<VV> RE: Re: turbo distrubutor

[John]

I haven't built the unit so I can't speak from actual experience.  But,
it uses the following pressure transducer, a Motorola MPX4250 ...  

"The Motorola MPX4250 series Manifold Absolute Pressure (MAP) sensor for
turbo boost engine control is designed to sense absolute air pressure
within the intake manifold. This measurement can be used to compute the
amount of fuel required for each cylinder. The MPX4250 series sensor
integrates onchip, bipolar op amp circuitry and thin film resistor
networks to provide a high level analog output signal and temperature
compensation. The small form factor and reliability of onchip
integration make the Motorola MAP sensor a logical and economical choice
for automotive system designers" (End Quote)

See:<
http://e-www.motorola.com/webapp/sps/site/prod_summary.jsp?code=MPX4250&nodeId=01126990368716
>

for detail.

I'm very familiar with the Megasquirt controller and it does support
turbos.  MJL, Jr. being a derivative design very likely does also.  If
you have the electronic skills give it a try.

John

> Date: Mon, 26 Apr 2004 08:59:52 -0400
> From: "Duane, Jim" <Jim.Duane@DigitalNet.com>
> To: "Jim Burkhard" <burkhard@rochester.rr.com>, "John"
>   <jdozsa@carr.org>,
>    <virtualvairs@corvair.org>
> 
> An electronic means to a mechanical end...  By the sample screen shots,
> looks like it can't handle boost conditions...
> 
> Jim Duane

SNIP>

> Yep, I am familiar with this collaboration kit, but haven't bought it
> yet since I still have a Megasquirt and a Wide Band kit to put together.
> It's a good idea and anything that gets you past the limitation of the
> stock turbo distributor should be considered.
> 
> Jim Burkhard

SNIP

> > You turbo guys need to solve the turbo distributor advance problem
> > with modern electonics.  You need "Megajolt Lite, Jr"!  MJLJ uses a
> > RPM x MAP (Manifold Pressure) table to configure the ignition advance,
> 
> > commanding a Ford EDIS module to adjust the ignition advance based on
> > the engine's current runtime condition.  You can configure the
> > distributor curve to anything you want.  Take a look at:
> >
> > <http://picasso.org/mjlj/>
> >
> > Cost less than $100 bucks if you use junk yard parts.  No Ford jokes
> > please!  Ford sparks are as good as GM sparks.
> >
> > John

SNIP

> > > Bah!  You can't "eliminate" the need for vaccum advance
> > UNLESS you are
> > > doing ALL full-throttle driving. Mechanical advance only is
> > fine for a
> > > race car, but on anything that is driven anytime part throttle
> > > (including all streeted cars), you will be underadvanced and the
> > > throttle response & fuel economy will suck.  All spark
> > ignited engines
> > > need to increase the spark advance at part throttle loads.
> > There's no
> > > way around it. If you crank up the static or centrifal advance to
> > > (ahem) "compensate" for the lack of a vacuum advance, you
> > will then be
> > > over-advanced at full load (prone to knock and/or losing
> > torque from
> > > the optimal timing).
> > >
> > > The fact that GM didn't have a V.A. on the turbo
> > distributors was only
> > > because they were trying to keep the whole deal simple and
> > having BOTH
> > > a pressure retard and vacuum advance would have made things more
> > > expensive. But one level of spark advance (reardless of
> > load!) at all
> > > engine speeds up to 4,000 rpm (or is it 4400, I forget...)
> > is no way
> > > to run an engine, though. No modern car dispenses with load-varied
> > > spark advance. Sure, it's all done electronically (no distributor),
> > > but the optimum spark advance ALWAYS varies a lot with load. No way
> > > around it whether a turbo engine or not...  To not do so means you
> > > lose part throttle torque (feels unresponsive and you have to go
> > > deeper into the throttle to make the car move) and also
> > fuel economy
> > > (on account of a drop in indicated thermal efficiency from the
> > > mistimed combustion).
> > >
> > > Jim Burkhard
> > > Air, Fuel, and that other one... Now what was it...?