How much does it cost to turn a screw?

I notice in the specs for most newer tractors that weights and dimensions are all the same although horsepower varies.  If you have 4 tractors in a range from say 180 to 240 hp and all have the same weights and dimensions, that leads me to believe the only difference between them is a turn of the screw on the fuel injector pump.  If the higher hp ones had an intercooler and turbo and the smaller ones didn't, there would be some weight difference.

Many don't have a screw, all larger tractors sold today that I know are at least electronic injection if not common rail.  You have to reprogram the computer.  Be careful how ever because many use one set of injectors for say the bottom 2 hp ratings and another set for the top 2 hp ratings.  The do the same for the turbos, they don't nessessarly have to weight more to push more air, they just have different shape impellors/turbine sections.  Also remember, many of the brochures that you are reading are written by marketing which many times gets weight specs and such screwed up.  I can tell you for sure on the Case/IH magnums there was some major differences on the magnums above 215 hp.  Also remember the current tractors have DPF that can be royally screwed up by putting powerchips on (which are available) and cost 1500+.  If you do add chips please at least put a EGT gauge on it to monitor it.

A guy that works for cat once told me that sometimes there are absolutely no changes to anything on an engine other than ECM programming.  The reason one costs more is as performance goes up, reliability goes down.  They have to get paid for those extra warranty claims.

We have a 8970 Ford that is factory at 210 hp. with a 456cu. engine, and a friend has a 8670 with the same 456 engine and turbo and such, but it is 145 hp. The 8670 does weigh a little less to compared to the book. They sound like completely different engines though, and they actually still had a screw on the pump.