boost guage and zener diode questions...

[Ben Swann]

My advice - don't be cheap and end up paying more later.  The chipset I have
for this car allows you to safely operate at 2+ Bar of boost.  It is a
relatively new chip, available only since January, 2006.  In the long run you
will be thankful you didn't install a $1 resistor and risk detonation and lean
condition that can ruin your engine.

Ben

DIY performance mods: http://www.homestead.com/ben_swann/gtqkits.html

-----Original Message-----
From: tmb [mailto:the_questionist at yahoo.com] 
Sent: Wednesday, July 12, 2006 10:33 AM
To: Ben Swann; audifans
Subject: Re: boost guage and zener diode questions...

> Which vehicle are we referring to?

1989 audi 200TQA with a dual KS setup and the MAC-14 ECU.

> Why do a Z/R mod when the chips are offered at reasonable price.

cuz it can't possibly be more reasonable than <$5 worth of resistors.  please
insert correction here if i'm wrong.

> The Z/R mod will definitely skew the digital  boost readout and not reflect
actual pressure. 

> Resistor will skew the readout to display less than actual.

that's alright.  with the new fancy schmancy guage installed, i'll be staring
at that instead of the original unit.

> Zener will clamp the output of the PT so the readout will max out to a
particular value regardless of peak.

i can deal with that assuming that the WG spring is the right rate.  i friend
of mine ran an indicated 2.2BAR on his 5000TQ for 250Kkm with no issues.  that
kind of experience is enough to convince me.

> Also  the digital readout is not necessarily  accurate even in an un-modded
> setup.  Each .1 bar is about 3 PSI and the readout can lag as boost changes.
> It is for a ballpark measure only.

ah.  good to know.  

thanks to everyone so far for their info.

jason
tmb