Vacuum divider ciruit and MAC11 mods

[Kurt W. Deschler]

I would appreciate any feedback about using a series of air flow
restrictors to extend the range of a the MAC11 pressure transducer. I
think the following circuit would work:

Vacuum Source >---Flow Restrictor1---T----Flow Restrictor2---< Outsize air
                                     |
                                     ^
                             Pressure Transducer

My intuition is that this circuit should behave like a resistor network
Pout = Pin*FR1/(FR1+FR2). Fluids experts?? Clearly this would make a
vacuum leak, but if the restrictors were small enough, it should be
negligible. I was thinking a FR1/FR2 ratio of 4:1 to extend the transducer
range to 2.5 bar. The higher ratio keeps the leak side is smaller, which
is good. Ay ideas on how much flow is needed for adequate response? Could
even put a check valve on the atmospheric side so that the leak is not
present under vacuum to work around high idle (split linear curve?).

Longer term, I have a cheapo 2+bar setup in mind using a vacuum divider
and the cold start valve as a 5th injector. I would line to alter the
MAC11 program to open the cold start valve, and lean out the injectors at
the same threshold so that the rest of the boost map can be calibrated
with the cold start valve open. Any feedback on altering the MAC11 boost
sampling loop would be appreciated as well.

	-Kurt
	'87 5kcstq