AS21 sure sounds like a Mag Alloy to me. I'm mostly familiar with die
casting alloys. They currently use an AS41B for die casting.

Composition is similar at:
3.5-5% Al
.12% Zn
.35-.7% Mn
.5-1.5% Si
.0035% Fe
.02% Cu
.002% Ni
.02% Other
Balance Mg

This alloy is perhaps very close to the one mentioned. These alloys are very
susceptible to cold defects but are generally easy to work with. The major
benefits I see in using such an alloy is holding pressure, resistance to
cracking when hot because elevated temps don't seem to change the strength
much.

As far as BMW goes, I've looked at a lot of 40's and 50's Beemer's and all
the V8's have Al blocks and heads. Yes, 3.2L V8's. They are what gave the
Beemer the nickname "Whispering Bomb".

That's my bit.

-Steven Dodson
Kneeland, CA
"Inga" the 87 Syncro

-----Original Message-----
From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com]On Behalf
Of Stan Wilder
Sent: Thursday, August 29, 2002 9:00 PM
To: vanagon@GERRY.VANAGON.COM
Subject: Re: Fire Extinguishers

We don't run around with that rough part of the VW crowd, we stick with
the conservative Pacific North West group.

Stan

On Thu, 29 Aug 2002 21:29:58 -0600 Ben McCafferty <ben@KBMC.NET> writes:
> Come on, you guys!  Haven't you ever been to a good old fashioned
> VW-engine-case-bonfire???  No, I'm not kidding.  Quite
> spectacular.....
> bmc  :)
> "Faith will move mountains, but you'd better bring a shovel...."
>
>
> > From: Jim Arnott <jrasite@EONI.COM>
> > Organization: http://WetWesties.org
> > Reply-To: Jim Arnott <jrasite@EONI.COM>
> > Date: Thu, 29 Aug 2002 20:09:40 -0700
> > To: vanagon@GERRY.VANAGON.COM
> > Subject: Re: Fire Extinguishers
> >
> > Doing about 2 minutes of research reveals the following:
> >
> > Early aircooled engines (25 & 36-40 hp) used AS41 alloy for the
> cases.
> > AS41 is: aluminum 4.2% silicon 1%. The remainder is... magnesium
> >
> > Later 1300-1600 motors used AS21 alloy.  AS21 is:
> > 2.3% aluminum, 1% silicon a bit of zinc and manganese and, you
> guessed
> > it. Magnesium.
> >
> > <http://www.northerndiecast.com/mcalloy.htm>
> >
> > The type IV and wasserboxer case material seem to be a bit more of
> a
> > secret. But if someone can come up with the spec, the composition
> is
> > just a minute away.
> >
> > There's also a bit of info on the type2.com website.
> >
> > Jim
> >
>

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