Difference between 8973 and 7531

Discussion in 'PSI Superchargers Tech Questions' started by rickey, Sep 29, 2009.

  1. rickey

    rickey Member

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    are they the same? what the difference if any?

    thanks
     
    #1
    rickey, Sep 29, 2009
  2. crashly

    crashly Member

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    7531 has slew rate limiter, and data logger....


    a few differences
     
    #2
    crashly, Sep 29, 2009
  3. Outlaw68

    Outlaw68 Member

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    8973 has timing curve based on TIME..
    7531 has timing curve by rpm..
     
    #3
    Outlaw68, Sep 30, 2009
  4. jody stroud

    jody stroud ZOMBIE Top Dragster

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    The 8973 is an addition to a Mag set-up to control timing, etc. during the course of a run. A 7531 is a complete ingnition system used by nat. aspirated motors and NOS motors. I have been told by MSD that you can wire it in a MAG and use the timing and slew rate functions to control the mag, same as the 8973 but alot better. The tech's I spoke with could not answer why it was better but that it just was . Something to do with it , for some reson, being alot more resistant to mag RFI messing it up during a run. Some racers run the 8973 and have no problems others (Will Hanna, to name one ) have seen it destroy blown alcohol motors. I am going to try my 7531 with my new Fontana como late this year or early next year.
     
    #4
    jody stroud, Sep 30, 2009
  5. Mike Canter

    Mike Canter Top Dragster
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    Nitrous users of the MSD Digital 7 series have just as much problems with RFI or EMI on a crank trigger as with a 8973. Also it is basically the same same software with a few changes.
     
    #5
    Mike Canter, Sep 30, 2009
  6. jody stroud

    jody stroud ZOMBIE Top Dragster

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    I was not aware of NOS racers having problems with a digital 7, I've run them for years on my nat. aspriated motors with zero problems, LOVE it on a reg. motor.
     
    #6
    jody stroud, Sep 30, 2009
  7. rickey

    rickey Member

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    can you explain how the slew rate works
     
    #7
    rickey, Sep 30, 2009
  8. Mike Canter

    Mike Canter Top Dragster
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    In a nutshell you make the best run then you record that RPM trace and it sets boundries above it so if the rpm suddely increases above that level it will retard the ignition. It has been pretty hard to get right. Most racers end up turning it off. It is old technology and is considered to be traction control ins numerous associations.

    Jody, you only get the EMI/RFI problem in a Digital 7 in a nitrous motor if you use a crank trigger and also do not have the special shielded crank trigger cable.
     
    #8
    Mike Canter, Sep 30, 2009
  9. Outlaw68

    Outlaw68 Member

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    7531 wont retard timing on a slew.. It will however activate the RPM limiter when it runs above said slew.. But if you know how to make the 7531 work on a timing control slew.. Im listening..
     
    #9
    Outlaw68, Oct 4, 2009
  10. Mike Canter

    Mike Canter Top Dragster
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    Sorry, I believe you are correct in that it does it with an RPM limiter.
     
    #10
    Mike Canter, Oct 4, 2009
  11. rickey

    rickey Member

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    better

    is there anything out or coming out that is better than theses 2 units?
     
    #11
    rickey, Oct 6, 2009
  12. Danny Humphreys

    Danny Humphreys Member

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    #12
    Danny Humphreys, Oct 6, 2009
  13. rickey

    rickey Member

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    price

    around $900 vs $4500

    can't be that much better


    :eek:
     
    #13
    rickey, Oct 6, 2009
  14. Danny Humphreys

    Danny Humphreys Member

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    #14
    Danny Humphreys, Oct 6, 2009
  15. Flyboy68

    Flyboy68 Member

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    That thing looks awesome. Anyone have any experience w/ that traction control? I'm curious how you like it. PM me if you don't want anyone to know you're using it. ;)

    Josh
     
    #15
    Flyboy68, Oct 7, 2009

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