Date:         Fri, 26 Jul 96 10:00:11 +0200
Sender:       Vanagon Mailing List <vanagon@vanagon.com>
From:         verbeek@the-hague.stbv.slb.com (brian verbeek)
Subject:      Re: vanagon headers

Colin said:

<<I've been thinking about making a set of headers for the 2.1.  I have
already made a muffler using a straight through glass pack.  I was unwilling
to spend over $100.00 on a new OEM type muffler.  Is there anyone who has
experience in header fabrication, or know of someone who builds headers.  I
would like so ideas and pointers before I try it.  Books tell alot, but
experienced insight would be invaluable.  TIA>>

2.1 WB, why shouldn't a high performance T1 or T3 exhaust system fit?
The Germans use them, especially when its mounted in a Bug, i recall
that the flanges are rotated compared to the regular T1 and T3, but
that easy to overcome, especially if you buy a system that has 'loose'
flanges. Another nice thing is that you don't have to give up the heater, in
an aircooled you have to to get rid of the too small dimensioned heaterboxes.
(when using larger than stock valves only)

If you are determined to build your own, you'd have to: calculate/test
correct header lenght, make sure they are all exactly the same lenght, that 
the bends are as smooth as possible, that the bends remain the same
dia after bending them into shape, collector shape and lenght etc., that
if you want to go from 2 x 2in1 and then these two into one you join 1 and 3
and 2 and 4 before these combinations join together, adjust the tube dia
to the exhaust valve dia. i'm sure other people can come up with other
things to consider, make sure that your exhaust system flows at least
the same as stock, if not, it will reduce volumetric efficiency, ie
the exhaust gasses won't exit the cylinder properly and/or fast enough,
obstructing the incoming gasmixture and driving the headtemps up, the
temps rise because the burnt gases are longer around to heat things up
and because the burnt gasses dillute (lean out) the incoming unburnt mixture
that's why some German HP exhaust system manufacturers claim (and prove) lower
operating temperatures when using their systems. Too thick tubes will reduce
velocity of the exiting gasses, reducing the 'extracting power'.

I'm not an expert on the subject, just my 0.02 guilders worth...

Brian.