[TECH] Cis to CIS w/ Knock Box

[Dan Bubb" <jdbubb@ix.netcom.com (Dan Bubb)]

The knock sensor ignition is simply insurance.
Discounting the accuracy of either system (and the mechanical advance system
is bound to be less accurate!) both can be timed to provide the spark at the
optimum advance for maximum power. Note that the ignition advance for
maximum power is not necessarily at the point just short of ping or
detonation. If you use crummy gas you may want as much advance as you can
get, but if you're running premium the knock threshold should be high enough
that the maximum advance that could be run just short of ping or detonation
would be too advanced for maximum power.
Noting that there is nothing inherently wrong with the advance curve
provided by the knock sensor ignition there is no downside or loss in power
from installing it. But, the knock retard is there to protect your engine
should you run into conditions promoting knock such as low octane gas or
very high ambient temps such as Patrick may run into in Texas ("85'F with
88% humidity... all week...".)
On another subject, the absense of vacuum advance does nothing to increase
your power since there is no vacuum advance at WOT.
Not having vacuum advance hooked up WILL hurt your mileage. Under part
throttle or cruise conditions the air/fuel mixture in the combustion chamber
burns slower than a fully packed combustion chamber so needs more advanced
ignition for maximum efficiency. Without vacuum advance at part throttle
conditions the fire is being lit too late and less force is exerted on the
piston over the duration of the power stroke.
Disconnecting vacuum advance was something racers used to do back in the
'60s since there is no need for it in a race car, but not having it in a
street driven car is a waste of gas.
It is good to see you're currently running max advance of 32 deg. IIRC you
used to run 37 which is too advanced for maximum power. (at least according
to Techtonics and NGP racing.....)
just my .02
Dan


----- Original Message -----
From: "Decker" <boisfort@myhome.net>
To: "_Scirocco Mailing List" <scirocco-l@scirocco.org>
Sent: Tuesday, May 06, 2003 1:49 PM
Subject: Re: [TECH] Cis to CIS w/ Knock Box


> Hi Patrick;
>     Unless you are running some ungodly high compression ratio why install
> the knock box.? By definition it is there to retard ignition advance and
so
> to rob power. In my 79 Scirocco I'm running an Audi 1800 8V with 10 to 1
> compression, no knock sensor and it is truly happy with premium gas.
Tuning
> specs are distributor with points, only mechanical advance ( no vacuum
> advance or retard ). Timing is set to 32 degrees total advance.
> Brian Decker
> ----- Original Message -----
> From: "ATS - Patrick Bureau" <txrocco@sbcglobal.net>
> To: "_Scirocco Mailing List" <scirocco-l@scirocco.org>
> Sent: Tuesday, May 06, 2003 10:15 AM
> Subject: [TECH] Cis to CIS w/ Knock Box
>
>
> > Dumb question I am sure but just want to make sure of what I am wiring.
> >
> > I understand the diagram to install the knock box, but what I need
> > confirmation on is the following
> >
> > For example, the current CIS system has ignition wire running (all 3)
from
> > Hall sender to Ignition Module, the diagram indicates to wire the 3 hall
> > sender wires to the knock box, do I TAP into the lines or I remove the
> lines
> > from the ignition module and run them to the knock box.
> >
> > I am pretty sure I am supposed to "relocate them" but just wanted to
make
> > sure. Thank you for the confirmation on this issue.
> >
> > PS: damn its hot in Dallas.. 85'F with 88% humidity... all week...
> >
> > ATS - Patrick Bureau - txrocco@sbcglobal.net
> >
> >
> > _______________________________________________
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>
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