manual boost controllers, and ECU functions

[isham-research.freeserve.co.uk at pop.pol.net.uk]

> Disagree.  A really _noticeable_ change requires a boost controller.  The
> scope in the systems without the spring is the same.  The problem is that the
> WGFV can't add enough boost fast enough to overcome initial wastegate
> cracking.  This is what gives midrange torque.  A failure of the design of
> the WGFV, *not* the wastegate or the spring in it.

Oh, I don't know.  I found the difference between 1.35 bar and 1.85 bar
on my MC-2 with Scott Mockry's spring and chip pretty 'noticeable'.
Audi's stock claim is 165 bhp - I reckon I'm now between 220 and 230
bhp.

> Basic misunderstanding of boost, and how it works.

Tsk - there we go - my basic misunderstanding of all things technical
again.

> A WGFV is designed to ADD boost pressure on top of baseline WG spring
> pressure given Charge Air temp, WOT, Atmospheric pressure, water temp and
> knock inputs.

Actually the MAC11/12D/14 WGFV is connected to both 'vacuum' and 'boost'
inputs and uses both to modify the effort exerted by the spring.  Its
major functions (at least according to Audi) are to reduce turbo lag and
facilitate achieving the design power output with some precision - this
is an issue with the TueV in Germany and purely mechanical solutions
such as those used in the WR were no longer acceptable.

> It's major function is to provide a safety net ...

It has nothing like the scope of operation.  Disconnect the middle chamber
hose on a 10V and see how much control it has - you'll go straight to
fuel pump cutoff.

It's true you don't necessarily need a wastegate spring change on the
newer cars.  The S2 Avant I'm currently working on was lifted to ca.
285 bhp by software alone.  I've never noticed that the WGFV on these
cars is particularly prone to failure - I've had three failures on
MAC12D cars, but I've never seen one on a Motronic car.

--
 Phil Payne
 http://www.isham-research.freeserve.co.uk/quattro
 Phone +44 7785 302803   Fax: +44 7785 309674