CMB Brake Duct Testing

[KKaWing]

Thanks for the real world testing. The suggestions seems to validate race car designs which funnel air into the center of the rotor so that it is expelled evenly through the venting in the center. If the inner side of the rotor was cooled several hundred degrees compared to the outer, then there appears to be plenty of airflow to work with. Now it's just a matter of designing a product that can get the air into the center of the rotor. That won't be easy with an axle in the way.

TF-Works did a pretty nice one for the 86's. Let me go dig up a picture.

^ Thanks ATL_BRZ

 

[Siestarider]

Wow great testing [MENTION=1391]Siestarider[/MENTION] ... How much larger of a hole would you consider 2.5"?

There is actually a pretty good size gap in rotor vent hub on back side if you inspect with CMB cooling ducts in place, only a "quarter moon" of the existing duct opens into that space. I am imagining a 2" inlet that flares to an outlet that opens into that gap, expanding as much up and down as toward the axle and sort of covering the exposed hub vent area on rear side. I can visualize it but am a lousy artist.

 

[Pete]

There is actually a pretty good size gap in rotor vent hub on back side if you inspect with CMB cooling ducts in place, only a "quarter moon" of the existing duct opens into that space. I am imagining a 2" inlet that flares to an outlet that opens into that gap, expanding as much up and down as toward the axle and sort of covering the exposed hub vent area on rear side. I can visualize it but am a lousy artist.

Do you think you can measure from the hub (closest part of the inner stock rotor exposed) to the far end of the the hole where the brake duct is? I am trying to figure out if this would work perfectly with the wilwood brake kit as the the rotor is larger than stock so it may line up perfectly to distribute the air to the inner vanes.

 

[Siestarider]

Do you think you can measure from the hub (closest part of the inner stock rotor exposed) to the far end of the the hole where the brake duct is? I am trying to figure out if this would work perfectly with the wilwood brake kit as the the rotor is larger than stock so it may line up perfectly to distribute the air to the inner vanes.

I measured everything when I installed the test duct. The CMB Racing existing 2" vent extends over the stock inner rotor hub vane opening 1/2" at max radius looking dead into inside of duct opening.

 

[Chuckable]

Do you think you can measure from the hub (closest part of the inner stock rotor exposed) to the far end of the the hole where the brake duct is? I am trying to figure out if this would work perfectly with the wilwood brake kit as the the rotor is larger than stock so it may line up perfectly to distribute the air to the inner vanes.

Was wondering the same thing. The existing set-up may work with the Wilwood kit. Siestarider, if you're scheduled to be at PBIR on March 26th we could take a look and see.

 

[Siestarider]

I finally got both sides of the car set up with CMB ducts and hoses to front fog vents. So night before Sebring

Drivers side

Passenger side

Drivers side

Passengers side

Blue = 750 F, Tan = 1000 F, Gray = 1250 F

So these ducts keep brakes cooler than stock tested last year at same track, stock setup ran over 1000 F both sides. These pics are before and after one 25 min session. Over 750 F and under 1000 F all outside rotor edges and right at or below 750 F insides at hub below swept area.

Drivers side duct modified by me to run more air into hub opening.

I cannot tell any difference between them. Just that both outside rotor faces ran a little cooler than inside rotor faces. Which leads me to believe the CMB ducts work well, do not excessively cool one side as some feared, and are not improved by my modification to driver's side.

This with OEM pads, Rival S tires, braking as late and hard as traction would allow. NASA runs HPDE 1 and 2 together, so there were plenty of obstacles, had to focus on sectors to get a clean virtual PB, so no mercy for the car. But often had three or four sectors in a row open for full bore. No fade in brakes during any of six sessions total.

 

[CMbuildz Racing]

I finally got both sides of the car set up with CMB ducts and hoses to front fog vents. So night before Sebring

Drivers side

Passenger side

Drivers side

Passengers side

Blue = 750 F, Tan = 1000 F, Gray = 1250 F

So these ducts keep brakes cooler than stock tested last year at same track, stock setup ran over 1000 F both sides. These pics are before and after one 25 min session. Over 750 F and under 1000 F all outside rotor edges and right at or below 750 F insides at hub below swept area.

Drivers side duct modified by me to run more air into hub opening.

I cannot tell any difference between them. Just that both outside rotor faces ran a little cooler than inside rotor faces. Which leads me to believe the CMB ducts work well, do not excessively cool one side as some feared, and are not improved by my modification to driver's side.

This with OEM pads, Rival S tires, braking as late and hard as traction would allow. NASA runs HPDE 1 and 2 together, so there were plenty of obstacles, had to focus on sectors to get a clean virtual PB, so no mercy for the car. But often had three or four sectors in a row open for full bore. No fade in brakes during any of six sessions total.

Thanks for the hard evidence that my ducts work... I love the thorough input you've been providing [MENTION=1391]Siestarider[/MENTION] it's much appreciated [emoji4]

 

[Siestarider]

Thanks for the hard evidence that my ducts work... I love the thorough input you've been providing [MENTION=1391]Siestarider[/MENTION] it's much appreciated [emoji4]

I was surprised my "improvement" to driver's side did not make a difference. Reading back over the data, I also suspect my prior single side test may not have been as air tight at the front facia as both vents are now that I glassed them in.

But what surprised me most is how well stock pads and rotors held up to Rival S grip under braking at Sebring. To me, that is the real test. Your ducts work.

 

[Siestarider]

Update after PBIR, Rival S tires produced better lap times than first track day this year, seemed to benefit from heat cycling. Plus lots of experimenting with tire pressures and temps with Joe's pyrometer. Side effect of better track tires is more brake abuse, later braking with better rubber, but still no fade at all with CMB cooling. This is confirmed by my last three laps of the day, all within 0.1 sec of each other and all within 0.5 of PB set before afternoon ambient 94F. Rival S have the reputation of heating up quickly and getting greasy with too much fast lapping, but my experience was after first track day, that did not happen again.

My tracking mentor Nick B says suspension is next upgrade from stock in the critical path of becoming quicker, so I am all in with Jerrick at Meister, ordered slightly custom coils that I can try stiffer Swift springs with. I purchased Chuckable's used WW fronts, but will not mount them until OEM brakes package fails to perform. With CMB cooling, that may not happen. Part of this is working tire pressures and temps seeking optimum set up. Which of course changes with ambient heat and track temps.

One benefit of changing out my failed actuator is I now know why my go foot is getting cooked with heater on full blast, drivers side heater ducts open on top of accelerator pedal. Next track day I will have custom duct to carry that heat past foot well and out window. Stubbornly sticking with stock heat exchangers until I cannot control track coolant temps any other way.

Passenger side of radiator shroud still bugging me, hate those flaps, may try just cutting them out and freeing up flow through radiator. Just not sure how DD will be affected.

All this experimenting has left my Cyborg on shelf, do not want to change too many variables at one time. When I cannot get quicker any other way, then time to add more hp. Still learning to drive, so suspension upgrade next, no hurry in theory but knowing i have 20% hp gain waiting to implement is tough to delay.

Plus with hood vents installed, I need to do some pressure and temp measurements to see what they are doing. So many ideas, too little time.

 

[OCS12]

Inside nose fog vent flange re-oriented parallel with fog light enclosure

New aluminum airbox under flange with 3" x 2" adaptor.

3" box and fitting interfered with IC. Cut box to smallest possible, still would not fit. Went to 2.5" x 2" adapter and built smaller box. Managed to get it all in place. with most of the original 3" fog vent duct still feeding 2.5" adapter.

For this approach, just go with 2" fog vent, or easier still, loose fog light and adapt to rear of fog light box. I spent way too much time trying to get the larger vent openings to work. I am running Cobb IC, in case your IC is different, clearance to side of the IC inlet hose is the issue.

The easy part. This pic loaded upside down.

I ran hose under the lower A arm, but I have undertray still on, new version, to support most of it. Running it between lower A and driveshaft and hanging it per CMB advice may be better option. Also loaded upside down, have to learn how to fix that with edit function.

Next is plenty of temp paint on both sides before track day. I also want to log both front wheels to see if TVC is a major factor tracking with LSD, if so, it could affect brake cooliing.

Thought I'd resurrect an old thread to share some useful info. This little guy solves all the issues Siestarider fought with for 2.5" ducting to the side of the fog lights. Woodstock W1042 2-1/2-Inch Universal Dust Port https://www.amazon.com/dp/B0000DD1F3/ref=cm_sw_r_cp_api_KWnXxb34RV1E3
No adapters needed, and with the angle, everything lined right up.

 

[Siestarider]

I followed a link to here Woods247 kindly posted in a newer thread. Read the thread and have no new information to offer, except that track performance remains the same and street obviously too.

There is another thread somewhere about how I turned the fake front facia vents into real ones and converted to 2" flex hose to feed brake ducts. But several other options exist.

 

[myothercarisa]

Hey @Siestarider , finding this thread and very keen on seeing the pictures you posted but seems image hosting is closed down. Seems like a long shot but any chance you could re-share somehow? Seems like you've got a great right up here.