This is what I am working with...I am trying to use some aluminum tubing to design some curved stacks that fit under the hood. I have not yet cut the outer ends to length(still need to determine exactly what the best length is going to be for this engine). Anyway, I have an inside diameter of about 47-48mm on this tubing....its a very unfortunate size for finding an aluminum bellmouth I can weld to the end of the tubes. I did try hand-forming a bellmouth...and while I think I could do it once...I dont think I could duplicate it six times with any sort of accuracy...so I am scouring the internet for existing bellmouths and came across this gem:
https://www.pegasusautoracing.com/productdetails.asp?RecID=31776
For several reasons this particular bellmouth isn't very appealing(bolt holes interrupt the bellmouth radius, its a rough casting, etc.....but at the same time it is very appealing because most importantly...you can bolt an airbox backing plate directly over the top which means you can get away with a VERY low profile air filter element...which is important because of the runner on the back passenger side being so close to the shock tower bracing(before cutting to length)...this also has the(very cosmetic) appeal of being able to remove the airbox and still have a show-quality velocity stack setup without a flange that interrupts the tubing. Obviously this particular product wont work because its badly interrupts function...but it DOES give me an idea, I could very well use some billet aluminum and fabricate some bellmouths of my own where the bellmouth extends another 3/4" past where this one does, allowing for a full bellmouth that would still allow a backing plate to slide over the bell and bolt to the flange(this would require either a wider bolt pattern, or only half a hole on the backing plate and the use of washers to make up the difference or something). The real goal I am trying for a bellmouth that will fit under a low profile filter, that the airbox is easily removed from and that doesnt leave unsightly flanges halfway down the tubing...all while not harming performance. Any thoughts on how best to accomplish this? Aside from this approach, the only other one I can think of would use a backing plate that is split, using something like this:
This is a split exhaust clamp, but you get the idea...the only problem with using a split backing plate is getting it to firmly clamp to the tubing. I suppose this is something I may have to design and make with a 3D printer in the end(a split backing plate that integrates 2 or 3 o-rings to clamp around the tubing and stay firmly in place) Any help on solving this is appreciated, I am sure there are many simple solutions I just haven't thought of.
Have a router? You could cut some from aluminum plate using a roundover bit after boring holes in the plate.
Then cut out the results and weld them into place. You could cut the backside of them on a lathe.
Another option?
3D print the bellmouths from ABS or CF filament.
+1 on the 3d printing. PA6 nylon or a polycarbonate blend will hold up to under hood temps just fine. If you need assistance with CAD or 3d printing in Nylon shoot me a PM.
RacetruckRon said:
+1 on the 3d printing. PA6 nylon or a polycarbonate blend will hold up to under hood temps just fine. If you need assistance with CAD or 3d printing in Nylon shoot me a PM.
I might well take you up on that...any recommendations on some free software that I can use to draw up what I need? A split backing plate is going to be ideal I think...but if you look at the first picture and the angle the cylinder offset forces the pipes to sit at, it will require oblonging the holes to maintain a parallel line with the valve cover(which will vary the ceiling inside the filter element, requiring a taller filter than otherwise...blah bah) This one is certainly a challenge.
Gingerbeardman said:
https://xcessivemanufacturing.com/replacement-hardware/intake-parts/runners-and-velocity-stacks.html
You're welcome.
Thanks, those stacks look almost perfect(aside from being cast anyway, but I can turn them to finish them easily enough, with any luck the casting isnt porous enough to cause problems welding)
Find something with a little smaller ID and trim it to fit. Make your own with a dimple die setup, possibly integrated into the wall of a plenum with an intake tube going forward to a filtered cold air source. If all else fails, a big flat "washer" will perform better than nothing.
In reply to Wicked93gs :
Definitely seems like a bit of a challenge, not impossible though. I think you can still get a hobbyist license of Fusion 360 for free. I pay $40 a year for an EAA membership and have a student version of Solidworks through them.
bluej
UberDork
2/21/20 8:52 a.m.
RacetruckRon said:
In reply to Wicked93gs :
Definitely seems like a bit of a challenge, not impossible though. I think you can still get a hobbyist license of Fusion 360 for free. I pay $40 a year for an EAA membership and have a student version of Solidworks through them.
Thanks for pointing me towards the right search terms (hobby license). I actually went looking for fusion for a new personal computer last night and was having trouble finding whatever Autodesk software was the current free version (taken a few different forms the past 5-6 years). For the OP, here's the direct link: Fusion 360 limited personal license
I made bellmouths by using large sockets as arbours in a press. I would just use a long tube, make the mouth and cut to length. Then do as many as you need.
This is the approx profile that worked OK
https://static.grainger.com/rp/s/is/image/Grainger/21WK73_AS01?$mdmain$
Paul_VR6 said:
I made bellmouths by using large sockets as arbours in a press. I would just use a long tube, make the mouth and cut to length. Then do as many as you need.
This is the approx profile that worked OK
https://static.grainger.com/rp/s/is/image/Grainger/21WK73_AS01?$mdmain$
That's a clever way to do it...any pictures of the final result out of curiosity? I could use scraps of tubing for that method.(Not that I have a press, but with aluminum being as soft as it is, I could probably come up with something...or just buy one...its another tool I find myself in need of often enough.)
fatallightning said:
Jenvey has some cool, but not cheap, bits. https://store.jenvey.co.uk/throttle-bodies-and-components/air-horns
Jenvey does indeed...not that I will ever order anything from them, they are in the UK....but they do have their US based distributor...Fox Injection:
They seem to offer this, which is 48mm ID...looks like it would accomplish what I want with no fuss at all...it stands off 19mm too...which means it won't impact airflow...a very good option...$35 a piece...but may well be worth it if it solves all the problems in one swoop...also provides some felxibility in being able to be unbolted to swap to longer horn lengths as needed.
Thanks for reminding me of Jenvey...I had browsed their air horns probably ten times and never saw this one.
