Dyno Vs.Drag Strip Testing

The engine dyno will tell you how much POWER the ENGINE is producing. The time slip will tell you the TIME it took for THE CAR to go from point a to point b. Those are two different measurements. If you use a time slip to calculate the power being produced By THE CAR at the traps then it can be used to tell you how much power is lost between the engine and the wheels for that time duration.
Years ago (1975) my car club toured the Kieth Black facility. He had a Ford NASCAR engine on the dyno at the time. He stated that he was using the engine dynamometer to optimize THE ENGINE and that the car setup would be optimized once the engine was installed. He then had his assistant do a test run on the engine to show us the information that was obtained to help tune the engine.