Anyone made a U tube?

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#1

Hi all, Im turboing my motorbike ! I need to make a 50mm link tube from the turbo at the front of the engine to the plenum airbox at the rear of the engine behind the carbs. The tube is effectivly an elongated U…more like |________|.
I can CNC machine the outter former from MDF, seal it and use a pressure bladder to apply pressure internaly.

But what layup should i use?
I’ve thought of laying the 2 halves of the mould with fabric but the ill have a join line each side of the pipe. This also may be a weak spot under 14psi of boost pressure.
Or use the braided sleaving. Thead the pressure bladder throught it with addition reinforcement. Would the bladder be able to expand the braid to 50mm?
Or continually wrap the pressure bladder with the CF to build up 4 layers and lay in to the outer mould?

Cheers
R.

#2

14psi is minor. Do the halves and lay up a strip on your seams

#3

Yeah thought that but I dont want any visible seam lines. If any it’ll be on the engine side of the tube.

#4

I wouldn’t worry too much, Koenigsegg uses 2 part aluminium moulds with visible seam lines on both sides.

#5

You might take a look at this thread:

http://www.compositescentral.com/showthread.php?t=7007

There can be quite few cosmetic issues with putting a sleeve over a bladder. Pinholes between the weave intersections is a very common problem. The seam issue will be minor compared to the other cosmetic issues. Also the seams done correctly in a good mold can be minor. The photo is of a part right after demolding.

#6

Thats an interesting way of creating the badder. I was going to use a bike inner tube but that might not form the bends correctly. Using your way creates the shaped bladder. How much pressure do you use?
Another issue is that a sleeve may crimp up on the inside of the bends. Again if i cut the material to shape it’s already half way formed the bend.

Ok i think im set on 2 halves joined…watch this space!

#7

I use 15 to 90 psi depending on the desired fiber volume fraction and the gel time/layup time of the production.