I'm making duct work out of aluminum for track car. How thick/thin should the sheeting be. I already have 22 gauge. Is this too thin?

Ron Fournier's book on sheet metal fabrication and Carroll Smith's books on race car fabrication talk about these issues in some depth. Recommended.

Your parts are not structural - they're ducts. They need to be stiff enough to withstand 'normal' stresses and keep their shape, but if you got a small leak it's not tragic.

With flimsy sheet you 'd probably want to add some reinforcing beadwork which is an art in itself. Maybe an internal frame of aluminum 'L'-section extrusion. And probably a 'No Step' placard ...

Thinner is lighter ;-)

Or use fiberglass..........it's easy, it's comes in a can!

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22g aluminum is pretty thin. You might have a hard time working with it and making it stay in place. That being said, it can definitely be made to work. It wouldn't be my first choice to start with. I would probably get 16g so it has SOME rigidity.

That fiberglass ducting is so awesome!

on the fiberglass. That's schweet!

If I were doing more of that type of work (sheet stock) I'd pop for a bead roller.

Thanks for the responses guys. The fibeglass looks great, but it is so messy I think I'll try thicker al.

I got me some 16g today!

If it helps, this is how mine was done...