Telling the dyno what gear ratio you happen to be in is not going to change the measured tq. There is not even a correct way to calculate drivetrain loss accurately. We have the ability to enter the gear ratio, but this is only used to generate a tach signal on diesels, or cars that are a pain to get an accurate rpm pickup from the usual methods. I am only intimately familiar with the dyno we have, but I know it is not possible to calculate real-world hp/tq from whp by knowing the gear ratio of the transmission. It would be like saying "FWD drive cars have 10% drivetrain loss" which is not always true especially between different car manufactures. If there is in fact dyno software that will manipulate the measured tq. and correct it based on a ratio input from the operator, it would be at best a very rough estimate.
Modified by Dubmekanik at 3:05 AM 10-19-2009