[Diy_efi] boosted compression ratio

[Mike]

Ah ha, I see

Clearly they are time correlating the 'window'(1) of ignition for a
specific cylinder with the detection of knock. Althought they
might like us to think its a 'complex algorithm' - I really dont
think so - I could draft it in a few sentences if anyone's interested.

I wonder though what the upper limit on revs is as a great deal of
engine rattle can appear as ping about 4000 rpm or so (The ECU for
my GMH with nissan RB30ET has an upper limit too, around 3000rpm
*and* all it does is retard the timing by 5deg - sob sob). I'm
guessing that one could go for more sensors, use a DSP and filter
out a great deal of other engine noise to have usable knock
detection up to rev limit...

Rgds

mike
(1) Period of time during which there is a high probability
of occurence of knock


At 11:20 PM 21/12/2002 -0600, you wrote:
>
>> Interesting, ? Can you elaborate on your knock sensor relationship to
>> which individual cylinder retard is managed - or do I infer you have
>> multiple knock sensors...
>
>It's made by J&S Electronics, called the SafeGuard. It only uses one
>sensor.
>
>> ie. If you have one knock sensor - how do you know which cylinder
>> to retard by how much - especially at higher rpms, is there a low
>> rpm cutoff for this algorithm ?
>
>I'm not exactly sure the processes it uses, but it is proprietary and
>supposedly a very complex algorithm. It is disabled at under 1500 RPM as
>you expect. The display shows which cylinder it is retarding, and by how
>many degress. It can pull up to 20 degrees per cylinder. Their webpage:
>http://www.jandssafeguard.com/tech.html
>
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