E 24 exhaust comments (long)

["Kevin & Dianne Miller" <knmlr@xxxxxxxxxxxxxxxx>]

Mike Chadwick wrote the digest looking for comments on E 24 exhaust/fuel
pump.

This project sounds too cool!
Personally, I'd go with MM set up for
what it includes.  I've read his "book" over
and over, and I like his thoughts on the 
exhaust.  But I realize that BMW put
a lot of research into building a system for
our cars. You can see it in the details, like
aluminized heat retention shielding surrounding
the downpipes and cat. which is protecting
a fiberglass type of insulation underneath it.
It's because of that BMW thoroughness that
Dinan doesn't mess with the front (too expensive),
and only reworks the original muffler to get his
results.  Still a lot of money for his effort, plus
it'll rust thru in time like the original!

To achieve the same results as BMW with the
heat retention in the downpipes, plus ensure longer
life and a cleaner look, I'd have them ceramic coated in and
out.  A company called HPC (no affiliation) coated my valve cover
and thermostat cooling assembly with great results, while
Jet Coating (no aff) did my MM ported manifolds.  The MM manifold
were done in 92-93' and holding up well.

But it's this company, HPC, that has a high temperature coating,
1800+ degrees, for special applications.  Developed for it's heat
retention, better thermal gas flow, and cooler engine bay, for professional
racing.  Not too much more than regular coatings, but it only 
comes in the color medium dark blue.  This is the way I'm going.
Coat the inside and outsides of the pipes.  If they will do the outside
of the separate cat, I'll include that too.  From the cat back 
I've always thermowrapped them up to the muffler after first sand
blasting the metal for better thermal paint retention. But the wrap
over time (3-4 years) becomes fragile to the touch if not occassionally
repainted.  This is time consuming and a pain to do. 

Jim Rowe, at Metric Mechanic, remarks in his selling points about
the MM300, that it's design lessens the chance of moisture condensation.
This ensures a longer life in the product.  So with that thought in mind,
I'm going
to have the muffler coated as well, but not in the blue thermal coating.
>From cat back I'd use regular thermal coatings.
Cost?  Hight Temp Coating for exhaust pipe: $12 per foot in&outside
Muffler: $25-50,  Reducers: $12 ea.
Extreme High Temp Exhaust  Component coating (1800+ degrees), I believe
is $30 per foot for pipes.

The coatings plus MM 300 is still cheaper than any other alternative for a
whole system.   HPC's number 1-800-456-4721 (Mt time)

Kevin 
86 and 88 535i

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