Boost Controllers

[GScruggs@monterey.nps.navy.mil]

Richard, I've been running an HKS EVC III for about a year now on my '87
5kCSq and it works quite well. I see no reason why a unit like this could
not be used on an earlier system like your urQ. 

Understand what these systems are - they manage boost by taking control of
the WG away from the ECU, but they do not replace the other functions of the
ECU.  The ECU is still responsible for ignition timing, knock control, fuel
injection functions, et al ... all of which must be in harmony with the
boost controller if your goals of increased engine performance are to be
realized. The HKS is physically connected to the engine by 12v, ground, and
three pneumatic lines.  It has no interest in how many cylinders the engine
has, it cares only about the pressures and rates of pressure increase in the
intake manifold.  I also use one of  Scott Mockry's WG springs, sorry, I
don't recall which one, he has three different rates. 
  
The characteristics of the HKS boost controller:
- It has a high-quality digital gauge, two place accuracy, to monitor both
vacuum and pressure.  (Yes, it's all pressure if you reference it to
absolute.)  This gauge is part of the control unit which mounts in the car
where you can see what is happening and make adjustments.
- You select the boost level that you want to use.  Mine has two settings,
Low, for boost below 2.0 bar (absolute), and High, for between 2.0 and 3.0
bar.  Within each setting you pre-program the exact boost that you want.
- The fuzzy logic circuitry 'learns' what boost rates are available from
your engine/turbo combination so it can hold the WG closed longer before it
signals the WGFV that it needs to begin regulating to whatever level you
have set.  Essentially, it reduces premature WG "cracking."  While in the
"learn" mode you are instructed to make three WOT runs from 1000rpm in third
gear, under identical conditions, so the system can learn the boost rates
and keep track of when and how much authority it will have to exert to
modulate the WG.  
- It comes with a much larger and more robust WGFV to more quickly respond
to controller signals and subsequently actuate the stock WG.  
- There is a function on the control unit which allows one to "tune" that
previously learned boost curve by making it more or less aggressive.   I'm
not sure why one would want to do this and have not investigated it further.
- There is an 'overboost' function which allows a preset boost increase, for
a selected number of seconds, over that which you programmed as normal. 
Kind of a 'banzai' button, I guess, if your normal settings are conservative
and the other car is pulling away from you.  
- You also get an overboost warning buzzer.  Set it where you want it.  If
you hear a "kaboom" and smell hot metal before it beeps then remember to
reset it to a lower value.

This approach to increased performance is not for everyone as it is
decidedly _not_ 'plug and play.'  There are decisions to be made,
responsibilities to be accepted and perhaps a bit of fabrication.  Decisions
like: what boost levels am I going to use, should the manifold pressure
continue to be piped to the ECU, should I seek out and maim the idiot that
wrote the installation instructions for this system.  Responsibilities like:
it is within your capability to set up boost pressures which will turn your
engine into molten slag, you must deal with the over boost fuel pump cut off
"safeguard."  Fabrication like: where am I going to mount this huge new
WGFV, making a new pressure tap for the input side of your intercooler.
Superior performance is available, but only for those to whom this level of
involvement is... pick at least one...  intriguing, challenging, or
required.

Neither does something like this answer all of one's needs.  In my case the
additional boost has made intolerable an existing problem of the engine
occasionally missing and stumbling at WOT.  It will turn out to have been
something simple but I am currently considering psychic intervention or a
trip to Lourdes. 

Marque tuners don't use these systems because they are not turnkey and
require far too much end user involvement.  If you consider what both the
HKS and the tuners do, with respect to increasing the boost, the goal is the
same just the approach is different.  Tuners sell you a complete system, the
HKS is essentially a circuit of a complete system.  When you buy the IA or
TAP modification you get a fixed performance increase that has been sorted
out, retains some safeguards, with some recourse if it breaks. Why, then,
would one go the route of an off board boost controller for increased
performance vice going to a marque tuner?  Involvement and flexibility.  It
is not for everyone.

Apologies for not responding sooner to this inquiry, I spent the weekend and
Monday, replacing the subframe bushings, engine mounts and addressing lots
of niggling problems.  I tried the lister-approved technique for replacing
the bushings without removing the subframe... didn't work for me.  But
fifteen minutes and twenty dollars at the machine shop did.  Next: new A/C
blower, new heater core, new water hoses and the Evans cooling system.

Regards, Gross Scruggs