F3990

[SDT]

Picked up a 2022 copy of the Kubota Full Line Brochure today and browsed accordingly.

Noticed that the F3990, which uses the same 1505 CC turbocharged/DEF engine as the B3350/LX3310 (well aware of the differences), is rated at 36.9 gross HP vis a vis 30.8 gross HP in the 3310.

Suspect that this is a result of federale (spelling intentional) regulations but not sure. Anyone know?

Also noticed that one cannot find the F3990 on the Kubota Build It page. Assuming this is because such is not currently available but not sure. Anyone know?

 

[PaulL]

They do run a different tune often - so perhaps they're running higher revs, or have turned up the turbo a bit. The revs aren't easy to find on the web for that model for some reason, but looks like perhaps 2580 revs (which is what the front mower's running at, it'd be weird gearing to have the mower at 2580 and the engine at 2300). In the tractors it's 2400 revs, so there's a bit there.

It's also possible that tractor power ratings are subject to standards, and that for mowers you can claim whatever you want with no standards (like inboard boat motors)

 

[SDT]

They do run a different tune often - so perhaps they're running higher revs, or have turned up the turbo a bit. The revs aren't easy to find on the web for that model for some reason, but looks like perhaps 2580 revs (which is what the front mower's running at, it'd be weird gearing to have the mower at 2580 and the engine at 2300). In the tractors it's 2400 revs, so there's a bit there.

It's also possible that tractor power ratings are subject to standards, and that for mowers you can claim whatever you want with no standards (like inboard boat motors)

Could be, which is why I question regulations.

Still, 6 HP is a bunch for such a small engine.

 

[PaulL]

The difference between 2400 revs and 2580 revs could be 2-3 HP. The rest could be more turbo boost, or could be a different/more efficient driveline with less parasitic losses (I think tractors are measured with all equipment in place, so perhaps the gearbox has quite different losses), or could be simply different measurement.

The L2501 is a bad example, I know, but it's measured at 1800 revs. That same engine makes a lot more power in other applications.