I doubt you will be able to get the transmission to hold 3rd gear like you want. It is a big reason why I did 2nd gear. The reason you see 3rd gear pulls being said they are the best for Dyno runs is that they are usually 1:1 so it is the strongest gear. The actual gear does not matter when it comes to hp calculations.
As for setting up the dyno to replicate a 6% grade and a 6000lb vehicle that is not really how dyno's operate. They are kind of like a reactive resistance the more power you put into them the more they resist. So you can choose how much resistance the dyno is giving you based on how much the operator uses his right foot. Often times this is how you start tuning your base fuel and ignition maps. If you ever see pictures of a dyno operator sitting in the driver's seat staring at a laptop he is literally using his right foot to manipulate the throttle to hit as many of the load cells in the map as possible to ensure the set target AFR matches the actual AFR.
So if you are wanting to do some kind of stress testing he could hold it at a given load for longer periods, but the entire point of a dyno is increasing force to match your max hp/torque.
As for setting up the dyno to replicate a 6% grade and a 6000lb vehicle that is not really how dyno's operate. They are kind of like a reactive resistance the more power you put into them the more they resist. So you can choose how much resistance the dyno is giving you based on how much the operator uses his right foot. Often times this is how you start tuning your base fuel and ignition maps. If you ever see pictures of a dyno operator sitting in the driver's seat staring at a laptop he is literally using his right foot to manipulate the throttle to hit as many of the load cells in the map as possible to ensure the set target AFR matches the actual AFR.
So if you are wanting to do some kind of stress testing he could hold it at a given load for longer periods, but the entire point of a dyno is increasing force to match your max hp/torque.
