speed-density and TPS

[Gary Derian]

Any mass airflow system will sense the air flow needed to fill the plenum=
 in
adition to the increased air flow to the engine.  This built in accelerat=
or
pump effect is well known and useful.

Gary Derian <gderian at cybergate.net>

-----Original Message-----
From: Brad Sheridan <sheridan at vanceandhines.com>
To: diy_efi at coulomb.eng.ohio-state.edu <diy_efi at coulomb.eng.ohio-state.ed=
u>
Date: Thursday, October 30, 1997 9:10 PM
Subject: Re: speed-density and TPS



>  The use of delta-P
>across the throttle "hole" and its area will tell you the volume quite
>well -- and adding air temp will allow one to get a very good handle on
>the actual mass flow.
>
>The fact that at a given throttle opening and rpm the delta-P across the
>throttle
>is a constant value is why an alpha =96n system works.
>

  Is this at steady state? I'm just curious if the delta-P across the
throttle might change depending on for example the previous flow through
the system. For example, if you go from part throttle to WOT, won't the
airflow across it take a split second to smooth out and the path of air
flow to change from the way it had been going around the partially open
plate to the way it can go around the
plate now that its fully open? Could this make the delta -P seem differen=
t
over that brief period of time? And depending on the previous position of
the plate, couldn't you get different delta-P values as a result of the
changing path of airflow? This would seem to make sense to me as air does
have mass and therefore inertia. And if this is the case, then the delta-=
P
won't be constant for a given throttle position/rpm whenever the throttle
position is changing, right?

Please enlighten me:)

Curious,
Brad