Re: Some Boost Controller Info

[quk@isham-research.demon.co.uk (Phil Payne)]

In message <8299d6e0.36198138@aol.com> CM1022@aol.com writes:

> The Greddy, HKS, SARD, Apexi, Blitz, etc. are all pretty much the same.  They
> provide a more active control over the wastegate, but because of their
> electronic nature I don't know if it will work with an Ur Q.  Did the Ur-Q
> have an electronic timing valve?  This valve, found on most later models of
> turbo kraut cars, is a simple device the modulates between either positive
> (boost) or negative (vacuum) pressure on top of the wastegate to more actively
> control it.  This is esentially how an electronic controller wires- right into
> the electronic timing valve.  I have seen pictures of the wastegate on the Ur,
> and it seems that maybe it is just spring activated?

On the US-specification cars, yes.  On the MB (like mine) the ECU controls
a wastegate frequency valve that modulates a supply of vacuum (from the
turbo inlet) and boost (from the throttle body) to the top of the
wastegate.  This is the way the MC engine in the 5000 is also managed.

There's a subtlety that no one at Audi has been able to explain to me -
in the earlier MBs, one line goes to unthrottled air, i.e., intercooler
output.  On the later ones, it goes to throttled air, i.e., the inlet
manifold.

Anyone know why this change was made?

--
 Phil Payne
 Phone: 0385 302803   Fax: 01536 723021
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