1/4 mile rpm?

Mopar Racers Forum

  1. Kevin D.

    Kevin D. Well-Known Member

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    I have a 69 dart I enjoy taking to drags. Re-living my youth. Go maybe 3-4 times a year. Well on my bucket list is attend and participate in a Big Mopar event or Musclepalooza at Lebanon valley. I have only been running 1/8 mile. I have run a best of 7.15 in the 1/8. Some of these events 1/4 mile. My redlite comes on at 5800rpm. But limiter set at 6200 rpm. 727 with 4.56 gears and 28 inch tall M/Ts. What will my rpm be in the 1/4 mile is my question. Thanks Kevin.
     

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  2. twayne24365

    twayne24365 Well-Known Member

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    Whats your mph in the 1/8?
     
  3. twayne24365

    twayne24365 Well-Known Member

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    Well 7.15 should be around 95 which comes out to be about 11.20 in the 1/4 at 118ish,....depending on your converter your looking at around 6500 I would think
     
  4. JBurch

    JBurch Well-Known Member

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    It's kinda hard to say what your RPM is gonna be, since we don't know your MPH is.

    Going in the reverse direction, taking your max RPM you are chipped at now of 6200, will give you 113MPH. This is theoretical, it does not account for converter slippage, nor does it mean you will pull 6200 going out the back door.

    It would also help to know the rest of your combination.

    I would not worry too much about it, stand on it in the 1/4, you'll eather hit the chip or not. If you do, you have 3 choices, taller tire, different gears (like 4.30's, or 4.10's), or put in a different chip for more RPM. Choice is yours.
     
  5. moper

    moper FABO Gold Member FABO Gold Member

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    I'm fairly sure you'll be on the chip earlier than the 1000' mark at the Valley. I would change your gearing if you want to run the quarter, and then let your 1/8th mile fall where it may. Otherwise you'll be on the chip while the guy next to you flies by.
     
  6. 70aarcuda

    70aarcuda Master Hoader of SBM FABO Gold Member

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    put a higher chip in it...lol
     
  7. moparclown

    moparclown Well-Known Member

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    Kevin
    I do the same as in I made it up to the track 5 times this past summer, my car is a street car no cage and drag radials and a full exhaust.
    I run a mild stock stroke 360 mated to a 904 trans 4000 stall converter with a spooled 4.10 rear. I stage at about 1200 and shift at 5600 and cross the stripe at 6200.
    I run at the Valley which is 1/4 mile, a time slip from my last day at the track which happened to be Mopars at the Valley a really great event had a great time(I am car 256)
     

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  8. Kevin D.

    Kevin D. Well-Known Member

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    Thanks for all your input. Its a stroked 340. Professionally put together. Ported edelbrocks. Only weak link here is M/P cast crank. Icon pistons. Comp. cam .540/.520 solid. 4000 PTC converter. Hughes roller rockers. Timed at 34. 11.3 comp. ratio.
     
  9. stroked340

    stroked340 FABO Gold Member FABO Gold Member

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    Sounds very similar to my 416 11.02 @121 w 3.91 gear..if you can get to Lebanon valley for Mopar day always a good take:D:D
     
  10. Burntorange70

    Burntorange70 Well-Known Member

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    If you got the Mopar chassis book there is an equation in there that will help you figure it out.
     
  11. Breadburner

    Breadburner Well-Known Member

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    Put 30 inch tall tire on it....
     
  12. madmax/6

    madmax/6 Well-Known Member

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    I go tru the traps around 6500.4.56 gears 28 tires shift at 6000.11.42 @ 116mph.All motor Slant six.
     
  13. jimjimjimmy

    jimjimjimmy lobsterman FABO Gold Member

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    that's one nasty slant .
     
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    • j par

      j par Well-hung Member

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      That one light car !
       
    • crackedback

      crackedback FABO Gold Member FABO Gold Member

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      Yep...

      Banging the 6200 chip is going to kill the last 200-300 feet of track. I'd put a 6700 chip in it and run it out the back.
       
    • roccodart440

      roccodart440 Well-Known Member

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      I turn 7.40's in the1/8th and 11.70's in the quarter at 114mph. This is at Lebanon Valley.

      At 114mph your combo will spin 6200. You will go more MPH in the 1/4 than that.

      RMS has a really nice RPM calculator in his tech section.
       
    • sledger46

      sledger46 Well-Known Member

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      To estimate your MPH in the 1/4 mile add 25MPH to your 1/8 mile MPH.
       
    • roccodart440

      roccodart440 Well-Known Member

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      seems right. I pick up 22mph
       
    • D-50394

      D-50394 Well-Known Member

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      According to the Wallace Racing calculator your 1/8 converts to 11.79 @ 115 in the 1/4.
       
    • roccodart440

      roccodart440 Well-Known Member

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      That seems off to me. I go 7.48 give or take in the 1/8" and 11.74 @ 114 in the quarter. I think he'll go faster than 11.79.
       
    • bOb shingler

      bOb shingler Well-Known Member

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      well my guess is that motor will be turning 7200 with your tire size and gear, so put a 7500 chip in.
       
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      • RockinRobin

        RockinRobin Well-Known Member

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        If a taller tire will fit, that would be less stress on the drivetrain. 30 or 31" if it will fit.
        You can use your shorter tires for the 1/8th mile if you can afford an extra set of wheels.
         
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