7140 vs MX255

Thinking of trading tractors. Will the CIH MX255 pull equal to a good old Magnum 7140? In tractor data the MX has far greater PTO hp but nearly eaqual drawbar hp. What are your thoughts?

When comparing tractors I always like to go directly to the official Nebraska test reports for the data as this allows you to see the details behind what is published on TractorData. From the report we can see that the MX255 put out 219 hp at rated engine speed which also corresponded to the standard 1000 rpm PTO speed. This tractor's maximum power of 248 hp occurred at a lugged-down engine speed of 1650 rpm which is 350 rpm below rated speed. The 7140 produced 198 hp at rated engine speed which also gave 1000 rpm at the PTO. (This isn't the case for many tractors and the test will show two PTO power numbers, one at rated engine speed and another at the standard PTO speed of 540 or 1000 rpm.) However, it's maximum power of 209 hp occurred at 2000 rpm, only 200 rpm lower than rated speed. This indicates that the MX255 has a much stronger power bulge but if operated at normal engine speeds the two aren't as far apart as what the max power numbers would suggest.

The reporting of the drawbar power tests changed slightly between these two models so it isn't quite as easy to compare. As with the PTO tests the MX255 produced maximum power at 1650 rpm and at this engine speed it put out over 210 hp which is quite a bit higher than the 7140's maximum of 180 hp. When comparing drawbar performance it is better to look at the power instead of the pulling force since the pull is directly related to how heavy the tractor is ballasted and, obviously, what transmission gear is being used. Power isn't effected so much by this, especially at speeds above 4 or 5 mph. Folks often like to compare the maximum pulling force but it is the power that determines how much work you can do in a given amount of time.

It should have no problem keeping up or out pulling the ole 71 unless it's putting out 250hp. I wouldn't be surprised if the MX255 is putting out close to that on a dyno. There are several MX240s around my area that put out 240hp new from the factory, a neighbor still has one of them he bought new. His previous 7240/8940s would not touch it. Our MX180 2wd puts out 180hp at rated pto speed on the dyno, but it will not keep up to our 2390 or 7130 both running about 200hp and 2wd when trying to pull the same field cult or disc chisel. Boxcar Magnums are hard to beat though! Keep it and use it for a backup and buy the MX255 too Then you have the best of both worlds.

Brad

I gotta give him the benefit of the doubt here. My guess is there's some worry about the condition/longevity/reliability of the 7140, which is why he's considering trading for the MX255.

Of course you also have to take into consideration that the previous owner of the MX255 didn't trade it in because it was a perfectly good tractor either... All too often these tractors run beautifully, shift beautifully, and drive beautifully on the dealer lot, but as soon as you get them home, the wheels fall off.

Thanks guys. Actually I am thinking about keeping the 7140 and adding the 255. However I want to be sure the 255 will readily pull the same equipment at the same speed.