I thought one comment from Rick was interesting. Mike Davis and I both
thought that my block was cast due to the rough surface where it was pulled
out of a mold. Yet I was always under the impression that Rodec blocks were
forged. If what Rick says is true, apparently it is cast first, then
"forged" (pressure and heat) which would explain why my block and my heads
don't have pinholes or voids anywhere, yet they have rough casting mold
release areas that make it look like it was a casting.
Mike Kimball
SR #044
-----Original Message-----
From:
mike.davis@dcsol.com [mailto:
mike.davis@dcsol.com]On Behalf Of
rickhm@mindspring.com
Sent: Friday, August 22, 2003 10:09 AM
To:
murphy-rebel@dcsol.com
Subject: Re: RE: PSRU Adapter
Mike,
I checked this AM with one of our Mechanical Engineers. He is also a car
racer and rebuilds his engine about every 20 hours because they are run so
hard.
I was close. There is actually very strong grain in billets. The process
of rolling and forging creates a very dense strong structure. At times the
grain in the billet will be use to the advantage of the part design for
strength. Castings can be just as strong, but require more metal. When
they make a crankcase they first cast it and then forge it by heating and
applying extensive pressure. In the case of an engine block they will get
it red hot and then somehow pound on it to "forge" the metal. I shared your
observations about your PSRU casting. He agreed that the pockets and
bubbles are cause for concern. The key question is does the casting have
the same or more metal as its predecessor part that was cut from a billet.
Hope this helps.
Rick
-------Original Message-------
From: Rickhm at home <
Rickhm@mindspring.com>
Sent: 08/21/03 06:31 PM
To:
murphy-rebel@dcsol.com
Subject: RE: PSRU Adapter
Mike,
I design medical equipment for a living. As such we rarely run into the
forces that an engine go through, but if we need a strong part we cut it
out of a billet. With casted parts there is a "grain" that is formed by
the flow of the aluminum. BIllet stock typically is viewed as not having
a
grain. I'm sure it does, but there isn't a sense of grain due to the
issues that Bill mentioned, i.e. rolling etc. I would make a phone call
and ask them how many of the cast parts are operational in the field and
what their history is! As I have looked for my PSRU I have tried to avoid
both welding and castings. Bill does make a good point that many parts
are
made from castings and I have seen good strong castings made. But given
the forces involved I think you need to ask more quesitons, to be sure!
Hope it works out, surprises are never fun!
Rick
-----Original Message-----
From: Bill Delcambre [SMTP:
bdelcambre@cox-internet.com]
Sent: Thursday, August 21, 2003 3:32 PM
To:
murphy-rebel@dcsol.com
Subject: Re: PSRU Adapter
Well Mike,
Not being an engineer or metalurgist, I'll give you my opinion, as
developed from too many years of dealing with welding of aluminum.
Billets
are the result of rolled or forged ingots. The material is dense and
clear
as a result of the mechanical working that makes it a billet. Voids or
pinholes would be extraordinarily rare. Castings are produced by pouring
the molten metal into molds and then final machined from the result. Not
only are castings inherently porous, as a result of trapped gases during
the
cooling process (pinholes) but the alloys used for casting are not quite
the
same as those from which the billets are produced. In welding, you'd be
amazed how porous aluminum castings are, even really good ones. Aircraft
cylinder heads, for example, are castings. They're good ones, but have
more
porosity than you'd imagine. Doesn't seem to be a problem. If it's
machined from billet aluminum, you won't see any voids or pinholes. If
it's
a casting, what you've described is not surprising, to me. There's a lot
more differences between castings and billet items, as I'm certain will be
described by those more knowledgable than me, but bottom line is your
confidence in the manufacturer. As stated, cylinder heads are castings
and
work just fine. Properly designed, nothing at all wrong with a good
casting.
Bill Delcambre
I received my PSRU to engine adapter yesterday. I am disappointed in
the
quality of the casting. On one side there is a large void, like a
little
cave in the casting. And there are pinholes everywhere which may be
permeated throughout the casting internally where I can't see it.
Indeed,
there could be large voids similar to the one I can see. Another sharp
angled void is present on one of the edges that would certainly be a
stress
riser. I was also surprised it was cast. I expected a machined part.
The
website says that the gear case is machined from 6061-T6 billet stock.
I
assumed the adapter would be too. Is it possible it was and the voids
were
present in the billet? I don't know anything about how billet stock is
created.
Mike Kimball
SR
#044
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