NHRA Legal MSD Timing Control

Discussion in 'PSI Superchargers Tech Questions' started by nitrohawk, Dec 2, 2006.

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  1. nitrohawk

    nitrohawk New Member

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    The MSD site says the TAD legal controler is either the 8971 or 8973. I thought it wasn't such a bad deal until I looked at the wiring diagram and saw that two were required for dual mags!
     
    #21
    nitrohawk, Dec 4, 2006
  2. Mike Canter

    Mike Canter Top Dragster
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    Having two 8973s or 8971s is going to cost. You would think that MSD could output a dual set of connecting wires for a dual mag application. Maybe once everyone starts using them they will do that.

    LowCountry......I will ask my inside contact at MSD about the bypass for the Launch Retard time delay. It may take a few days.
     
    #22
    Mike Canter, Dec 4, 2006
  3. T.Howell

    T.Howell Member

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    Hawk, the 8971 has the top fuel limiter in it, the 8973 does not.

    Go to this page: http://www.msdpromag.com/downloads.htm
    then go down to ProData + software.

    It is a large download if you have a slow connection but you can use this software to actually program your unit if you get one (or 2).
    The wiring isn't as bad as it looks and you won't need to use all the trigger wires in your application.
     
    #23
    T.Howell, Dec 4, 2006
  4. bryanbrown

    bryanbrown Member

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    shift signal

    Mike,
    how are you signaling the box that a shift has occured? Do you use the rpm drop function? Also, do you launch on the rev limiter? If so, what do you think about it. Does it sound like a two step, or is it smoother. Why do you use a clutch and WOT switch. We were just going to use a transbrake button on the brake handle. I was concerned about staging (lifting clutch off switch), or pedaling during the run (coming off WOT switch). Isn't there a function that will sense an rpm, and then start the time. sorry for so many questions. thanks
    bryan
     
    #24
    bryanbrown, Dec 4, 2006
  5. Mike Canter

    Mike Canter Top Dragster
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    It uses RPM drop to sense gear change. You can set the drop amount. It has to reach the set shift RPM for that gear before it will use the drop to note a shift so pedaling has really no effect on it unless while pedaling you exceed the shift point RPM.
    The MSD digital system uses a soft touch rev limiter all the limiters. It never shuts the spark down to the same cylinder twice in a row. It sounds different to a regular Two Step which uses the same cylinders over again. We launch on the rev limiter and have had no problems yet.
    You could use a transbrake button as the reset but I don't know how it would start the timer if you used that vice the RPM switch. As far as I know it only uses the blue wire trigger going to 0 Volts to start the timer. Lifting up on the clutch pedal and pushing it back down would only keep resetting the box to the ready to launch mode so you could do without the WOT switch in series. If you lifted the clutch pedal to stage while on the launch rev limiter it will release the rev limiter. We use the clutch switch and WOT switch together to prevent that and to also start other non 8973 timers which could be falsely started if you lifted the clutch pedal while staging.
     
    #25
    Mike Canter, Dec 4, 2006
  6. nitrohawk

    nitrohawk New Member

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    T. Howell,
    Thanks for the info on the download site. I do have a hi speed internet connection so will down load and play with it. Still supprised that you would need two of these units for dual 44's. Do the TFD have two units. I know a single six shooter and retard box will control the timing on both mags. Looks like it would only be a cable issue but what do I know!
    Bob Holley
     
    #26
    nitrohawk, Dec 5, 2006
  7. bryanbrown

    bryanbrown Member

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    mike
    are you dropping cylinders at the launch, since it's wide open? I can't get my mind wrapped around using both switches. I must be missing something. Why doesn't the rev limiter cut loose when you lift off the clutch to stage? are they both going to the dark blue wire? I'm sorry I keep asking questions.
    thanks
    bryan
     
    #27
    bryanbrown, Dec 5, 2006
  8. Mike Canter

    Mike Canter Top Dragster
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    Yes we are dropping cylinders at staging but not the same cylinders twice in a row. It does not load the plug and does not hydro lock the cylinder.

    I might have confused the issue here so let me re-state it. We use the side of the clutch switch that will provide 12 volts to the MSD box only via the blue wire when the clutch pedal is to the floor. This both resets the 8973 box, 8973 timer and 8973 gear to first gear, puts it into the ready to go mode and turns on the 8973 launch rev limiter (Two Step). The switch is adjusted so you have a small amount of movement in the pedal without turning the 12 volts off just for safety but not much (incase the driver sneezes). We normally do not let up on the clutch when on the rev limiter and just lighten up on the brake handle to move forward. We learned this from our nitrous days because if you let up on the clutch a little with the accelerator floored when staged it would in turn on the nitrous and release the Two Step. In your case you would not need the WOT switch because we use it to via the clutch switch (12 volts when pedal released side) and the WOT to start non MSD 8973 timers.

    Does that make better sense? I have to keep think how you guys differ.
     
    #28
    Mike Canter, Dec 5, 2006
  9. bryanbrown

    bryanbrown Member

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    I thought about putting a switch on the clutch that would have some travel, but I didn't know where to get one. any suggestions
     
    #29
    bryanbrown, Dec 5, 2006
  10. Mike Canter

    Mike Canter Top Dragster
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    Most places like Bickel or McAmis sell clutch switches with roller levers that you can mount on a slotted plate to allow adjusteent
     
    #30
    Mike Canter, Dec 5, 2006
  11. bryanbrown

    bryanbrown Member

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    thanks, that definitely seems like the way to go.
     
    #31
    bryanbrown, Dec 7, 2006
  12. Will Hanna

    Will Hanna We put the 'inside' in Top Alcohol
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    8973

    don't forget when you get ready to buy that 8973 box, ITA advertiser Robert Reehl Equipment is an authorized MSD Dealer!
     
    #32
    Will Hanna, Dec 8, 2006
  13. nitrohawk

    nitrohawk New Member

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    Thanks Will.
    I talk to Robert fairly often but did not know he was an MSD dealer.
    He is a good guy to do business with.
    Bob Holley
     
    #33
    nitrohawk, Dec 8, 2006
  14. Nitrofish4700

    Nitrofish4700 New Member

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    We have been using the 8973 on our blown alky FED and have had great success with it we leave a 3100 on the tranny-brake WO throttle a good accessory to go with it is a msd 7550 hand held programmer we can make changes very quickly in the staging lanes also if the box has a power loss it will shut the mag off if u use a 8830 capacitor it will give u a reserve power source in that event
     
    #34
    Nitrofish4700, Dec 8, 2006
  15. nitrohawk

    nitrohawk New Member

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    Have you ever looked into wheather you can use the power on/off switch to the 8973 for on off switch for the mags? I now use the power on/off switch to the six shooter/retard as an on/off switch for the motor. MSD said this was fine. On one run the battery wire broke off at about 1/2 track and the motor shut down instantly.
     
    #35
    nitrohawk, Dec 8, 2006
  16. Beal TAD519

    Beal TAD519 Member

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    Can anyone give me a physical size of the 8973? I called MSD and they couldn't tell me. Can someone measure their's and give me some approx dimensions?

    Thanks,
     
    #36
    Beal TAD519, Dec 8, 2006
  17. Mike Canter

    Mike Canter Top Dragster
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    Measuring the footprint is 8.75" x 4.75". That does not include the connectors on the end.
     
    #37
    Mike Canter, Dec 10, 2006
  18. Beal TAD519

    Beal TAD519 Member

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    Thank you.
     
    #38
    Beal TAD519, Dec 11, 2006
  19. Crew

    Crew Volunteer

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    The MSD site doesn't show anything on using the starting line limiter for NHRA. IHRA prohibits it. Does anyone know if this option can be used in NHRA TAD/TAFC?
     
    #39
    Crew, Dec 11, 2006
  20. Sportsman

    Sportsman TA/FC

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    From MSD site:
    11/29/2006
    NHRA has announced the following:
    Components In Alcohol
    For 2007, NHRA will allow all applications in Top Alcohol Dragster and Top Alcohol Funny Car to utilize a programmable ignition system. Only preset times, throttle position, engine rpm, and other internal engine data may be processed with regard to control of the ignition system. Programmable multi-point rev limiter and/or any rate-of-acceleration rpm limiter in any form is prohibited. Also allowed in Top Alcohol Dragster and Top Alcohol Funny Car is the use of electrical or electronic timers to control pneumatic fuel-system valves.
    This means the MSD PN 8973 and PN 8971 are legal for the 2007 Race Series!
    Link to the Help file in Graphview.
    Instructions: Programmable Pro Mag Controller PN 8973
    Download Podcast
     
    #40
    Last edited: Dec 12, 2006
    Sportsman, Dec 11, 2006
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