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

    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
    Based off of the Da for 6/2 and using correction 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

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

    Sledder Junior Member S197 Team Member

    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

    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

    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

    Max foot braking is 2200rpms
    Joe combs likes this.
  7. TerryZak

    TerryZak Junior Member

    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


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

    86GT351 forum member

    This man knows!
  10. Pentalab

    Pentalab forum member

    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

    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.
    Pentalab likes this.
  12. Daniel Roberson

    Daniel Roberson Member

    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

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

    Midlife Crises Senior Member

    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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