the dynapack is probably the most inaccurate of all the dyno methods because you don't even have your wheels on...
Actually the opposite is true. Scientific testing involves minimizing variables. Without wheels you do not have the variables of:
- Inertial mass
- Tire pressure
- Camber
- Castor
- Toe
- Tire growth throughout the dyno run changing your drive ratio
Inertial dynos do not measure power. They measure acceleration and calculate the power. A subtle but important difference.
A Dynapack can pick up a single cylinder misfire with the drivetrain mass removed.
We can repeat dyno runs on a 930 HP turbo K series engine with less than 0.5 hp variation.
In the end though a dyno is a tool to determine your % torque & power changes while tuning.