Is A8 transmission electronically torque limited

Discussion in 'SRT Hellcat Performance' started by jtcarlsen67, Oct 20, 2015.

  1. jtcarlsen67

    jtcarlsen67 Rookie

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    Can't seem to find a concrete answer on Internet or this forum. Does anyone know for sure if the hellcat auto transmissions are torque limited electronically? Also does anyone know the upper limits of torque tolerance for the auto? Thanks
     
  2. TIGwelder

    TIGwelder SSDD

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    I think Top Cat posted they had hit a limit. Maybe he can come in and explain what they found
     
  3. purnrg

    purnrg BANNED

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    Heard it is set at 670lbft and cuts boost back to 4-5lbs, Top Cat noticed this on a couple of his 9 second runs, they are posted somewhere here
     
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  4. gilgamesh

    gilgamesh Silver Member

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    But, they are making a HELL of a lot more than 670tq on those runs. Is that just a ballpark number and the computer regulates when it is sensing slip on the internals? Basically lets the engine go until it senses the tranny having trouble keeping up?
     
  5. eeldrethative

    eeldrethative Rookie Hellcat Supporting Vendor

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    There's engine torque management in the ECU, which can be tuned out. There's also torque reduction for the shifts in the TCM, but we seem to blow right through it with big power. ;-)
     
  6. Top Cat

    Top Cat Gold Member Hellcat Car Club Gold Supporting Member Fastest Cat/Record Holder HCC Charter Member

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    The trans is tied to a lot of different variables not only TQ, we reached the limits on the 4-5 shift when All the HP/TQ is at is max, but this may not be a trans issue as much as a whole host of things engine related, we made a few changes this week and hope to test shortly, right now we are beyond what anyone knows..
    TC
     
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  7. jtcarlsen67

    jtcarlsen67 Rookie

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    In only ask because we are tuning my charger on a mustang dyno with the Diablo trinity after doing the ati pulley. We get to WCF TQ of 668 and WCF HP 648 at 5300 rpm and then he boost drops from 13 to 9 and AFR drops from 11.7/12.0 range to the 10's and then 9'a at the same rpm. Trying to figure out if we are being limited by the electronics or are we missing something?
     
  8. Top Cat

    Top Cat Gold Member Hellcat Car Club Gold Supporting Member Fastest Cat/Record Holder HCC Charter Member

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    I PM'd you, your issue is in the tune.
     
  9. Gallitos98

    Gallitos98 Active Hellcat Member

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    When I perform the dyno in my car sometimes the Afr drops (maybe the catalyst were hot).
    .
    Traction Control was off but I belive it makes to come down the power.
    The Whp went down from 671 Whp to 550 Whp.

    Any thoughts??
     
  10. SnoCat_001

    SnoCat_001 Rookie

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    Sorry I don't have an answer on the torque limiting question but I would like to know where you found the build #s for your particular car. I just took delivery of a 2015 Charger HC on 10/20/15 and would like to know what build number and where my car sits on the uniqueness curve.
     
  11. Top Cat

    Top Cat Gold Member Hellcat Car Club Gold Supporting Member Fastest Cat/Record Holder HCC Charter Member

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    We tested my car wed evening and so far the car is now shifting from 4th to 5th under full boost and NOS, we have some tuning to work out but this is a big step in the right direction, thanks to AJ for finding some tables we needed so Josh could try a few things.
    TC
     
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  12. Garfield

    Garfield Hellcat Member

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    All hemi's have had this since the beginning all the way back to the 03 rams... There used to be a jumper wire you could install on the harness for the tcm that would disable it. There was also a cut off on tcm for the first 30sec after the vehicle was started.. A lot of people we pre staging.. Shutting off their vehicle then restarting it and then staging... In the Rams we were seeing up to .5 better eta's from this alone. Knowing Chrysler and their pcm and tcm setups.. I wouldn't be surprised to see this still work. There also used to be a turn key mod.. Where after the vehicle was running you turned the ignition back to start and held it.. (It won't try to start the pcm knows it's running and doesn't engage the starter) after 7-8sec all pcm and tcm control would shut off leaving only the basic needs for the motor to run. All electronic gauges shut off and only mechanicals ones like rpm would work. I got my old 04 ram to 176mph doing this.

    Two things from a few years back that were free mods on other hemi's. Think they are worth revisiting to see if they still work.

    (Keep in mind.. Tcm is there for a reason.. Likely the tranny isn't really build to handle full power.. So prolonged launches with tcm disabled might lead to issues later. If either of these still works.. I would recommend at very least checking your fluid constantly to see if it's burnt. There is likely going to be a lot of slippage and friction from such.. Changing fluid and keeping it fresh will help prevent damage)
     
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