Buying Advice Kubota New Models

[Bigpuddie]

DOCs require higher heat at all times to work properly. Unlike a gas engine, where heat is made thorough "leaning out" the engine, diesels actually use excess air to help cooling, which means you need to burn more fuel to raise heat. I'd be curious about actual fuel consumption of a similarly rated DOC and DPF engine working with the same load at rated speeds.

They do not require high heat. They are a pass through canister that involves a chemical reaction with the exhaust rather than a screen type filter. They can never plug up. Now, a DPF requires high heat or it will be in regen alot. A DPF tractor should idle as little as possible and run at 1500 plus rpm all the time. The beauty of a DOC tractor is that high rpm operation is not necessary. Now, there are hybrid versions of a DPF that Case/ NH were using for a while, which reduced regens, but ultimahwent to a DOC.

 

[TheMadOne]

They do not require high heat. They are a pass through canister that involves a chemical reaction with the exhaust. They can never plug up. Now, a DPF requires high heat or it will be in regen alot. A DPF tractor should idle as little as possible and run at 1500 plus rpm all the time. The beauty of a DOC tractor is that high rpm operation is not necessary. Now, there are hybrid versions of a DPF that Case/ NH were using for a while, which reduced regens, but ultimahwent to a DOC.

Higher heat. Not high. The catalyst material has an ideal working temp that's higher than what a non-emissions unit would have produced without tweaked fuel mapping.

 

[Bigpuddie]

Higher heat. Not high. The catalyst material has an ideal working temp that's higher than what a non-emissions unit would have produced without tweaked fuel mapping.

They may produce lesser emissions at higher heat, but it is not necessary to run them at high rpm. The DOC simply cannot plug up and requires no maintenance. You will never be put in limp mode with a DOC and it never needs cleaned or replaced .

 

[TheMadOne]

They may produce lesser emissions at higher heat, but it is not necessary to run them at high rpm. The DOC simply cannot plug up and requires no maintenance. You will never be put in limp mode with a DOC and it never needs cleaned or replaced .

The company still changed the fuel mapping at every RPM to increase burn temp to pass Tier IV. Which makes me wonder which engine is more fuel efficient. DOC vs DPF advantages in other areas are a whole separate kettle of fish.

 

[MessickFarmEqu]

DOC also runs a lot of EGR (exhaust gas recirc) that comes with an entirely different set of concerns and efficiency issues. That along with the higher required engine base heat to operate at all. There is no free lunch.

Interesting footnote, Kubota makes DOC only engines but chooses not to use them in their tractors.