So, I have a car I'm tuning using a road dyno software. This software basically uses the gear ratio of the car, it's total weight, and the speed it moves the RPM to determine it's power output (HP and Torque) In order to use this software a flat road is needed. That works well and is very accurate compared to real dynos My area doesn't have a road that long for tuning in higher gears, But there is a very long hill with a fixed gradient of 12.8%. If the test is done on this hill, unsurprisingly, the output from the software is much lower. How can I use this information to correct the output from the software. EG: Hill of 12.8% grade reads 280hp What is the true power if the road was flat?