New member intro

[tsakiris at ed8200.ped.pto.ford.com]

>> It's true a mass flow sensor measures the actual flow into the manifold, but
>> we are most likely more interested in the flow OUT of the manifold.  Both 
>> mass flow and speed density systems have advantages.  I'd be interested in 
>> people's opinions on and experiences with speed density systems.

>	This is probably a dumb question but why don't you put the sensor
>between the intake and the head?  Would the presure fluxuations from the
>vavles cuaes to many problems or do you just want to reduce the number of
>sensor imputs that the software has to deal with.
>
>Henry Sommer

Pulsations would be a difficulty.  Sensors would also be exposed to higher
temperatures, much more recirculated exhaust gas (most systems place a single
sensor upstream of this), crankcase ventilation, and greater vibrations.  
These are mass produced components, not military or medical grade parts.  Cost
is a very important issue.  As a customer, how would you feel about paying for
four or eight sensors instead of one?  According to media reports of public 
response at the North American Auto Show, people think cars cost too much 
already.

Most sensors use a small sensing element, small when compared to the size of
the flow passage.  To determine the bulk flow through the passage, 
approximations of the distribution of the flow over the entire cross-sectional
area must be made.  The more pulsations and the greater the pressure range the
harder this will most likely be.  (Note:  mass flow sensors located upstream
of the throttle, as most are, are exposed to essentially constant ambient
pressure.  Sensors in or downstream of the intake manifold will be exposed to
pressures ranging from full vacuum to ambient pressure.)

And we haven't even touched on software and electronic loads.

Tony

p.s.  (Don't think there are any dumb questions.  I'm still interested in 
       people's experiences with speed-density systems.)