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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