Digital Distributorless ignition q's

[Matthew B. Watts]

-----Original Message-----
From: Marc van der Vossen <marc at vdvossen.cistron.nl>
To: DIY_EFI at efi332.eng.ohio-state.edu <DIY_EFI at efi332.eng.ohio-state.edu>
Date: Monday, March 02, 1998 8:58 AM
Subject: Digital Distributorless ignition q's


>Hi guys.
>
>I'm planning on building a ddi for a chevy V-8. My questions are:
>
>1. could i make a cranktrigger using a wheel with 4 holes where the light
>can come through (light sensor input) and make one hole the double length
to
>see where no.1 cylinder hangs out. I think with a light-based system you
>won't have much noise in your signal and the output is very consistent. Any
>input ?


The Mallory UniLite ignition system is optical and works quite well
from what I've seen.  I would certainly attempt to shield my optics
from the environment as much as possible though.  At least make
the mounts quick-change so that they can be checked and cleaned
if necessary.  Most sensors are IR which makes it a little tough to
observe with the eye.  During your prototype phase, I'd look into
getting some visible light sensors and work with the gain settings
to make things functional.  It's awefully hard to fix what you can't
see (my primary gripe with Hall Effect sensors).

For the #1 cylinder, I'd use a seperate hole and signal feed.  I'm
not sure if that's what you meant or not.  If you just modify the
primary signal by widening the hole, then you'll be up against
determining when this "different signal" occurs.  I'd keep it all
digital if you're into drilling holes anyway.  No sense in making
the project any harder than it need be.

>2. Which coilpack should I go for ? I won't need more power then a stock
HEI
>coil, because the engine is not laughing and not blown (super or turbo).


I'd use Mallory because I know they work.  I honestly think that
you could pick whatever is available to get you started and then
maybe experiment once it's all running.  Try a few different ones
and see if horsepower and driveability changes any.

Good luck and let us know how it goes...

Matt Watts
University of Utah
Formula SAE Racing
__________________