Hydroforming - exhaust manifolds

[samo]

With Guys permission I would like you all to introduce you to an interesting and inovative technology called Hydroforming.

Up till now I have only seen this done in here in a local company that specializes in motorcycle exhausts and has only recently started doing car manifolds and silencers. (Sadly only for elite cars). Well to get to the point what facinated me the most when wisiting their factory was a process called hydroforming. What they actually do is take roughly formed pipes for manifolds and secure them in a jig then they force a water based medium at high pressure/flow to shape them as it is optimum for a fluid to pass trough.

As I think they are the only ones doing this type of pipe shaping I am posting a link to their site where you can admire the craftmanship. I think you will enjoy the site:

http://www.akrapovic.com/technology/hydroforming/

The company started as a one mans vision to make the best exhausts. So he stared making them in a shed behind his parents house...

[fingers99]

Has been used for 2 stroke motorcyle expansion chambers for a long, long time (50 years or so) but generally by competition departments and aftermarket suppliers, and of a far simpler type without a mold.

At base, do your calculations, cut two identical patterns from sheet steel (allow some sacrificial material onto which you braze/weld a union to suit a hydraulic pump, weld all round the edges. Fill pump with water, pump, and the steel will balloon. It's a nice way of forming fairly simple cone shapes, tube shapes, circles, etc. A £100 pump and a TIG welder is all that's required. Attempting it with compressed air is likely to result in serious injury.

More complex shapes either involve cut and shut or -- properly -- molds. Add the joys of TIG welding titanium and you're into a very different level indeed. `

But even at a simple level, hydroforming seems to offer some advantages over more conventional fabrication techniques. I fully intend to give it a go, someday.