Intake Runner Length

[Van Setten, Tim (AZ75)]

> >> What for ecm?.
> > We ended up conjuring our own.  (Mainly by swiping circuits out of
> >every known ecm in the free world).  We wanted a box with knobs on it
> that
> >controls the basic fuel curve.  It's not a good idea to take a lap top
> out
> >into the sand dunes to change the fuel curve.
> 
> 
> Care to give any details about the ecm?.
> 
	The ecm started out using a 68HC11, but to make a very long story
short, we ended up making an analog system.  The digital stuff is a
nightmare.  You have to remember that this IS the most electrically noisy
environment around.  Magnesium engines, steel frames, aluminum do-dads, high
RF fields from radios, lots of emi from magneto's, (to really screw up a
ecm, watch what a MSD 7AL2 multi-spark does using solid core wires), but the
topper is when some of these village-idiots use a garden tractor battery to
try starting a 13:1 compression motor!
	Yes it can be done, and when we did this years ago, we were heading
for a box the size of a coffin to buffer, hold-up, condition, isolate, the
signals.  The killer was using methanol and trying to convince the O2 sensor
to stay alive.  When we went to a basic analog system, 99.99999% of the
problems went away. (No processor resets, endless loops, watch-dog timers,
etc..etc..).  
	Going to a speed-density system, (TPS and Tach), sequential-double
fire, we could use pot to trim overall curve, idle, mid, top end.  Adding a
MAP gave us the additional curve for the boost correction fuel.  I can't go
into schematics without giving up too many secrets, but I'll try to answer
questions.  (Hope I answered some of your questions Bruce).
	Tim.