MAF and SD (was re: Re: New member intro)

[Matthew Lee Franklin]

On Mon, 9 Jan 1995 21:21:14 -0600 (CST, Jonathan R. Lusky wrote:

>GM speed density uses only MAP...

I think they use MAT also, and possibly corrections for coolant 
temperature.  At least on the QUAD-4 they did.  An ' 87 SAE paper talked 
about that in pretty inderstandable terms.  The main author was Thomson 
(spelled correctly without a "p").  I don't have the full number handy.

I have had experience with a crude speed density system (speed pressure 
actually, since we don't measure temperature).  We have applied it to two 
port fuel injected natural gas engines.  A VW 1.7 and a Hercules G1600 
industrial 163 cu in engine.  I say crude because we were free to be 
crude.  Our main focus was an adaptive, thermal efficiency maximizing 
algorithm, based on small perturbations in spark timing and manifold 
pressure (at constant fuel per cycle).  (Two recent SAE papers and one ASME 
paper cover it pretty well).  We run it with a simple fuel control and then 
constantly, synchronously, adaptively fine tune to set pulse width and 
spark timing for best efficiency.  This system can compensate for changes 
in fuel composition or system wear or other changes which are normally 
difficult to measure or correct for.  It is exciting to see how it really 
works!  Anyway, our crude speed pressure sets pulse width as a linear 
function of MAP and that is all.  It runs fine for our purposes.

By the way, I'm graduating soon with a PhD in mechanical engineering.  Does 
anybody have any openings within the next year or so?  I could use a real 
salary.

Later,
Matt