Re: DIS for GMECM

["Bruce Plecan" <nacelp@bright.net>]

Mastercraft Ski Boats?.
You know of an on line series of photos maybe?.
Bass Boats are all I see around here.
Bruce



> 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@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@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@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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