the problem, then braking more gently for a longer period of time may be better on the rotors. Depending on driver skill, it can also be better for laptime, as it can prevent over-slowing.

-Mike

I watched the video as well and thought that towards the middle of it that he started braking really early into 1. But it seemed that after 3 laps or so of braking early he started diving much deeper into the corner again.

I thought this was due to the vibration problem that he was having in the corners or that he just wanted to slow down a bit to give the brakes a chance to cool down and then started to get back on it again.

I guess Duncan is the only one who can answer that.:lol:

I was slowing down to let the tires come back. Also had a thin set of pads and was concerned a little about heat transfer. You can't slow down too much though, otherwise they get too cool. I was using a 20+ heat cycle old set of autocross A6's I got used. Probably not the best choice but I didn't want to pitch them. :)

-Duncan

Yeah, I was kind of reluctant to say anything. I didn't want to sound critical.

Doesn't bother me, it's the purpose of a forum. You know as well as anyone though that things can be a little different from the drivers seat. It's difficult to get a good sense of what's going on in the car.

I've been meaning to post the traqmate data from my fast laps. I'm coasting a little off the braking zones due to lack of track familiarity but my rate of decel is consistent. When the tires start to get overheated or have too many heat cycles their grip under braking gets worse and worse. I'll be out there in July doing some testing during the Trackdaze event with a set of new R6's so it will interesting to see the changes.

-Duncan

That is why i didn't want to say anything either.:lol:

At least you race in a car. I race in a computer chair.:D

Is it a fast computer chair?

Is it a fast computer chair?


Its the fastest computer chair this side of the James.:lol:

I figured you were slowing down for a reason. With as much experience as you have behind the wheel of a race car, I would find it hard to believe that you would all of a sudden start p*ssy footing the braking zones for no reason at all.

Another question.

I'm going to hook up the second set of lower brake ducts so I'll have 2 3" hoses to the rotor. Is it worth putting the fans on the second set of ducts so I'll have one with fans and one without? Or should I leave them off all together?

I'll be doing this regardless of the decision on the water injection.

-Duncan

I think you need to throw some Tempilaq or Genesis on your rotors next time out. On an aside, I have one and a half spare sets of water cooled tarmac assemblies, and I would be willing to part with one assembly if you are interested; though this would leave you to source the second and to either build or buy the plumbing/radiator/pump kit ( which was more expensive than the brakes, if I recall ). Rodney @ SWS can hook you up with whatever bits of kit you still needed if you wanna go that route...


SLR-

I think you need to throw some Tempilaq or Genesis on your rotors next time out. On an aside, I have one and a half spare sets of water cooled tarmac assemblies, and I would be willing to part with one assembly if you are interested; though this would leave you to source the second and to either build or buy the plumbing/radiator/pump kit ( which was more expensive than the brakes, if I recall ). Rodney @ SWS can hook you up with whatever bits of kit you still needed if you wanna go that route...


SLR-

I put genesis on the rotors. They running above 1400F. I'm not sure exactly what the temp is as I'm in the band with the three very similar yellow colors.

-Duncan

Dunk - I gave your dude a call. I'll get some rings in, and see what I can do.

-Clint

Just saw this. Sweet. I'll have the other set of rings cryo treated. I have a few sets of hats so I can do some testing at the next track day and see what the temp difference is. I'll paint a few areas of the rotor up and we can see what the temp differential is between the plates and vanes.

-Duncan

Got approval from the national director for this modification. :) For those of you that know things about Water Injection, do you think I'll be okay with the 1gpm pump, or do I need the 1.8gpm one.

-Duncan

Cool!!

I look forward to seeing what you can come up with.


Edit: Why are you thinking of running a pump that has a lower capacity than the nozzles that you plan on using?

Cool!!

I look forward to seeing what you can come up with.


Edit: Why are you thinking of running a pump that has a lower capacity than the nozzles that you plan on using?

The pump is rated in GPM. The nozzles are GPH

Reading > You. :)

-Duncan

Got approval from the national director for this modification. :) For those of you that know things about Water Injection, do you think I'll be okay with the 1gpm pump, or do I need the 1.8gpm one.

-Duncan

Cool :cool:

Just had a thought. You might want a master on/off switch for the water pump. I'm thinking foot on the brake pedal in grid and pre grid. Without an off switch you could drain your tank and leave a puddle.

I Love following your build.

Cool :cool:

Just had a thought. You might want a master on/off switch for the water pump. I'm thinking foot on the brake pedal in grid and pre grid. Without an off switch you could drain your tank and leave a puddle.

I Love following your build.

I'm planning on adding a master switch for those very reasons. I also want to easily be able to switch the system on and off.

-Duncan

Is there a way to make a scaled down version of those fan/mist systems they use in outdoor sporting events? We had them when I worked at Discount Tire and they used a very high pressure pump to get atomization of the water into the air.

The pump is rated in GPM. The nozzles are GPH

Reading > You. :)

-Duncan


Sí señor. Mi Inglés no es tan buena.:lol:


Is there a way to make a scaled down version of those fan/mist systems they use in outdoor sporting events? We had them when I worked at Discount Tire and they used a very high pressure pump to get atomization of the water into the air.

If I am not mistaken those kits normally run upwards of 1000psi. And I woudl think that it would get pricey using something that can withstand those types of pressure as well as withstanding the temps that the hose will be subjected to.

Disclaimer: I have been wrong before. Please reference earlier posts in this thread.

lol, you can just hear all the gears crunching from all the enginering ,spreadsheets being made slide rules flinging around.

lol, you can just hear all the gears crunching from all the enginering ,spreadsheets being made slide rules flinging around.


Old people.:D:alien:

Just saw this. Sweet. I'll have the other set of rings cryo treated. I have a few sets of hats so I can do some testing at the next track day and see what the temp difference is. I'll paint a few areas of the rotor up and we can see what the temp differential is between the plates and vanes.

-Duncan

I think they are still going to see the same peak temps. The question is how long will they hold that peak, and will they be able to withstand them.

This first round I don't think I'm going to do the thermal dispersant on the vanes. Just the surface treat to try and keep it as apples to apples as possible.

Since my pretty yellow calipers are now a yellowish brown, I'm looking into different options for refinishing them. The two things I'm looking at are hard anodizing and thermal dispersant coating. I have a feeling the hard anodizing will be prohibitively expensive and I'll end up with the thermal dispersant. I haven't had any trouble with boiling the fluid since I switched to Stoptechs but every little bit helps.

Since my pretty yellow calipers are now a yellowish brown, I'm looking into different options for refinishing them. The two things I'm looking at are hard anodizing and thermal dispersant coating. I have a feeling the hard anodizing will be prohibitively expensive and I'll end up with the thermal dispersant. I haven't had any trouble with boiling the fluid since I switched to Stoptechs but every little bit helps.

I actually have on my to-do list a note to call our supplier of the dispersant and find out if it can withstand the temps being put in without baking off.

-Clint

It would interesting to get the weights of the STOPTECH rotors. I know it doesn't cover all the bases, but it would serve as a really rough comparison of thermal capacity.


-Duncan

Weight of a StopTech 355MM ST40 kit

StopTech 355mm Rotor weight: 18.1 LBS
StopTech calipers and bracket: 9.74 LBS

A image of the OEM brembo rotor next to the StopTech.
http://theattack.rallysportdirect.com/wp-content/uploads/2009/03/img_0168.jpg

Im not here to hype up one brand over another. As if it was the case, I would be running the Brembo GTR kit ;)

As stated, makes me wonder if its the rotor manufacturing process with the composition of metals in the rotor that is causing this. We have several customer running StopTech kits on there race cars(everything form 3000lb AWD cars to HC), and we have yet to see there rotors crack. We only have to get them new rotors do to them getting worn down, and not from cracking.

On the flip side, have seen people run cheap ebay rotor and have them crack after 1 event. So it just makes you wonder.

Kirill
RallySportDirect.com

Found a company that builds these for pro race cars.

http://www.seinesystems.com/Mpc-TransAmBrakeDetail.htm

Weight of a StopTech 355MM ST40 kit

StopTech 355mm Rotor weight: 18.1 LBS
StopTech calipers and bracket: 9.74 LBS

A image of the OEM brembo rotor next to the StopTech.
http://theattack.rallysportdirect.com/wp-content/uploads/2009/03/img_0168.jpg

Im not here to hype up one brand over another. As if it was the case, I would be running the Brembo GTR kit ;)

As stated, makes me wonder if its the rotor manufacturing process with the composition of metals in the rotor that is causing this. We have several customer running StopTech kits on there race cars(everything form 3000lb AWD cars to HC), and we have yet to see there rotors crack. We only have to get them new rotors do to them getting worn down, and not from cracking.

On the flip side, have seen people run cheap ebay rotor and have them crack after 1 event. So it just makes you wonder.

Kirill
RallySportDirect.com


boost junkie's cracked the crap out of his 355 kit, but they were pretty worn down already.

boost junkie's cracked the crap out of his 355 kit, but they were pretty worn down already.

he had also used them for an entire season!!

Found a company that builds these for pro race cars.

http://www.seinesystems.com/Mpc-TransAmBrakeDetail.htm

I think the system we talked about will work well after looking at that example.

I actually have on my to-do list a note to call our supplier of the dispersant and find out if it can withstand the temps being put in without baking off.

-Clint
I saw that a couple of coating places are claiming their thermal dispersant is good for up to 2000 degrees. Can you let me know how much your guy charges to do all 4 calipers? I emailed a local coating shop yesterday and the guy could barely string together a coherent sentence in his reply so I'm a little hesitant to use them.

Old people.:D:alien:

lol yeah experience sucks
damn i guess they don t use the slide rule anymore huh

I saw that a couple of coating places are claiming their thermal dispersant is good for up to 2000 degrees. Can you let me know how much your guy charges to do all 4 calipers? I emailed a local coating shop yesterday and the guy could barely string together a coherent sentence in his reply so I'm a little hesitant to use them.

have you checked with Calico?

he had also used them for an entire season!!

Hence "pretty worn down already." :p

Found a company that builds these for pro race cars.

http://www.seinesystems.com/Mpc-TransAmBrakeDetail.htm

The Aquamist jets mist so fine in the .3 mm you don't need to mount them in the front part of the ducts. Also your avg speed is going to be substantially less than a Trans Am car and you may not have enough air velocity and therefore the water is just going to accumulate on the sides of the ducting.

The WRC setups that were used for lower speed have the fine mist nozzles closer to the caliper to ensure the water stays atomized. Just use the quality jets and you won't have a problem.

Hence "pretty worn down already." :p

what, I can't elaborate?;)

Hi Duncan. My name is Ed Nazarian. I remember seeing you post on the NASA boards about how youre building for ST2 and you had some questions about gutting. So, do you race in ST2 now? Or are you still building?

Well, im a fellow ST2 racer. I race with Socal NASA. You can check me out (self promotion proceeding :)) at:

http://www.ednazarian.com/

Would like to know how your STi is doing if youre racing now. Btw, do you have a website or any link regarding your ST2 STi? Sorry for not reading this thread entirely, so excuse me if i sound out of line, but maybe you should try different rotors. Ive been running Girodisc 2-piece rotors, and i cant be any happier right now. I would recommend you take a look. http://www.girodisc.com/ I have a friend with a 05 STi who also runs them. If you have questions i can put you in touch with my friend with the STi.

Dunk - I expect your rings to show up here any day for my experiment. I'll let you know what the dudes a MIS have to say.

Boost Junkie - Seems the company I purchased my TLTD from a while back is now owned by some new company so getting an answer from them has been.... difficult.

Boost Junkie - Seems the company I purchased my TLTD from a while back is now owned by some new company so getting an answer from them has been.... difficult.
Pretty sure I've decided to go with hard anodizing. It's not cheap but not nearly as expensive as I thought it would be. And since pretty much every race caliper I can think of uses it it can't be a bad thing.

Dunk - I expect your rings to show up here any day for my experiment. I'll let you know what the dudes a MIS have to say.

Boost Junkie - Seems the company I purchased my TLTD from a while back is now owned by some new company so getting an answer from them has been.... difficult.

Sounds good. I need to get the other set off to cryo.

-Duncan

Pretty sure I've decided to go with hard anodizing. It's not cheap but not nearly as expensive as I thought it would be. And since pretty much every race caliper I can think of uses it it can't be a bad thing.
You might get some heat resistance from it too, BTW. But you probably already knew that.

why not just have a small nozzle spray something like C02 on it?

Why not we just watch your rotors shatter.... hahaha :lol:

I posted this in my track car thread, but I hooked up the RCE ducts this weekend. Now I have 2 3" hoses straight to the center of the rotor.

I also removed both brake duct fans.

Picture of the inlets in the splitter.
http://photos.ellisfamilyalbum.com/cache/car-stuff/my-subaru-impreza-project/Brake%20Ducts/RCE%20Ducts/Picture%20005.jpg_595.jpg

Had to redo the splitter rear mounts to clear the new brake duct hose.
http://photos.ellisfamilyalbum.com/cache/car-stuff/my-subaru-impreza-project/Brake%20Ducts/RCE%20Ducts/Picture%20011.jpg_595.jpg

Straight piece of pipe in place of inlet fan.
http://photos.ellisfamilyalbum.com/cache/car-stuff/my-subaru-impreza-project/Brake%20Ducts/RCE%20Ducts/Picture%20023.jpg_595.jpg

Mounting nut welded onto subframe bracket. It's purpose is explained below.
http://photos.ellisfamilyalbum.com/cache/car-stuff/my-subaru-impreza-project/Brake%20Ducts/RCE%20Ducts/Picture%20028.jpg_595.jpg

To keep the hose from getting destroyed by the wheel at full lock, I fabricated these shields. They mount using the welded nut shown above and another on the bottom of the subframe.
http://photos.ellisfamilyalbum.com/cache/car-stuff/my-subaru-impreza-project/Brake%20Ducts/RCE%20Ducts/Picture%20029.jpg_595.jpg

Lower hose in place. You can see how the duct guard both protects the ducting and also helps to positively locate it.
http://photos.ellisfamilyalbum.com/cache/car-stuff/my-subaru-impreza-project/Brake%20Ducts/RCE%20Ducts/Picture%20031.jpg_595.jpg

Into the naca duct.
http://photos.ellisfamilyalbum.com/cache/car-stuff/my-subaru-impreza-project/Brake%20Ducts/RCE%20Ducts/Picture%20032.jpg_595.jpg

And the other side.
http://photos.ellisfamilyalbum.com/cache/car-stuff/my-subaru-impreza-project/Brake%20Ducts/RCE%20Ducts/Picture%20033.jpg_595.jpg

http://photos.ellisfamilyalbum.com/cache/car-stuff/my-subaru-impreza-project/Brake%20Ducts/RCE%20Ducts/Picture%20034.jpg_595.jpg

Here's a picture showing how the tire will rub the guard and not the hose.
http://photos.ellisfamilyalbum.com/cache/car-stuff/my-subaru-impreza-project/Brake%20Ducts/RCE%20Ducts/Picture%20035.jpg_595.jpg

-Duncan

Cool setup Duncan. Any pics of the inlet from under the splitter?

I know it's been a while since I updated this thread. I've spent the last five weeks in Georgia for work. Next track day is July 13th and 14th. In preparation I installed the water mister brake cooling system from Seine Systems.

Mist nozzle installed at head of brake duct. Nozzle points downstream towards the rotor.
http://photos.ellisfamilyalbum.com/zp-core/i.php?a=car-stuff%2Fmy-subaru-impreza-project%2FBrake+Ducts%2FWater+Mister&i=Water+Mister+002.jpg&s=595

http://photos.ellisfamilyalbum.com/zp-core/i.php?a=car-stuff%2Fmy-subaru-impreza-project%2FBrake+Ducts%2FWater+Mister&i=Water+Mister+001.jpg&s=595

Solenoid triggered off the brake switch
http://photos.ellisfamilyalbum.com/zp-core/i.php?a=car-stuff%2Fmy-subaru-impreza-project%2FBrake+Ducts%2FWater+Mister&i=Water+Mister+003.jpg&s=595

New switches. :) Master arm for the pump and solenoid.
http://photos.ellisfamilyalbum.com/zp-core/i.php?a=car-stuff%2Fmy-subaru-impreza-project%2FBrake+Ducts%2FWater+Mister&i=Water+Mister+004.jpg&s=595

Pump and pressure accumulator.
http://photos.ellisfamilyalbum.com/zp-core/i.php?a=car-stuff%2Fmy-subaru-impreza-project%2FBrake+Ducts%2FWater+Mister&i=Water+Mister+005.jpg&s=595

1 gallon tank should be plenty for up to 45 minutes of track time.
http://photos.ellisfamilyalbum.com/zp-core/i.php?a=car-stuff%2Fmy-subaru-impreza-project%2FBrake+Ducts%2FWater+Mister&i=Water+Mister+006.jpg&s=595

-Duncan

^^Nice setup!! :cool:

Lookin good!

Nice! Mine's not nearly as fancy as Ddunk's, but go the ducts in under the car. I'll never have any way to really measure they're effectiveness, but the brakes were awesome at NJMP. No sign of fade, ever. Definitely better than nothing. :)

http://i215.photobucket.com/albums/cc241/liquidsti/Car_Pics/DSCF5820.jpg

http://i215.photobucket.com/albums/cc241/liquidsti/Car_Pics/DSCF5822.jpg

http://i215.photobucket.com/albums/cc241/liquidsti/Car_Pics/DSCF5824.jpg

http://i215.photobucket.com/albums/cc241/liquidsti/Car_Pics/DSCF5827.jpg

http://i215.photobucket.com/albums/cc241/liquidsti/Car_Pics/DSCF5828.jpg

Very cool ideas :banana:

Thanks for sharing the progress pix - great to hear someone discuss their ideas and then actually do something! I only race a slow office chair and an even slower WRX wagon in AX.

My 2 cents:

Doing some random calculations, assuming all 2 gal per hour fully vaporizes (good assumption at 1400 degrees :lol:):

Each 2 gph mist will remove 4.7 KW of power (heat energy per time) from your brakes or a bit more than 6 HP from each brake rotor. Sounds like a pretty significant reduction in heat load to me. In other words, it should be equivalent to having a small (1.5 ton) AC unit on each side. This is just the latent heat of vaporization, not counting the existing cooling due to air flow.

Don't know the thermal mass of rotors and I'm too lazy to estimate their volume + heat capacity of iron to try and SWAG the temperature reduction but a good mechanical engineering student (aka, not me) could do that. I leave that as an exercise for the reader :) .

- Harry

post deleted, image of driving thru Quebec beaver pond won't load, LOL

[late to party]

Water injection into the brakes does work, and has been been used in many pro racing series in the past (Trans-Am in the 90s/early 2000's comes to mind). The ONLY reason why it is not used more often in more racing series is because it's not legal according to the rules.

Man, I feel like I've been sitting in class all day! My head hurts from all this detailed info, but this is why I love this site!

[late to party]

Water injection into the brakes does work, and has been been used in many pro racing series in the past (Trans-Am in the 90s/early 2000's comes to mind). The ONLY reason why it is not used more often in more racing series is because it's not legal according to the rules.

One of the benefits of running in a nearly open class. You get to play around and experiment with lots of things that would otherwise not be legal. :)

-Duncan

so you guys (duncan/mav1c) dont feel like the NACA ducts have a measurable neg effect on the splitters performance?

I would think the net effect would actually be beneficial. Locally right at the duct they would reduce the pressure and thereby decrease down force, but the total air flowing under the car after the duct woud decrease, increasing pressure. I could be dead wrong...

I kinda like those naca ducts since they might make routing the passenger side hose easier on my '08.

Frank

I would think the net effect would actually be beneficial. Locally right at the duct they would reduce the pressure and thereby decrease down force, but the total air flowing under the car after the duct woud decrease, increasing pressure. I could be dead wrong...

I kinda like those naca ducts since they might make routing the passenger side hose easier on my '08.

Frank

I'm clueless on this real racing stuff but if you want downforce at the front, don't you want low pressure under the car, which the venturi effect from the NACA ducts would cause, right? I thought the point of the splitters and air dams was to limit/prevent air from getting under the car. Wouldn't the ducts help pull what ever air does flow under the car out to the side (via the cooling duct and rotor), preventing a build up of pressure that would cause front end linft?

Seemed like win-win: pull air from under the car to increase downforce while cooling the brakes.

So, what gross conceptual error am I making here?

- Harry

I'm clueless on this real racing stuff but if you want downforce at the front, don't you want low pressure under the car, which the venturi effect from the NACA ducts would cause, right? I thought the point of the splitters and air dams was to limit/prevent air from getting under the car. Wouldn't the ducts help pull what ever air does flow under the car out to the side (via the cooling duct and rotor), preventing a build up of pressure that would cause front end linft?

Seemed like win-win: pull air from under the car to increase downforce while cooling the brakes.

So, what gross conceptual error am I making here?

- Harry

I'm pretty sure you're not missing anything, as that's my understanding of how it conceptually should be as well. Of course, in the real world we could be totally off, but I think this is the right idea.

I'm pretty sure you're not missing anything, as that's my understanding of how it conceptually should be as well. Of course, in the real world we could be totally off, but I think this is the right idea.

I think the biggest potential problem is that if you've got low pressure under the splitter, and high pressure in the wheel well, you might not get the right kind of flow through the duct. However, if the brakes work better and run cooler with the ducts, then air must be going the right direction.

-Mike

Has anyone ever looked into using brake fluid recirculators? It would take some custom plumbing, but they've been used for years in demanding circle track applications. Just curious.

Pat

I think the biggest potential problem is that if you've got low pressure under the splitter, and high pressure in the wheel well, you might not get the right kind of flow through the duct. However, if the brakes work better and run cooler with the ducts, then air must be going the right direction.

-Mike

not necessarily. in terms of cooling, the air could be going either direction and it would work the same. if you notice a difference with the water though, then its pretty obvious its flowing correctly.

Great ideas guys!

Anyone have a way to measer airspeed thru these brake ducts? I am thinking about one of those hand held spinner things to measure wind speed. It may be able to be put inline to test effectiveness of ducts.

I like the looks of the underside naca application but I am skeptical of it's function. A proper underpanel/flatbottom/whatever should speed up the air under the car in order to make a lower pressure zone and thus downforce. Trying to collect pressured air at this location might not be the best place to find pressurized air. The wind speed gizmo might be the best way to determine this.

JC

Great ideas guys!

Anyone have a way to measer airspeed thru these brake ducts? I am thinking about one of those hand held spinner things to measure wind speed. It may be able to be put inline to test effectiveness of ducts.

I like the looks of the underside naca application but I am skeptical of it's function. A proper underpanel/flatbottom/whatever should speed up the air under the car in order to make a lower pressure zone and thus downforce. Trying to collect pressured air at this location might not be the best place to find pressurized air. The wind speed gizmo might be the best way to determine this.

JC

How about a pitot / static tube? A very rugged way to measure fluid speed.

Those spinner things are known as an anemometer. FYI: Our MAF sensors are hot wire anemometers.

Wouldn't a pitot/static tube require precise aiming that might be difficult in a curving airstream such as brake ducts?

Could a maf sensor be integrated?

Nope, you are just looking for a relative number. A MAF is both delicate and has the same boundary layer issues measuring absolute flow. That's why there are issues with cheap intakes.

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Very interesting idea.

Something I would add to increase the air flow to the brakes... Fab a duct facing forward and mount it directly below the intake to force more air into the intake.

looks good. If I wasn't so lazy I would do this....