jvilleagger - 6/24/2022 20:51

Like all things there are a lot of variables and the truth is somewhere in the middle. I used to work for a major manufacturer as a product specialist and also at a different brand dealership as well.

As far as emissions go, for the most part they don’t directly reduce HP. However depending on each manufacturers approach to meet each tier there have been some consequences. For instance, with deeres EgR system, the heat buildup can cause hotter air intake temps which reduces HP if the cooler isn’t functioning to peak capacity. On Case their tier 4a steigers had the timing retarded to meet emission level which reduced HP. When they went to tier 4b, they increased DeF dosing and corrected the timing. Everyone said the Tier 4b tractors had more power than the previous generation. With AGCO, take their Mt800E tractor. The dual twin turbo V12 design had much farther for the air to travel so the boost response was slower and recovery slower than the Cat engines.

Another difference is the specific engines you are talking and where their ideal torque range is. The Cat and Cummins engines lugged better than the Deere or Iveco engines. So while the HP might be similar, the torque range and pulling power felt much different in field conditions.

And finally, with the newer tractors the computers control so much more. Especially cat/ivts, they need the correct setting to get max power before they reduce speed. These transmissions along with some power shifts will limit power when needed to prevent tearing anything up or will shift k to neutral unlike some of the older tractors mentioned earlier. Also the increased size of alternators and hydraulic pumps create parasitic loss as well as tracks that take more power to turn than wheels do.

Sorry for the long winded post but there are so many things that can and do affect power output (actual or perceived).