Hot Bolts and Galvanic Corrosion

[Phil Payne]

>> but for anything around the turbo,
>> stick with what the factory had there.  I'm not sure
>> what the studs on the EM and turbo are made out of,
>> but I haven't been able to find anything that comes
>> close to resisting corrosion like they do.

> I must agree. I have never seen any material by any manufacturer stand up to
> exhaust abuse like the Audi turbo and header hardware.
> I have often told people that ask why I like Audis, that _one_ of their
> attributes is their choice of materials for interiors, metals etc. I challenge
> anyone to find another builder whose dashes and exhaust hardware stand up to the
> elements for 20 years as well as Audi. There are probably some as good, but
> none better for my money.

Turbo to downpipe especially.  Audi's nuts are a non-standard size - they're 1mm down on the
across-flats size they should be for the thread, to make it easier to get a socket on them.
Because the walls are thus thinner, they're titanium and accordingly expensive.  But I don't
think you'll find better anywhere.

I generally avoid using stainless unless absolutely necessary.  One place is the captive bolt
on the end of the cup that holds the base of the bomb - it's very exposed to corrosion.
Another place is the union between the concertina pipe and the downpipe - those three are
always rusting up.  As far as the exhaust bolts down the pipe are concerned, I keep a box of
spares in the workshop and take the old ones off with an air hacksaw.   BRRRRT - ping!

--
  Phil Payne
  http://www.isham-research.com/quattro
  +44 7785 302 803