Re: Horsepower Rating

Posted by Steve - IN on January 18, 2003 at 10:21:17 from (12.222.17.160):

In Reply to: Horsepower Rating posted by Daniel T. Maxey on January 17, 2003 at 23:18:48:

Daniel,

Yes, the rating scale has changed from '49 to now, but not in the direction you're expecting. In '71 the SAE engine dyno testing method added things like air cleaners and alternators while measuring horsepower on an engine dyno so the same engine had less HP.

As G-Man said, there's also a difference in where you measure horsepower: flywheel, PTO, or rear wheels with a chassis dyno. There are also different scales: SAE, DIN, and Asian kW which give somewhat different results. There was a recent deceptive practice flap about Jaguar cars sold here using DIN ratings to make them look more powerful than an SAE rating would.

The basic relationship is RPMxTorque=HP. So as G-man noted a slow turning M engine can have the same horsepower as a faster turning modern tractor - yet produce a whole lot more torque. That's why you see 8, 10, 12, etc speed gearboxes on the newer tractors versus the 5 speed on your M. I've got that trade off back in my barn. A JD 60 row crop and JD 1020 utility - rated within a few HP of one another. The 60 turns less than 1000 rpm, the 1020 nearly 3000 rpm. Simple math says the old 60 has about 3 times the torque of the 1020. So to make yourself feel better about the whole thing - compare the torque rating of your M against the newer machines.

Steve

Follow Ups:

• Re: Re: Horsepower Rating Robert in W. Mi 13:34:49 01/18/03 (0)
• Re: Re: Horsepower Rating Ben in KY 10:42:08 01/18/03 (1)
  • Re: Re: Re: Horsepower Rating G Taylor 18:50:18 01/18/03 (0)

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