Vacuum divider ciruit and MAC11 mods

[Mihnea Cotet]

Kurt, the only problem you'll have will be knocking due to too much timing 
advance for the boost levels you'll be running. IMO it would be more 
interesting to use a real 2.5 Bar transducer and have the chip reprogrammed 
for the extended range of this new pressure transducer...

HTH,

Mihnea

At 13:03 12/01/2004 -0500, Kurt W. Deschler wrote:

>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
>
>
>
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