Matt wrote:

Thinking about this more..  If you used an integrator, you need
to set it up so that the integration window is only during the
port-open time.
Otherwise, you might as well use the thing I was talking about
(essentially a mechanical integrator).

Okay, so maybe you need a peak-detect-hold circuit..  The way it
would work is the output from the MAP sensor would be fed to the
input of the peak-detect-hold circuit, and then to the MAP input
on the EI computer.
An output from the EI computer would reset the peak-detect-hold
circuit - preferably when the port is closed on each cycle of
operation.  This way, you get to see the full value of the
supercharging effect, and the timing of the MAP sample becomes
a moot issue..  The hold portion of the peak-detect-hold circuit
retains the sampled peak voltage until it gets reset.  How's that?

Here's an IC that looks like it might be the right idea.  I haven't
priced it..

http://www.amptek.com/ph300.html

Or maybe something like this, though you'd have to rig a switching
power supply to make it work..

http://www.chipcatalog.com/Analog/PKD01EP.htm

I suspect that we are making this problem harder than it really is.  If
we make the assumption that the shape of the pressure graph is linear
between IO and IC (which it is in Paul's graph, and likely is whenever
the manifold is "on song" as Paul puts it), then simply take one
measurement at time (Tio + Tic)/2.  That is the height of the area under
the curve between IO and IC, and the width of the area is Tic - Tio.
Easy.  The less linear the graph shape, the more error this calculation
has, but I suspect that we really only care about the full-throttle
resonant operation anyway.

Russell Kent

We are concerned about the proper mixture over a wide range
of RPMs and that curve will rarely be so simple. Some times it
could even be U shaped.

Paul Lamar