Perhaps the dyno software is throwing out results it detects were not achieved while in 4th gear (close to 1:1).
Since downshifting can't be eliminated on an auto, maybe the curve represents the transmission characteristics as much or more as the engine output. If peak power is achieved in 3rd, and it downshifts at the same axle speed and torque as before the tune, the dyno may be ignoring (or unable) to measure the true peak ether before or after the tune. Or were they able to overcome downshifting? (edit) Even in 4th, without locking out the torque converter I think there are too many variables to get a meaningful peak output figure.
I'm curious enough to drop $50 for a power test locally. We'll see. Too bad I have no "before picture."
(edit) On second thought I think I'll skip the dyno; I don't think it's easy to get meaningful results.
This page seems to indicate dyno'ing an automatic transmission equipped car is more an art than a science:
Quote:
|
For cars equipped with automatic transmissions or special torque converters, some finessing is required.
|
