Have we been doing it wrong? High rpm's bad when not needed?

[Jstpssng]

I don't keep track of regens but perhaps should start. It seems like mine does it more often than other posters suggest.. When cutting wood my tractor sits at idle a lot. Lately I've been shutting the engine off between winches but it seems like repeatedly starting it would also create more soot.

 

[Jrasband]

I started keeping my throttle over 1500 by setting the hand throttle when I first got my Kubota as I was worried about the DPF. Now I let the RPM go down to 1000 when doing loader work sometimes, as I have so much control over the movement of the tractor if you let it throttle down when desired. For instance when picking up or setting down bales and working in high range, you want to be able to go as slow as possible at that last moment. I am more concerned about riding the clutch.

 

[JCoastie]

I seem to be in the minority and have frequent regens, clearly documented in the LS forum.
For me, I have a regen with almost every 5gal fill-up, somewhere within those 5 gallons.
If I burn through that 5 gallons fast (higher RPM) I have a regen sooner, if I burn through it slower (lower PRM) I have more time between regens, but still within 5 gallons.
Yes, something is wrong, but LS does not agree, they say that's normal.

 

[RandyT]

Something to keep in mind is people with hydrostat transmissions need to operate at a higher rpm to maintain proper oil flow to the pumps.

 

[jyoutz]

I don't keep track of regens but perhaps should start. It seems like mine does it more often than other posters suggest.. When cutting wood my tractor sits at idle a lot. Lately I've been shutting the engine off between winches but it seems like repeatedly starting it would also create more soot.

When I’m running for long periods at 540 rpms, like rotary cutting, my machine regenerates about every 75 hours. But I’ve noticed when I’m puttering around doing loader work, the frequency drops to about 50 hours.

 

[Paystar]

RPM's mean nothing. What matters is keeping in-cylinder combustion temperatures high. Which means make your engine work. Keep it under a load.

 

[Hilbilly]

My tractor soot level increases whether I am idling or running at high rpms with no load but when I run at PTO speed and work the engine, the soot level decreases. I especially note the soot level drop in the winter, when I use my inverted snow blower and run uphill. I can hear the tractor working hard. I have seen the soot level drop by as much as 5% in one pass.

When I run the gravity wood chipper at PTO speed the soot level still increases. That does not work the engine enough to burn the soot.

 

[deserteagle71]

Can't speak to John Deere. But the owner's manual for my Kubota M7060 specifically warns against idling the engine too much and I have found that to be true. As long as I keep the rpms up to at least 1800 rpm it rarely goes through a regeneration cycle. If I let it idle a lot, the regeneration cycle will occur every 10 hours or even less.

 

[ning]

https://imgur.com/SV8D1zR

This graph shows soot production as a function of power and rpm. BMEP which is effectively torque is on the vertical axis and rpm on the horizontal axis. You can see there is a sweet spot of low soot right in the range where its putting out some power at a range of operating rpm. I don't know what engine its for or how much it changes for different engines but at least it's an idea of how it is for one engine.

You can tell that letting it idle with no load is going to generate many times more soot that working it.

I (sloppily) colored the graph in as I think those are isolines? so perhaps this is more intuitive for some:

 

[steve tym]

Diesels like to be worked. When I exercise my generator, I always put a load on it.