B2650 actual horse power

[19thSF]

My B2650 manufactured in late 2016 has a rated 26 HP at 2500 RPM. The later models claim 24.8 HP at the same 2500 RPM. They seem to be using the exact same engine. Does anyone have an explanation for this?

They both also have the same (claimed) PTO HP.

 

[dirtydeed]

I think it was due to a different testing protocol/procedure.

 

[greenacresnorth]

they do it to sneak under the 25hp DPF cutoff, the can change nothing but the tuneup and still build the tractor to tier4 final. same as the L2501, same engine in asia makes 34hp, they detune it to 25 for the EPA mandated cutoff.

 

[SDT]

My B2650 manufactured in late 2016 has a rated 26 HP at 2500 RPM. The later models claim 24.8 HP at the same 2500 RPM. They seem to be using the exact same engine. Does anyone have an explanation for this?

They both also have the same (claimed) PTO HP.

Kubota recently rerated both the 2650 and 3350 using a different specification. This appeared to change only advertised gross engine HP, not advertised PTO HP.

No changes were made to either engine.

SDT

 

[19thSF]

Thank you for the answers. They make a lot of sense. I believe that when the tractor was made, 26 HP was just under the requirement for a particulate filter reburn system. But........................19KW (the actual requirement break point) is 25.47HP, not 26, so maybe the squeaking by was over.

I would not have thought of this. It is kind of clever. Re-test the same engine using slightly different methodology, and Ba-Bamm, the engine is only 24.8 HP!

At any rate, again, thank you for the answers. The explanation never would have occured to me, because in my thinking horse power is king, especially in advertising copy! Well, I did grow up in the muscle car era... that's my excuse, and I am sticking to it.

 

[Henro]

Kubota recently rerated both the 2650 and 3350 using a different specification. This appeared to change only advertised gross engine HP, not advertised PTO HP.

No changes were made to either engine.

SDT

I am having trouble understanding how engine horsepower could drop without a proportional drop in PTO HP...assuming that everything else stayed the same, the losses before the PTO output should remain the same...less HP in, less HP out to the PTO...

 

[SDT]

I am having trouble understanding how engine horsepower could drop without a proportional drop in PTO HP...assuming that everything else stayed the same, the losses before the PTO output should remain the same...less HP in, less HP out to the PTO...

No way to know that.

Perhaps only gross engine HP was retested.

SDT

 

[JerryMT]

My B2650 manufactured in late 2016 has a rated 26 HP at 2500 RPM. The later models claim 24.8 HP at the same 2500 RPM. They seem to be using the exact same engine. Does anyone have an explanation for this?

They both also have the same (claimed) PTO HP.

They limited the fuel to reduce the rated power at the same rpm/airflow. If the pto power stayed the same at the same condition, they didn't trim the fuel flow back at that rpm. This is easily done on a electronically controlled engine.

 

[SDT]

They limited the fuel to reduce the rated power at the same rpm/airflow. If the pto power stayed the same at the same condition, they didn't trim the fuel flow back at that rpm. This is easily done on a electronically controlled engine.

Could be but both B2650 and B3350 engines are mechanically governed and mechanically injected.

SDT

 

[North Idaho Wolfman]

One trick to changing a HP rating on an engine it to add larger crank draw down componets to a system, I.E. changing ftom a dyno to a full alternator, and AC if avalible.

 

[JerryMT]

Could be but both B2650 and B3350 engines are mechanically governed and mechanically injected.

SDT

Then they have to adjust the mechanical components in the injection pump to limit the fuel flow to a lower value at the rating point, i.e 2500 rpm. Some hydromechanical pumps actually have an adjustment screw to do this. Don't know about Kubotas. It easier to dial down. When you dial up the fuel to increase horsepower you have to worry about increased component loads and max cylinder temps.
In this age of EPA mandated emissions, I doubt that any manufacturer puts external max fuel adjustments on injector pumps.

 

[JerryMT]

One trick to changing a HP rating on an engine it to add larger crank draw down componets to a system, I.E. changing ftom a dyno to a full alternator, and AC if avalible.

There is an SAE standard method to quote rated engine horsepower and there is a corresponding international standard ( I can't remember the acronym for that but I think it maybe be JIS (Joint International Standard)). It is meant to keep all the power quotes on the same basis so you don't have apples to oranges comparisons. SO I don't think that's what happened here unless the standards changed. I think it's just a "rule beater" to escape having to do anything on a small HP tractor.