Chad, With an inertia chassis dyno the “sweep time” is controlled by the final gear ratio on the kart and the power out put of the motor and chassis. Simply put if you make more power or change the gear ratio the sweep time will change, just like on a segment of a straight track.
If you wanted to test longer or shorter sweep time the karts gear ratio would have to be changed until you mimicked your desired sweep time that you have predetermined to be the sweep time for your testing. That also eliminates the need to mimick arrow drag because your on track sweep time all ready includes the drag so the karts gear ratio would have to be changed from on track gears to the proper dyno test gear that makes the sweep time the same for booth types of recording.
The only other method that could be used to change the sweep time on an inertia dyno to match on track sweep time would be to change the inertia load or weight.