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Urq Boost/ ecu summary so far.
In a message dated 95-12-21 20:03:24 EST, Chuck Leiter wrote:
>I own an 83 qtc with a IA stage 1 or 2 (?) computer and assorted other
>goodies. My question is, how high can I go up safely on my boost. I just had
>it raised to 15 with no problems. I was running 14 before that. What is the
> upper limit and what are other people using with the stock turbo.
Trying to establish how high to let the boost go, was the original question,
that ended up turning into a discussion of ECU mods. I guess the reason was
because it probably comes down to having to answer several other questions
first. Most of the comments are related to the UrQ computer, which isn't as
smart as some of the computers in the newer cars, and knowledge and
technology have progressed since they were made and also since the early ECU
mods for them came out.
I'm guessing that some of these cars are now owned by homebrew hackers who
are really engineers of some kind in real life and want to know how things
work, and have a need to "improve" things. They probably don't own a machine
that they haven't disassembled to see how it works, so the car and it's
computer are no exception. (BTW the preceeding is not an insult, I put
myself in this category :-)) )On the other hand, many of us also use the
car for actual transportation, so how can we be somewhat secure in the
My stock '83 Urq has no problems with knock, as far as I can tell, even with
87 octane. It would seem though, that the first problem to expect as the
boost is raised, will be knock. So how do you control knock? One aspect is
ignition timing, so a lot of interest went into trying to understand what
timing changes have been made, how were they made etc. Summary: More
advance, with proper fuel gives more horses, but could lead to knock.
Knock can be detected nowadays. This wasn't available when the UrQ computers
were made. So if we are going to up the boost, there is some interest in
finding a nice knock detector to retrofit to the old UrQ's . Not only can
knock be detected, but there are knock controllers that can retard the
ignition . There apparently is an aftermarket device that can do this for us,
and is under consideration by several list members. Maybe we can do a group
Another aspect of knock control is boost control. There have been some
schemes to control the boost with wastegate mods. Instead of just a stiffer
spring , an adjustable "spring". Some computers in the newer cars control
both boost and ignition (and also fuel flow in pulse control electronic fuel
Where do we go from here?
1) I'd like to find a separate knock controller that could be adapted to the
Urq system. I suspect that after knock control was figured out, but before it
was fully integrated into the newer ECU's, a separate module may have been
made which does more or less what we need. I've seen reference to the bosch
KLR knock controller for example.
2) I've been told that a good indicator of boost trouble is exhaust gas temp.
Monitoring exhaust gas temp as an indication of cylinder temp seems like an
excellent idea to me. This could be tied into the boost controller or just a
3) The next level beyond that, could be an explosion monitor or just watch
the tach 'cause after the engine either explodes or melts it won't be moving
So how high can we go with the boost? I'm still waiting to find out. I'm sure
that there are some guidelines out there, from people who have crossed the
line under various conditions, So let's keep the ideas flowing!
'83 Urq still stock for now, but not for long.