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Discussion Starter #1 (Edited)
There's a guy on eBay selling 3D printed bellmouth air intakes for $20. Any reason that wouldn't function just as well as a Breathe kit?

**for clarification, the main difference seems to be plastic vs aluminum.
 

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As long as the 3D plastic version is smooth they will function the same. Most 3D units require sanding to smooth the plastic lines left from the process.
 

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I think there's lots of reason to expect that the TTP Breathe can potentially perform a lot better than the typical 3D printed bellmouth. However, the chances you can recognize these differences on your bike are very small. If you were going with a 904 kit and big cams and big throttle bodies then the Breathe would likely be required (along with the cotton/oil air filter) for you to get all of the power you could potentially get at WOT / max RPM. But on a regular 865cc stock(ish) engine running 8K rpm redline I'm pretty sure you won't find the differences on any dyno.

That said, my bike with the TTP Tune 2 2:1 with a 3D printed bellmouth, TEC 2-1 exhaust and a UNI air filter ran a touch rich across the board, I wound up leaning it 5% and now it runs a touch on the lean side but not noticeably so besides making much better MPG and less black tailpipe. I have no doubt with the Breathe and a cotton/oil air filter it would run less rich due to more air available, and probably make a bit more power.
 

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Discussion Starter #4
I think there's lots of reason to expect that the TTP Breathe can potentially perform a lot better than the typical 3D printed bellmouth. However, the chances you can recognize these differences on your bike are very small. If you were going with a 904 kit and big cams and big throttle bodies then the Breathe would likely be required (along with the cotton/oil air filter) for you to get all of the power you could potentially get at WOT / max RPM. But on a regular 865cc stock(ish) engine running 8K rpm redline I'm pretty sure you won't find the differences on any dyno.

That said, my bike with the TTP Tune 2 2:1 with a 3D printed bellmouth, TEC 2-1 exhaust and a UNI air filter ran a touch rich across the board, I wound up leaning it 5% and now it runs a touch on the lean side but not noticeably so besides making much better MPG and less black tailpipe. I have no doubt with the Breathe and a cotton/oil air filter it would run less rich due to more air available, and probably make a bit more power.
Thanks 72. I'm at altitude and the bike already has a K&N filter, AI delete and higher flow aftermarket pipes. I'm not looking to make her a track bike, just want to make sure she can get the air she needs to be at her best.
 

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Well in your case I would maybe suggest get rid of the K&N air filter, which flows plenty of air, and plenty of dirt along with it. UNI filter flows nearly as much air and is way better at filtering dirt.

But I do think most of the benefits of the TTP Breathe will be realized when coupled with other mods to get more air through the cylinders, including increasing displacement and increasing RPMs.
 

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I have alway felt TTP was a bit crazy to ask what they want for thier intake. But I am also not much of a K&N "screen door" filters either. But, you pay your money and take your choice as the man said. ...J.D.
 

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I made one on the college 3d printer smoothed it off and fitted it; no reason to think it was any better or worse than the expensive one?
 
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Nice solution. Do you know if that's that a bolt-on fit or will it need some mods?
It's a double sided plenum. So you cut one half off. There a center part with two ridges, and the bell coming off both sides. Keep the two ridges as that's how it inserts into the plate. It's rubber and cuts pretty easy. Well, I guess my attempt was sloppy:



744257


744258
 

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I made one on the college 3d printer smoothed it off and fitted it; no reason to think it was any better or worse than the expensive one?
Yeah, I like the guy who makes the Breath kit, seems like a good sort and to be trusted. Still, not sure I've seen independent testing on how much better it performs. My common sense tells me these are pretty basic bikes with basic CVK36 carbs, not formula 1 machines. It's hard for me to believe that they are so sensitive to the nuances of the bellmouth that you'd notice a difference. Could be wrong, of course.
 

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Dimensionally equal there will be no change in flow characteristics or CFM between an aluminum or the 3D plastic bellmouths give they are both of equally smooth surfaces.

We used three different types, Aluminum, fiberglass and plastic in our flow laboratory. Technically every bellmouth will have slight variances in each of their individual performance results in a laboratory. Aluminum can have some variances due to temperature changing the dimension slightly over fiberglass & plastic.

Holy smokes ! BonnieBlack -- What the hell did you use to cut that with ? A claw hammer !!!! 😳 WOW ! 😃
 

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Those angles you see there were determined by a series of closed-form calculus equations designed to maximize air volume while optimally disturbing the laminar flow to get air to make the 90 degree turn it needs to enter the carbs. If you look closely, you'll see half of the cuts are setup to turn the air molecules in front of the left-hand carb, the other half contain angles that will cause the molecules to initiate the turn in front of the right hand carb. Getting exactly half the molecules into each carb is the trick.

I have to admit, after the first bottle of vodka I remained perplexed with the best way to proceed and was having a hard time with the math. But after the second bottle it all became crystal clear, and there is the result.
 

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Been running a 3D printed Bellmouth for a couple years now with zero issues.

Psy

Sent from my LG-H873 using Tapatalk
 

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Just to clarify, the TTP bellmouth ("Breathe") is not identical or even very close to the same shape as the common 3d printed bellmouths out there (including the one on my own SE). There is more different than the choice of aluminum vs. the printed plastic.

Also, it's unlikely the Polaris rubber bellmouth has the same shape as either the TTP Breathe or the 3d printed ones.

The pedigree of the 3d printed part's design is unknown (to me). It is certainly better than the factory snorkel, and better than running no snorkel with the hard corners, but it's almost certainly not optimized for this application.

The Polaris part is also definitely not optimized for this specific application but it might be optimized for a different application, such as a 2-stroke snowmobile with entirely different displacement and airflow requirements. A ~432cc single cylinder 2-stroke may have similar airflow requirements to the 360-degree 865 twin as long as you ignore max RPM.

The TTP Breathe is likely better-optimized for this application than the other alternatives, but my guess is that to see the differences between the TTP and either of the other two choices, you would likely have to have many additional mods. On an otherwise mostly-stock Bonneville, I think the Breathe is probably overkill and the Polaris and 3d parts are probably sufficient. On a 904 with big cams and p/p head and port matched exhaust etc. I think the Breathe would be critical under WOT and high revs. And if building one of those engines there's no reason you wouldn't spend the money on the Breathe... just put it in the package with the other bits from TTP for your project.

Frankly I think on a bone stock Bonneville the main difference between the stock snorkel and any of these bellmouth covers is noise.
 

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Never considered buying any bellmouth from anyone. When I started modding my bike after improving exhaust flow I removed the snorkel and air box baffle, had to increase main jet size. Later I cut out the air filter retainer opening to the same size as the filter opening, increased jet size more to 135. Enlarging the air box opening seamed to do more good (must have been more restrictive) than removing the internal baffle. I can't imagine a bellmouth making a measurable difference over carving the opening to filter size and if it did it would be at the very top of the RPM range. IMO.
 

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That thread has a key piece of information, which is that even before it was modified to make it larger, that bellmouth is included on snowmobiles that make 150hp at 8100 rpm, of course on a two-stroke triple 800cc.

Be cool if someone knew how to do the math to determine if this bellmouth was adequate dimensions for the 865 Bonneville. The displacement per intake stroke in the Bonneville is more but the rate would have to take into account the bore/stroke and piston speed. My gut tells me it is too small to make max power on a Bonneville without mods.
 
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