Lazy after the 1/8

Discussion in 'PSI Superchargers Tech Questions' started by Moore, Aug 29, 2010.

  1. Moore

    Moore New Member

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    Every thing seems to work reasonable well up until about 600' and then it is just lazy?
    1.0's @60' 4.27' @ 660' but only 6.80's @ 1320' - 1900# dragster, 512 Hemi, BAE fuel heads, 1471 Littlefield, 32# boost, 30 degrees advance, mallory, .017 plug gap, hat & port noz's per Spud. No data, the nut holding the wheel forgot to push the record button!
    Any input would be appreciated.
     
    #1
    Moore, Aug 29, 2010
  2. Mike Canter

    Mike Canter Top Dragster
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    You never said what transmission and rear gears you have. You are probably in high gear at that point so most likely you are 1 to 1 in the tranny and totaly on the rear gear and tire diameter. I don't know what rear gear works best in a dragster so maybe somebody can chime in and help. I do know that both in a FC and a PM if you have the wrong rear gear or the wrong diameter tire or combination of both the the motor will flatline on RPM at the shift so no RPM increase and therefore no boost increase and the car will feel real lazy. Since the motor works ok through the RPM range in first and second gear I would suspect it is something like the final drive ratio causing the problem.
     
    #2
    Mike Canter, Aug 29, 2010
  3. Moore

    Moore New Member

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    Top Dragster class - chance converter in front of a b&j three speed -, with a 3.89 rear gear & 34.5 x17 x16 tire. Yes, in high gear just prior to the 1/8
     
    #3
    Moore, Aug 29, 2010
  4. TAFC 5 81

    TAFC 5 81 Member

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    What are the trans ratios and what rpm do you leave at?
     
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    TAFC 5 81, Aug 29, 2010
  5. JP

    JP Member

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    years back we ran a tad with std roots blower and same tire size as you. i personaly wouldnt put anything numerically lower that a 4.29 with that type of engine...
     
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    JP, Aug 29, 2010
  6. jim phillips

    jim phillips ta/fc

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    3.89 gear is a hard gear to pull i know with the convertor it will leave calmer you would be better off with a lower gear and knock some timing out at the hit and ramp it back in after 60ft are one second into the run with the boost your running i think your just doggin the motor tring to pull the 3.89 gear just my thoughts
     
    #6
    jim phillips, Aug 29, 2010
  7. Alkydrag

    Alkydrag Sr. Dragster

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    That's a big chambered head and requires more lead. Also the plug gap is a little too big. It needs to be more like .012". Make sure you torque the nut next time.
     
    #7
    Alkydrag, Aug 30, 2010
  8. Moore

    Moore New Member

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    Thanks for the input guys, I had been thinking about the gear but not the plug gap. Have a 4.30 gear at the shop so will give it a try. Oh! the nut behind the wheel will get torqued! and it won't be so long between passes next time. <:)
     
    #8
    Moore, Aug 30, 2010
  9. TAFC 5 81

    TAFC 5 81 Member

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    You may have to make a minor fuel curve adjustment since the 4.30 gear won't load the engine as much.
     
    #9
    TAFC 5 81, Aug 30, 2010

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