Buying Advice JD 4120, 4320, 4520, 4720, same engine, same compression, different HP. (boost?)

[charosenz]

I am looking to buy a 2014 or older JD. I have been looking at used 4000 series. What struck me as a bit odd is that it appears as though the 4120, 4320, 4520, and 4720 appear to be the same engine except the HP goes up from 43 to 60. Same bore and stroke. Same compression (+/- .5).

I can only imagine that they increase the boost on the Turbo on the higher number models in this series.

Does anyone actually know the boost pressures, and if so, a link to the data?

Thanks.

Charlie

 

[dusty3030]

I had a 4120. From what I remember there are different injectors as well on the higher hp engines in this series.

 

[LouNY]

More fuel more boost and possibly an intercooler.

 

[charosenz]

I have read the other models have larger injectors, but unless it goes with increased boost, larger injectors ( all else equal) would not increase HP. Just curious how much boost is added on those other models.......

 

[Industrial Toys]

Same with our 6200, 6300 and 6400. All the same Engine and displacement. Just different injector pumps. Kind of a ripoff if you ask me.

 

[jd110]

4120 has 7.5 psi boost, 4320 has 9 psi, 4520 has 13 and 4720 has 14.5.

 

[charosenz]

4120 has 7.5 psi boost, 4320 has 9 psi, 4520 has 13 and 4720 has 14.5.

Super,

Thanks a ton for the reply with details. I suspected as much but seeing the data is proof.

Charlie

 

[dodge man]

There may be some things to support the extra power, bigger radiator, oil cooler etc. Maybe not also.

 

[johncanfield]

I have a 2010 4720, good tractor and plenty of power. It is too small though for a 3 point MX8 shredder, it's happy with the MX6.

 

[Kyle_in_Tex]

You can get on Deere's parts system, log in, and look up stuff like injectors, pistons, etc to check for mechanical differences.