what is a shrapnel knob?

[Robert Mangas]

   I'll let someone with more experience in that setup answer the safety 
question, but keeping the 'gate closed until (or nearly until) your boost 
setpoint will feel a lot different than one that sees boost pressure all the 
time.  The first car I made such a modification to was a turbo Talon that I 
had.  It made the boost rise-rate much faster, and increased the 'brutality' 
of the sensation of coming on to boost.  Pretty much the same thing in my 
turbo Miata- if you set the ecu in such a way that it exerts no control over 
boost it runs on the wastegate actuator only.  It's a really creamy 
sensation of power, very gentle in its onset and easier to drive.  Change 
the ecu settings to keep the solenoid valve closed so that there's no 
pressure in the actuator until the setpoint is nearly achieved and it both 
feels stronger and more abrupt.  I like it both ways- just driving around 
I'll have the 'boost assist' function engaged, but it's easier to drive on 
the track with it off.

$0.02,
Robert

>From: CL Wong <montesawong at yahoo.com>
>To: Brett Dikeman <brett at cloud9.net>, AudiFans <quattro at audifans.com>
>Subject: Re: what is a shrapnel knob?
>Date: Sat, 6 Dec 2003 09:40:04 -0800 (PST)
>
>Brett, your warnings on the shrapnel knob is noted,
>but I'd still like to explore the
>advantages/disadvantages of that other valve in the
>link.
>
>How would reducing wastegate creep on my chipped 3b
>feel?  and is it safe?
>
>
>thanks all!
>
>Chi
>--- Brett Dikeman <brett at cloud9.net> wrote:
> > At 7:54 AM -0800 12/6/03, CL Wong wrote:
> > >Yes, I've checked the archives.  Lots of folks have
> > >them but haven't found any references on how to
> > build
> > >one and what it does.
> >
> > It just progressively restricts how much the
> > wastegate can close.
> >
> > It's also incredibly stupid, considering that you
> > can neither hear
> > pinging until it gets engine-damaging bad, nor react
> > fast enough once
> > you do.
> >
> > >Looks interesting and I'd like to try building one
> > for
> > >my 20020v for kicks.
> >
> > Extremely stupid idea.  If you don't blow the
> > engine, you'll overspin
> > the turbo- get a chip instead.
> >
> > Brett
> > --
> > ----
> > "They that give up essential liberty to obtain
> > temporary
> > safety deserve neither liberty nor safety." - Ben
> > Franklin
> > http://www.users.cloud9.net/~brett/
>
>
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