programmable engine management

["Scott F. Williams" <sfwilliams@home.com>]

Guys, I am now hell bent on rigging those individual throttlebodies and a
programmable engine management system. My goal is to develop the ultimate
(almost) all-motor 2.0l 16v for the streets and backroads. Cheapass Ron
asked me some very good questions about the engine management systems and I
responded with the following. (Maybe this could form the basis of a decent
FAQ?):

> Real (dumb) Q:  The Badger TB's have an injector port, right?
> Therefore they're for FI, right?

Yes, exactly. Although they look like a set of sidedraft carburetors they
contain no venturis, jets, or other related bits. They are essentially just
the manifolds, throttle plates, and velocity stacks. There are ports to take
the injectors as well as areas that may be tapped for vacuum, nitrous jets
(yeah, baby!), etc.

> So where does the airflow meter
> go????   Where am I stupid here?  What is my wrong assumption???

Yo, Cheapass! Your amusing incorrect assumption is that the state of the
fuel injection art is still stuck in an eighties timewarp! :^) We don't need
no steenking airflow meters anymore! Consider that the load on the engine
must be measured somehow. There are two ways of doing this: either measure
the amount of the air flowing in (our scenario), or measure the engine load
(via manifold absolute pressure) plus other related parameters.

Our barbaric air flow meter plates rise and fall on the column of air
traveling into the motor. This then mechanically actuates the release of the
(hopefully) appropriate amount of fuel. Keeping in mind that the connection
between the airflow meter and the fuel plunger is fixed mechanically, it is
difficult or impossible to make quick/accurate corrections for numerous
operating factors. Furthermore, that big plate is huge and obvious
*obstruction* to the rising air flow! It impedes the flow by the very manner
that it has to measure it.

In contrast, modern systems eliminate the air flow meter and replace it with
various mechanisms that measure the pressure inside the manifold. This
reading is then combined with the outpus of other sensors to deliver a final
fuel/ignition map. Sensors may include: air temperature, water temperature,
throttle position, oxygen sensor, knock sensor, etc.

Our systems are a relative mess of hydraulic and pneumatic hoses, cables,
and linkages. It is all a big pain in the ass to calibrate and tune. The new
style simply relies on a computer for parameter mapping, calibration, and
processing. It takes a whole new set of skills to do this, but in the long
run it is *much* more effective and is ultimately easier.

Just replacing the CIS crap with a modern engine management system can
immediately increase power, driveability, and efficiency. You can do things
like add much wilder cams without destroying your bottom end. You can add
individual throttlebodies and get huge improvements in throttle response and
power. Nitrous oxide and/or turbo boost can be 3D mapped coordinating things
like throttle position, air/water temp, ignition timing, fuel delivery,
exhaust gas temperature, etc. Want traction or launch control? Program it
in. How about turbo anti-lag? Joo gut it, meng.

-need to change fuel/ignition maps for the long-economical cruise out to
Waterfest on Thursday, the RoadRally on Saturday afternoon, and the drag
racing/autox on Sunday? Download the new info and you're getting 35mpg all
one day and then shooting flames out your exhaust the next. The absolute
control, convenience, and flexibility of these systems is mind blowing.
--
Scott F. Williams
NJ Scirocco nut
Golf GTI 16v rallycar
Mazda 323 GTX turbo assault vehicle

Check out our rally team's website!
http://www.usrallyteam.com


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