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Angled air horns for 40mm Weber DCOE


Juel72

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I have looked into having a set of curved air horns made from nylon using the rapid prototyping technique of Selective Laser Sintering. Went as far as commissioning CAD engineering blueprints and received a quote of around $600 for a set of four. Much of the cost is setup, so additional horns can be produced for around $150 each. In my case I will have long straight aluminum air horns coming off the slide throttle, with the curved portion only at the end. Nylon can be dyed any color fairly easily. Since we have not finalized geometry I am not sure if I will need to go this route or not.

Fred '74 tii

--Fred

'74tii (Colorado) track car

'69ti (Black/Red/Yellow) rolling resto track car

'73tii (Fjord....RIP)

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Thank you for all of your suggestions.

I really like the Alfa horns, but I really want to have a decent filter also.

Check the link, to see the quick solution I have been using all summer. I think it is time to make a more long term solution.

Maybe something like the TI could also be made

https://picasaweb.google.com/lh/photo/SbZosravF1czSMQ3Ik0gVMcLGcGN9xTpokKJIyrR778?feat=directlink

B/R

Juel

Located in Denmark

1975 BMW 2002 Twin Weber

2000 VW Passat TDI

1999 Nissan Micra (wife's shopping cart)

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Some theory info for ya' eurotrash...

"The air horn serves three main purposes; 1) To convert the pressure difference between bore and entrance into air velocity with the minimum of energy loss. 2) To act as the interface between the induction system and the atmosphere, i.e. the point at which pressure waves change sign and direction. 3) To complete the system to the required overall length. 


For ease of description the air horn may be considered in two parts; the 'flare' and the 'tube'; 
The main job of the flare is to spread the low pressure zone over the largest possible area - to reduce local pressure reduction - whilst guiding incoming air into the tube with minimum disruption or induced vortices. The flare should be shaped to encourage air to enter from the sides, but not from the rear, of the mouth. This is achieved by either finishing the mouth with a sharp edge when the arc is a little beyond 90 degrees from the air horn axis or by folding material back, parallel to the axis, when the arc is at, or just below, 90 degrees to the axis. 
The main job of the tube is to accelerate the airflow smoothly and progressively. This is best achieved by an exponential shape - i.e. one where the radius of curvature is increasing constantly until the angle of the sides matches the next part of the system, usually the throttle body. At the intake end this should blend smoothly with the flare.

It should be noted that the requirements for fuel injection and carburation do not always coincide and the best horns for one may not suit the other."

See more in these 2 attached PDFs:

Airflow basics + Induction Systems Tech

HTH,

Tom

Airflow Basics.pdf

induction systems tech.pdf

Where we goin’? … I’ll drive…
There are some who call me... Tom too         v i s i o n a u t i k s.com   

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i was looking for a ti airbox but would have to switch to a tii m/c for clearance. I'm going to fab an airbox to integrate with the alfa horns over the winter as I would like some kind of paper filtering element, maybe an oval cobra type filter? the foam socks kind of remove the nice aesthetic for me...like the old school look...

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The problem with a filter is that it WILL mess with the fuel wave that

stands outside the carb at speed.

I have had all sorts of problems with that.

Thus, I made the biggest, ugliest thing I could think of-

it uses a 320 filter. And yes, it's yellow.

And it worked...

Not exactly the old school look, either.

t

post-16741-13667651962524_thumb.jpg

post-16741-13667651964562_thumb.jpg

"I learn best through painful, expensive experience, so I feel like I've gotten my money's worth." MattL

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