RE: Boost controllers: A very positive data point (10v turbo)

["Sherry & Chuck Clark" <clark@rmi.net>]

Geoff,
    Excellent post concerning the boost controllers. I was at Steamboat
again this weekend, this time with the NW quattro club so I couldn't
write of my experience to the list with the Greddy Profec B boost 
controller in my modified 10v turbo motor. 

Let me first clarify a few things regarding my decision for the boost 
controller. With any of the modified computers that I have run before
(TAP, IA, Home brew) I was consistently getting boost spikes which,
depending on outside temps, would cause pinging(pre detonation) at 
anything above 15psi boost. Without a trained ear, the ping was barely
audible, but if you didn't get your right foot out of it pretty quick like,
you "may" be counting the seconds before you're looking at a rebuild.
I was also running a massive wastegate spring to get quicker spoolup.
This made me feel uncomfortable and since I have just had my motor
rebuilt for the second time in 5000 miles, I wanted a few safeguards
to prolong the longevity/reliability of the new motor, hence my decision.

A few of the mods to the new motor include: Rebuild from the 
bottom up including a modified baffled S4 oil pan, 200q flywheel, 
adjustable cam gear, 268* camshaft, port and polish head and matched
port intake manifold, Dialynx exhaust manifold-already larger ports,
fuel mods, k-24 turbo, bypass valve setup, cone filter conversion,
2 5/8" Stromung exhaust(similar to Scorpion) and no cat. This all entailed
quite a bit of readjustment of the fuel system but once we got it, the car
runs really well. 

Just as Geoff stated, my Greddy Profec B spec replaces the wastegate
frequency valve with a much quicker actuator that must be mounted
somewhere cool. Yeah right, find me a cool place in any Audi turbo bay.
So we went with a mount below the black plenum that covers the heater
box and some A/C components. I mounted the boost controller itself 
just to the left of the steering wheel and right above your left knee. It
has four main knobs which include a low boost, high boost, balance and
select knob. The balance knob was the only one that took some playing
with to get it right but I still don't know if it makes a whole lot of 
difference. Anyway, what this controller does is eliminates the oem WGFV
and pulls boost only from the bottom of the wastegate itself now. The
boost response is much quicker(also due to the k-24) and is dead
consistent with your pre-set boost limits. I can now pull 8-10 psi in third
gear at 2000rpms and rapidly see 16 psi by 3100rpms. Another plus is 
the boost attainable in 1st and 2nd gear. The pull is downright fun off the
line now where in the past, I had to really rev the motor to get any kind
of jump. So I too feel that the boost comes on sooner, feels stronger and 
stays much more consistent at the limit. Not having to lift your right
foot and then get back on the gas once ping occurs is very nice. 

I've now set my high boost at 19psi which most of the time works well
with no ping except on warm/hot days. If this occurs, I just dial it back 
to 15-16 psi. The low boost is set at 10 psi. The balance knob has what 
is labeled a "mild" and a "sharp" side. I have left the knob in the middle
or balanced between these two areas. It is supposed to be adjusted
to the mild side when unstable or hunching boost occurs also known
as falling off. The sharp side is for when over-boosting occurs. Turn
the knob toward the mild side if over-boosting does occur. I have 
found that the middle selector works best for my application.

Bottom line, I think it's a very cost effective mod for my peace of mind.
Just thought I'd write of my experience with this boost controller. HTH,

Chad Clark '87 5k Tq
Colorado Springs, CO