I'm trying to sort out a heater of sorts on a car that's no longer got the standard heat exchangers, and need to make up some ducting.
For the straightish bits I'll stick with the standard insulated cardboard tubes, they're good for sound deadening, but I also need some tight bends in places, so I'm looking for something like the bends used in plastic drain pipe. They need to be 2 3/4 - 3" around 70mm. I've hunted around a bit, but so far not found anything.
My only other idea is to make something up out of fiberglass which is quite a lot of work, so I'm hoping someone knows of something else that may work.

Try here
http://www.autosiliconehoses.com/silico ... cting.html

Agreed that stuff is excellent.

That stuff does bend quite tight doesn't it? And you did find it was OK for noise didn't you Sam? Something rigid might be better as it would be more self-supporting, and also I'd like a junction where one pipe splits into two. I'm sure rigid silicon pipe is available in 3", as would be stainless steel, both being used in induction pipes. But theyre both quite expensive so I was wondering if there was something like domestic vent pipes used for bathroom and kitchen extractors, but they all seem to be 4" and up.
I may come back to the first suggestion if I find nothing else.

It's ok noise wise i think, you only really hear the noise on de-mist

Joolz,
I use these all the time, 2 of them plus a shorter section of the original carboard tube for the driver's side demist run...
Just need a couple of notches cut into them for a better fit onto the bulkhead stub.

http://www.screwfix.com/p/92-5-offset-b ... 68mm/53298

Ah yes gutter down pipes, why did I think they were the wrong size??

Are the couple of notches to fit them over the seems, have you got a picture of them in situe? Do they glue together with that polystyrene cement used for waste pipes? I'm wondering if I could cut them and join them together to make a junction.

Aha! Sorry, should be thinking for myself.

I'll go outside in the morning and check the measurements of the ones on the side of the house.

Ha!
See you've already stumbled across the 2 into 1 connection.
That glue is serious stuff, not to be sniffed at...

take care with the exhaust heat. Many 2cv's have burned down by tubes (al kinds) falling on the hot exhaust. I bought a burned german one for 250 DMarks once. I could revive it.