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Brake duct inlets for NB's

Old 03-01-2017, 02:43 PM
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Default Brake duct inlets for NB's

I bought a singular motorsports brake duct kit but surprisingly noticed no one was selling inlets. What are people using? Designed and printed my own but i figured someone else was out there making something better.

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Old 03-01-2017, 06:44 PM
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Good idea.

Here's a few additional suggestions:

The top of the foglight recess is flat so you will get a better fit if you flatten the top:


I bought a set of DemonTweaks Air Ducts and trimmed them to fit:



Note: The Demon Tweaks grilles mount to the flat ridge in the duct.

I also made a backplate for the rear so that the pop-rivets have something to hold onto (they'd pull-through the bumper).
If you're attaching via bolts, you can probably just get away with large washers on the bolts since you don't want then to "pull through":


I would've liked the ducts to be deeper so that there was a longer section to clamp the hose to, mine are barely the width of a clamp:


Your ducts need to have a parallel section at the rear, not tapered, for the hose clamps to mount securely, otherwise they'll slip off.
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Old 03-01-2017, 07:08 PM
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Good feedback man.

I suppose i could flatten the top to get a few more MM of clearance. I just used 4 3mm machine screws to hold the inlet into the bumper.



My 2.5" hose has not arrived yet so i haven't got a chance to test-fit. I agree my taper at the exit may be insufficient - i added a little extra flare at the end which is hard to see so the hose clamp stays put.

I wanted to make sure i had an integrated screen to help prevent rocks and rubber at the track from entering the ducting and potentially tearing a hole.

Great job with your DIY btw.
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Old 03-01-2017, 07:29 PM
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Looks awesome, I was thinking about adding a mesh inlet when I do my ducts. I wonder if anyone ever had any issues with debris going into the ducting and getting stuck in the rotor.
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Old 03-01-2017, 07:35 PM
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Originally Posted by unplugged92 View Post
Looks awesome, I was thinking about adding a mesh inlet when I do my ducts. I wonder if anyone ever had any issues with debris going into the ducting and getting stuck in the rotor.
I spend a lot of time at the track and know especially when i'm behind someone on slicks i get a lot of rubber thrown at me. My big concern was having a duct get compromised then somehow damage a brake line. I saw a video recently of an EVO that had a brake duct get wrapped around a front axle, tear a brake line, lost all hydraulic pressure and then crashed due to no brakes. Obviously we don't have a front axles to deal with but when it comes to potential avoidable safety issues i thought this was cheap insurance and should prevent larger debris from entering the ducts.
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Old 03-02-2017, 12:46 AM
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Not a great photo, but the best I have at the moment.
I used an aluminum duct flange from Aircraft Spruce.
ALUMINUM FLANGES FOR DUCTING from Aircraft Spruce
I used the 4" to 3" flange, connected to a 3" to 2.5" straight silicone reducer, with a short piece of 2.5" aluminum tubing to connect the reducer to the 2.5" duct.
The 4" flange fills the fog light hole well.
The silicone reducer is sandwiched against the backside of the bumper cover with a couple of thin aluminum "L" brackets for a tight fit with no holes to drill.
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Old 03-02-2017, 02:12 AM
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Fwiw something that would rip your brake line out or brake duct hose out would demolish a 3d printed screen.

Also screens block more flow than you think.
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Old 03-02-2017, 08:27 AM
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Originally Posted by unplugged92 View Post
Looks awesome, I was thinking about adding a mesh inlet when I do my ducts. I wonder if anyone ever had any issues with debris going into the ducting and getting stuck in the rotor.
My duct hose vents into my Cold Air Box which has the air filter for the turbo in it - no way would I risk running without it.

As aidandj pointed out, the mesh will block a lot of air (supposedly household flyscreen mesh blocks 50% of airflow in your house).
The foglight recess will be a high pressure area when moving though so you're still getting a lot of air through it (ie. much more than 50%).
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Old 03-02-2017, 09:12 AM
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Originally Posted by aidandj View Post
Fwiw something that would rip your brake line out or brake duct hose out would demolish a 3d printed screen.

Also screens block more flow than you think.
The screen is not 3d printed it is stainless steel weave. I calculated a 40% reduction of air flow due to the screen but that's perfectly fine for my application with street tires.
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Old 03-03-2017, 04:14 PM
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