what part would you like to see made for the z4?

[solo_the_lad]

i think you'd be surprised at the effectiveness of some front brake ducting, even if it does just blow air into the wheel well. it'll only hit the tyre if you're on full lock, but most trackday applications you're rarely turning the wheel more than a quarter turn, miles away from full lock like you'd need to do a three point turn. and that blanking panel is ripe for a trumpet of some kind, slight turn on it and then blast it straight at the caliper would be great.

e85 z4s have zero front brake cooling as standard, and pulling through air from a high pressure point like in front of the bumper would be very effective IMO. no need to protrude into the wheel well, just an angled vent would be blasting 80mph air at the brakes. at the very least it would stop the air in the wheel well becoming hot and stagnant - as i say, zero brake ducting as standard!

Don't forget that there is also a cooling gain to be had by extracting the air from the wheelarch, allowing cooler air to come in from outside, even if that is from around the wheel. Of course, this would ideally require a vent of some kind. For a trackday car you could cut slots in the rear of the wheelarch liner, perhaps covered with gauze mesh to reduce the crud build up behind the liner. Then look at a vent that could replace the side indicator. They are very easy to remove/refit, so you could even pop them back in for a legal trip to and from the track.

I like your idea of the rear vents, where do you think they'd exit though, just diagonally out of the side fender? Also would this be more effective than a top mounted vent in the fender like most people do I believe. Also side note, considered repurposing the side markers as well at one point, to be exhaust exits Figured it was too difficult to manufacture though, not to mention illegal

[enuff_zed]

I imagined them replacing the side indicators

[solo_the_lad]

Alright I may have come up with a much simpler idea for the brake ducts.

Exit will be here as previously discussed, angled up at the rotor.

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The tube will travel in a straight path to here where it will pass under the radiator, either on the right side of the rubber flap or through it, whichever one avoids the radiator plug.

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And the inlet will theoretically be here, or a bit to the right.

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So this method would be a relatively simple design, except for the inlet component. The benefit of this design is it will avoid needing to remove the bumper/ cut holes in the side of the plastic wall behind the bumper, and it would have a more direct air path. It would however require a cutout of the plastic grill on the part where that middle fin is, which could possibly look a bit strange if that fin is broken into sections around the air ducts. I suppose we don't necessarily need to cut into the grill at all, and just mount the duct behind it (will not have cool looking ducts tho). And lastly I'll have to figure out a material to make it out of, which currently I am leaning towards 3D printing for simplicity, cost, and weight. We can also use flexible brake duct tubing in-between the inlet/ outlet components to save on weight as well. Let me know what you guys think!