DIS for GMECM

[Len Sabatine]

   Hey John , have heard of DIS on LT Marine  Apps , have not seen though, 
got any Pics ? . You mention OptiSpark 92-4 Spline drive , Ha , New LT1s had
   a sloppy  chain , kinda defeated the 1d res of the dist. Gm offered an O 
size crank gear as a slop fix. At any rate, the Nstar style Pkg would 
indeed eliminate
   the monkey motion for sure. While still lots of Plug wire , multiplying 
spark and dividing the load X 8 ,  Can't be wrong by any stretch. Yes, 
crank reluctor with
   Lo-Hi Res sensor positions and "usual" module sense scenario does lend 
itself to wider usage on other controllers that process like signals. 
Marine Apps ,
   not needing to do FTP certifications, can be  OEMs  spring board 
development arena for Wana Be Vehicle programs to come.
    Len

>Exactly!!  Makes me think back to the LT1 Optispark distributor.  All the 
>hoopla about 1 degree resolution with the 360 deg optical sensor, and then 
>go and hook it all together with a timing chain and a little splined drive 
>off the front of the camshaft!  Many folks are unaware of the fact that 
>when the LT1's were used in the Mastercraft ski boats, they used the 
>Northstar DIS, NOT the Optispark. The Nstar reluctor wheel mounts on the 
>back of the harmonic balancer, and a new timing chain cover is used with 
>the 2 crank sensor mounting saddles cast right into the cover. It's a neat 
>little package! The 2 crank sensors feed directly into the full-function 
>DIS module, it decodes and processes the signals, and then you have the 
>usual connection to the ECM (REF HI, REF LO, BYPASS, and EST. In the 
>marine application they used the MEFI-2 controller, but hey, it COULD have 
>been a 730/727 controller.
>
>         John
>
>
> >Date: Tue, 05 Dec 2000 18:46:42 -0500
> >From: Len Sabatine <sabatine at epix.net>
> >Subject: Re: DIS for GMECM
> >
> >
> >Think , elimination of distrib gear , rotor ,cap , carbon brush , air 
> gaps,  slop in the timing sys , ionization ,torsional vibes traveling thru cam,
> > oil pump disturbances , coil and plug wires and their routing. All 
> the >monkey motion and associated spark delivery problems , GONE, 
> especially with
> > CNP ignition sys. Spark scatter and inductive X fire tendencies , 
> GONE.  " Nearly" perfect spark delivery and repeatability is now possible .
> > Add to  that , Coil drivers are on each coil , not on PCM Motherboard. 
> A very high degree of "recovered loss" in Ignition efficiency has come to 
> pass. The
> > ms latency ,spark propagation time has also been reduced substantially.
> > Hope I've gotten the idea across.
> >     Len
> >
> >
> >>So the benefit to going w/o distributor is to prevent missed/deformed
> >>sparks?  I always figured it was to get better timing accuracy.  I sorta
> >>figured you'd get more energy jumping the spark gap with coil-per-plug (is
> >>there a industry buzzword for this?) than with systems that use
> >>conventional ignition wires.  Is this not the real reason?
> >>
> >>  On Tue, 5 Dec 2000, Bruce Plecan wrote:
> >>
> >> >
> >> >
> >> > Allz said and done, DIS will get you about a 2% less misfire rate.
> >> > Meaning thou the AF mixture was lit, the flame front for what ever 
> reasons
> >> > was unusual, and genereated less energey for that event.   Not to be
> >> > confused with a *miss*.
> >> > Coil per Plug can get you an addition 1% improvement, and get right near
> >> > 100%.
> >> > Bruce
> >> >
> >> >
> >> > > As best I understand it DIS allows a longer dwell (charge time) for a
> >> > given
> >> > > coil at higher RPM's, resulting in a hotter spark.   You also 
> eliminate
> >> > the
> >> > > wear of air gaps at the distributor caps.   Less moving parts, less
> >> > failure
> >> > > points is good from the OEM point of view.
> >> > > Also, advance is "unlimited" since you don't run into rotor phasing
> >> > issues.
> >> > >   This still confuses me, since it's my understanding that there's 
> almost
> >> > > no app that you would want more than 45 or so degrees of advance 
> anyway,
> >> > > from the tone of a lot of messages recently.
> >> > > -> Bob Valentine
> >> > > -> bob at tecmark.com
> >> >
> >> > > At 06:51 AM 12/5/2000 -0800, you wrote:
> >> > > >DIS=Distributorless Ignition System?
> >> > > >So what's the point of trying to get a "DIS" working on an AUJP/730
> >> if my
> >> > > definition of DIS is
> >> > > >wrong?  Explain to me why there is this holy-grail of getting DIS
> >> running
> >> > > on a V8/730.
> >> > > >Squash
> >> > > >--- Chipsbyal at aol.com wrote:
> >> > > >> This is not a DIS system as it is a distributor less system. 
> This is a
> >> > CNP
> >> > > >> coil near plug system. Each cylinder has its own ignition 
> module, coil
> >> > and
> >> > > >> plug wire. The interface that was at the show only drives the 
> separate
> >> > > >> modules. Speed Pro also had an interface to use this CNP 
> ignition for
> >> > > their
> >> > > >> systems.
> >> > > >> AL
> >> >
> >> >
> >> 
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