Need help! Racepak V300SD RPM

Discussion in 'InsideTopAlcohol.com Tech Questions' started by Hthompsonjr, Jul 3, 2019.

  1. Hthompsonjr

    Hthompsonjr New Member

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    HI all....need some help. Have a racepak v300sd. Was originally a nitrous car. Came with the racepak v300sd in it. I changed it over to a blower car, 44 amp mag. Grid ignition.Tach was reading 11000 rpm when it should have only been around 3000. I called racepak and they had me change the engine rpm setting in the unit under pulses per revolution from 2 to .5. Now, it is at 6000 at an idle and when I bring it up high the tach is topping out at 19999 rpm. So the reduction in the pulses per revolution number made it worse.
    Anyone know what that setting should be at? I tried calling Racepak but they are now gone for the holiday weekend. Any help would be appreciated!
    Thanks Harold
     
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  2. Jason Green

    Jason Green Member

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    When you say tach, are you using a gauge, a racepak dadj? Hows it wire up? Is it straight to the grid?
     
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  3. Hthompsonjr

    Hthompsonjr New Member

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    I am using a RacePak UDX dash. when I first put it together it the rpm didn't work at all on the RP or the dash. I called RP and they had me run the gray tach wire from the grid to the center middle pin for the mag pickup. Then it worked. But now I have this issue.....
    Thanks for responding! Open to any ideas.
     
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  4. tc1216

    tc1216 Member

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    ok, here's my .02. assuming its a v8 with a 44 mag, you have 4 pulses per revolution.
     
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  5. Hthompsonjr

    Hthompsonjr New Member

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    Thank you! appreciate your help. Giving it a shot. Now maybe I can actually run it. :)
     
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  6. Jason Green

    Jason Green Member

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    Have you tried connecting the rpm harness from the racepak to the gray wire from the grid?
     
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  7. Mike Canter

    Mike Canter Top Dragster
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    Ok on the Racepak Engine RPM page the setup should be
    VNET ID-Engine RPM 1=x200
    Sensor-tach, 8 cyl Electronic Ignition
    Channel mode-2
    VNET Update Rate-50
    Logger Sample Rate-50
    Pulses per Revolution-4
    Odd Fire Pulse0
     
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  8. greenracing

    greenracing Member

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    Just asking as I'm starting to work on wiring on mine... Is there any disadvantage to using the Engine RPM from the Grid V-Net channels rather than wiring the tach output to the Racepak? Then program the dash to display the Grid Engine RPM? Just thinking that it would be less wiring and signals running around for the same piece of data.
     
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  9. Mike Canter

    Mike Canter Top Dragster
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    You can do it either way. Normally you don’t want more than two items getting RPM off the gray wire on the Grid because it loads it down.
     
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  10. greenracing

    greenracing Member

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    ok, thanks Mike. I was figuring on running the gray wire to the shift controller so I'll only have one item hanging off of it.
     
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