Manual boost controllers

[Trevor Topley]

Hi everyone,
                    in my response to turbo whine and the increased
noise I have after removing the silencer before the IC, I mentioned my
manual boost controller and bypass valve on my 90 200q. I believe it was
follow up to this that has started this thread.
There seems to be some confusion between a manual controller(Hallman,
Redline etc) versus electronic control(Apexi, HKS, Audi wgfv etc).
Phil I think it was said about seeing what happens when you feed 100%
manifold pressure to the top chamber of the wg!!
Exactly the same if you remove or clamp the hose to the lower chamber.
Nothing relieves the exhaust flow to the tubo and boost builds very
fast!
Now put an adjustable spring loaded ball bearing in the line to the
lower wg chamber, preset it so that it lifts off of its seat at say
1.5bar, because the hose is small and short there is little volume.
The pressure almost instantaneously goes to 1.5b at the wg and it opens
- bang.
There is no pressure at the wg until the preset level is reached, so
wastegate cracking is no longer an issue.
Boost drops, the spring loaded ball reseats.
Boost rises again because there is a small bleed orifice in the line
between the spring loaded ball and the waste gate, which relieves the
pressure in the lower chamber allowing the wg to close.
This is how the "ball and spring" manual controllers work.
1.5b will be there by 2000rpm accelerating at part throttle.
Cruising at say 2500rpm, there is NO lag, touch the go pedal and it's
1.5b!
It absolutely transforms the character of the car.
Without the bypass valve it was very difficult to drive smoothly!
Mine is a Hallman, purchased gadget for $55, but just a selection of
brass fittings and some minor mods.
Total cost with the bypass $200Cdn.
I have been running upto 2bar for a year now(12,000 miles on a
115,000mile car, with no sign of it retarding, knocking or blowing up
yet. It is pretty flat around here so the motor is never under load for
extended periods.
I have pulled plugs several times and they look good, exhaust tail pipe
is black.
Gas mileage is good too, 30mpg on long runs.
Getting high boost without having to go to WOT is very nice, really
feels like a V8.
Obviously I am happy with it, and would do it again.
Risks, certainly, I have an above average "feel" for the way a motor is
running and would not reccomend this set up for any one who hasn't any.
I never did find a reason why my maximum boost sometimes drops to 1.7b,
and falls to 1.4 in 3rd gear at high load/rpm. Since it fixes itself, so
far, I'm still thinking the problem could be internal in the wg.
Any other ideas?
Trevor Topley
90 200q.