[s-cars] Bypass valve thoughts. . .? Random Materials thoughts

[Trevor Frank]

I always thought that aluminum was a bad choice for a cylinder head and
cylinder case/cylinder bores.  Because of it's high thermal conductivity
the efficiency of the motor is very limited, it's high thermal expansion
can play havoc also.  Cast iron or better yet ceramic's seem to be a
better choice.  Coating an aluminum head with ceramics as long as you
have a cast iron block may be a second choice, I have and I know others
on the list have experimented with this on head's and piston's even
exhaust ports.  I remember years ago some company was selling a nearly
all ceramic motor, in passing I wonder what ever happened to the move to
more ceramic parts in motors.

-----Original Message-----
From: Ned Ritchie [mailto:Q at IntendedAcceleration.com]
Sent: Wednesday, October 01, 2003 10:56 PM
To: S-Car-List at audifans.com
Subject: RE: [s-cars] Bypass valve thoughts. . .?

Lehmann's response was simply:
"The boost is too low"
============

Yes, I thought about that too.  What did he mean?

Well upon examination and investigation here is further info:

   These engines use the all aluminum block.
   High boost will create too much heat for the aluminum.
      Ruf's modified aluminum engines are limited to 17 psig.
   Boost was also limited to 17 psig in this Audi engine,
   BUT the turbo was sized for Volume at that pressure

   Now the intercooler was a bathtub in size, and if the pressure in the
intercooler was all bled away at each shift it would all have to be
pressurized again before power would be reestablished.  I speculate that
the pressure spike could be absorbed by the gigantic intercooler too.

Ned


-----Original Message-----
From: Mihnea Cotet [mailto:mik at info.fundp.ac.be]
Sent: Wednesday, September 24, 2003 2:45 AM
To: Ned Ritchie; S-Car-List at audifans.com
Subject: Re: [s-cars] Bypass valve thoughts. . .?

Huh? I'm sure curious to hear Herr Lehmann's reasons for that, though he

must know better than ***ANY*** of us here...

Mihnea, kneeling for Heinz Lehmann and Peter Link :-D

At 02:26 24/09/2003 -0700, Ned Ritchie wrote:
>Over the years Heinz Lehmann built several 450 to 530 hp engines for
>Frank Beddor's Sport quattros in Minnesota.  On these engines he also
>REMOVED and blanked off the Sport quattro bypass valve.
>
>WHY?
>
>This is something to banter about on the list for awhile before I give
>Heinz Lehmann's reason.
>
>Ned
>
>--
>
>
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