No change in 1/4 mile ET after gear change

Discussion in 'Drag Racing Tech Discussion & Timeslips' started by Fx4cobrawing, Jun 7, 2022.

  1. Joe combs

    Joe combs Member

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    DA on 6/2/2022 was 2045 at the time of your run
    DA on 9/9/2021 was 1865 at the time of your run

    Kil Kare has a DA link online
    https://airdensityonline.com/track-results/Kil-Kare_Raceway/
    Based off of the Da for 6/2 and using correction factor...it calls for a 12.91
    IF you need one, I have the converter and input shaft that are new, never installed (2 of them actually) ...I am going to be changing to a stick... I am a short drive from you. Would I have Lito set your tune for the gear...yes...
     
    Last edited: Jun 7, 2022
  2. Fx4cobrawing

    Fx4cobrawing Junior Member

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    Can we talk outside of this forum Joe?
     
  3. Sledder

    Sledder Junior Member S197 Team Member

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    For what it's worth that was exactly my experience with the gear change. No difference. 2012, 5.0, Roush TVS, (at the time) M&H 275/45/18, 93 oct tune. Went from the 3.15 to 3.73. No change in ET on the strip. I tend to think that first gear is so low in these transmissions it negates the benefit of a rear gear change. The math looks good but the results just aren't there. Lot of cars running real fast with stock gears. I started paying more attention to RPM at the stripe and ended up using 3.55 gears.
     
  4. BottleRocket

    BottleRocket Member

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    Dino is correct, it needs a higher stall to allow the engine to get higher up in the power band at launch. But now you need to start building some power into your motor. I would suggest long tubes, a high flow cat mid-pipe (I went with BBK), and a pair of stage 1 cams. I assume you already have a CAI? Lower gears are designed to allow you to take advantage of higher RPM power, which you don't have.
     
  5. Pentalab

    Pentalab forum member

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    AFAIK, the oem converter is 1500 rpm...on the 5r55s. A higher rpm stall converter, with the optimal tq ratio, would do the job. Can the brakes even hold at > 2krpm ?
     
  6. Fx4cobrawing

    Fx4cobrawing Junior Member

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    Max foot braking is 2200rpms
     
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  7. TerryZak

    TerryZak Junior Member

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    I didn't see anyone mention this, but didn't the run with the 4.10 gears have a slower reaction time by 0.5705 seconds? I'm pretty sure that if the various times were corrected for that reaction time, the 4.10 accelerations would look a little better, shouldn't they?
     
  8. JimC

    JimC Senior Member

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    Reaction time won't affect the ET - the timer doesn't start until the car breaks the beams.
     
    Last edited: Jun 9, 2022
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  9. 86GT351

    86GT351 forum member

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    This man knows!
     
  10. Pentalab

    Pentalab forum member

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    I didn't know that...till 2 years ago. ET + trap speed don't enter into the equation. It's whoever crosses the finish line 1st.
     
  11. Dino Dino Bambino

    Dino Dino Bambino I have a red car

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    True, so it pays to have a 0.01sec RT. ;)
    That said, if you're only using the strip to test your own vehicle rather than race against the other guy, you can take a snooze behind the start line if you like 'cause only the trap speed and ET will matter.
     
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  12. Daniel Roberson

    Daniel Roberson Member

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    In my experience cams absolutely suck without Long tube headers. Make sure if you do them separately then you do tubes first. The stage one cams can be a different animal to the Brenspeed rockers. Rockers in my opinion are for sound. I really didn't see a difference but on the upper end the lower end it robbed torque.
     
  13. TerryZak

    TerryZak Junior Member

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    That puts you 2 years ahead of me!! Thanks for setting straight on that one guys!
     
  14. Midlife Crises

    Midlife Crises Senior Member

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    As long as you don’t leave too soon and if running brackets you don’t run faster than your dial in.
     
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