Dyno testing with an auto trans... questions, ideas? - NCRS Discussion Boards

Dyno testing with an auto trans... questions, ideas?

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  • Duke W.
    Beyond Control Poster
    • January 1, 1993
    • 15660

    Dyno testing with an auto trans... questions, ideas?

    Chassis dyno testing a manual is easy, and I always recommend starting pulls from 1000 revs so the full torque and power curves are revealed. (Any properly set up OE engine even with a 30-30 cam should pull without protest from 1000.)

    It gets complicated with an automatic because even if you drive it to the point where the trans shifts into top gear and then slow down to low revs, when you floor it, the transmission will downshift, so you really can't get the torque and power curves much below 3000.

    I don't have much experience playing around with automatics, but if one were do disconnect the downshift rod from the throttle linkage on an old style Powerglide or TH400, would that prevent the transmission from downshifting when you go to WOT from very low revs?

    Another method would be to do pulls with the selector level locked in Low, but then there will probably be more rear wheel torque than roller friction to contain it, and the tires will likely break loose, so that probably won't work.

    Duke
  • Mike F.
    Expired
    • April 25, 2011
    • 668

    #2
    Re: Dyno testing with an auto trans... questions, ideas?

    When I had a 91 auto, we would do the runs in 2nd gear. I forget what the exact speed was, but if you started the runs at 20-25mph in 2nd, when you nailed the accelerator it wouldn't downshift into 1st.

    IIRC, 91 auto, 3.08:1, daily driver, 230hp/340tq, best ET 13.80@100mph.

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