The reason we're seeing the advertised HP of a tractor being based on flywheel HP is because it's becoming an industry standard now, and we can thank our European brethren for this innovation. For years they've been advertising tractors this way in europe and a good majority of U.S. farmers are asking for the same thing, to quickly size tractors against one another. A little digging and you will find PTO hp, drawbar HP of any tractor you want, new or used that is rated by flywheel HP. Hence your STX(steiger frame)430(rated engine hp), much like any new deere 8r or 8rt.....8(frame)360(engine hp)R(row crop) or T(track tractor)
I wouldn't say buyer beware....that's like buying used equipment without knowing any of the history. I consider it 'doing your homework' and asking your salesman all the right questions. When you buy new or like new, it's not considered 'buyer beware' anymore.
Well my Case 7140 has mostly the same components as a 7120 and it does over 200 hp at Nebraska. So with 7140 injectors it should easy do 170. Only other thing I know of is that the final drive epicyclical reduction gears are wider in the 7140 compared with the 7120.
well this spring , the 7120 that was supposed to have 170, didnt do much better than my 5088 that supposedly dynoed at 155. this was pulling a 22ft 496 disc. shouldnt i notice 15 horse difference?
My neighbors and I both have 7120's...theirs has over 10,000 hours on it..and it's still their main planting tractor...and mine has close to 7000. I believe theirs is set at 185 PTO horsepower..but I've never dynoed mine. I pull our 22 foot 496 fairly well with it..unless, the ground is really soft and it buries itself. The difference in horsepower is very easily adjusted. If your tractor isn't putting out what you think it ought to..take it to the dealer and have it turned up. I was trying to pull our 24 foot field cultivator one day with it..and thought I needed more smoke...and did it myself. I did adjust it back down when I finished...but it didn't heat the motor up..and I could have just left it set that way.
I have a JD 7800 and I notice that some (the earlier ones) Nebraska tests state the PTO power is 145 hp. Some later tests say 158 hp. I notice that the difference is due to the revs. The rated engine speed is 2200 and if you keep it up at that speed I the maximum hp is 145 - like they say. But Maximum Power of 158 hp is at lower revs. I'm not sure if its 1800 or 1900. So they have the motor all out and load it down to 1800 or 1900 to get maximum PTO power. So that's one way I'd say that tractor hp has changed. Load it up a little and you get more power.
Tractordata.com uses the nebraska tests and summerizes it in a way that makes it faster to evaluate- to me. May be another resource in your pocket when doing your due diligence.